Foramen magnum in Latin. Bones, muscles, ligaments

Spinal sections

Figure No. 7. Sections of the spine

Let's continue our tour of the entertaining anatomy of the spine. So, the spinal column is part of the axial skeleton. This structure, unique in its supporting and shock-absorbing functions, not only connects the skull, ribs, and pelvic girdle, but is also a container for the spinal cord. The human spine consists of 32-34 vertebrae. Why are such approximate figures given? Because, as you remember, we are talking about the anatomy of an “average” person. But in fact, the spine, like any other living structure, may have its own small quantitative (and qualitative) deviations, that is, its own individual structural features.

In this main part of the human axial skeleton, the cervical, thoracic, lumbar, sacral and coccygeal sections are distinguished. Let's take a closer look at these sections and the most typical number of their vertebrae.

The cervical region is the most mobile. It contains 7 vertebrae. Latin name vertebrae cervicales- cervical vertebrae ( vertebra- vertebra; cervix- neck). In medical documents, the vertebrae of this department are marked with the Latin letter “C” - an abbreviation for the word cervicales, and the index assigned to the letter, for example C1, C2, C3, etc., means the number of the vertebra - the first cervical vertebra (C1), the second cervical vertebra (C2), etc.

These vertebrae bear less load compared to the underlying parts of the spinal column, which is why they look more “miniature”. Special attention deserve the first two cervical vertebrae, which are significantly different from the others (they are also called atypical vertebrae). Although they are small in size, they are the most responsible workers who are responsible for the movable joint with the skull. Almost like people who are close to the very top of government and are responsible for... Well, let's not talk about that.

Therefore, the I and II cervical vertebrae have not only a special shape, differing in their structure from other vertebrae, but also personal names: atlas and epistropheus.

Magnetic resonance imaging (MPT) No. 1 shows the cervical spine, in a relatively normal state.

The cervical spine should have a normally expressed physiological lordosis, there should be no hypolordosis or hyperlordosis, as well as kyphotic deformities.

Spinal cord width: sagittal > 6-7 mm

1. Sagittal size of the spinal canal at the level:
C1 ≥ 21 mm
C2 ≥ 20 mm
C3 ≥ 17 mm
C4-C5=14 mm

2. Height of intervertebral spaces:
C2< С3 < С4 < С5 < С6 ≥ С7

3. Width of the spinal canal: transverse diameter at the level of the pedicles: > 20-21 mm

Figure No. 8. The first cervical vertebra is the atlas. View from above

1 - vertebral foramen;
2 - posterior tubercle;
3 - rear arch;
4 - groove of the vertebral artery;
5 - opening of the transverse process;
6 - superior articular fossa;
7 - transverse process;
8 - lateral mass;
9 - tooth fossa;
10 - anterior tubercle;
11 - front arc.

Everyone probably heard the name Atlas in childhood from the cycle of ancient legends about the gods of Olympus. True, the legends about the latter remind me more of what the Roman poet Horace spoke about long ago: "Decipimur specie recti", which means “We are deceived by the appearance of right.” So, according to ancient Greek mythology, there was a titan Atlas (brother of Prometheus), who, as punishment for participating in the struggle of the titans against the Olympian gods, held the vault of heaven on his shoulders by order of Zeus. In honor of Atlas (Greek) atlas) and the first cervical vertebra was named. It is curious that this vertebra is devoid of spinous and articular processes, and does not even have a body or notches. It consists of two arches connected to each other by lateral bone thickenings. Everything is as it happens with people in the vertical of power, they say, among the blind and crooked there is a king. With its superior articular fossae, the atlas is attached to the condyles (bone protrusions that form part of the articulation) of the occipital bone. The latter, so to speak, limit the degree of freedom (mobility) of the atlas, so that this vertebra knows its place and does not go beyond what is permitted.

Figure No. 9. The second cervical vertebra is epistrophy (axial - axis). Rear and top view

1 - tooth of the axial vertebra;
2 - posterior articular surface;
3 - upper articular surface;
4 - vertebral body;
5 - transverse process;
6 - opening of the transverse process;
7 - lower articular process;
8 - spinous process;
9 - vertebral arch

The second cervical vertebra is epistropheus. That's what Andreas Vesalius called him - the doctor, the founder scientific anatomy who lived during the Renaissance. Greek word epistrepho means “turning, turning.” The Latin name for the second cervical vertebra is axis(axis), that is, axial. This vertebra is no less important than the Atlas, if we speak humorously, then it is also that “cunning goose”. It has a bony outgrowth - a tooth-like process (called the odontoid process), around which the atlas rotates along with the skull articulated with it. If we draw parallels with human life, then the second cervical vertebra is similar to those people who stay in power by compromising their superiors. It’s not for nothing that people say, “this man has a grudge against his superiors.” This is how he is, epistropheus, small, inconspicuous, but holding his entire head. However, no matter what these vertebrae are called, both of them constitute a unique mechanism, thanks to which a person can make various movements with his head, make the same turns, bends, including hitting his forehead, when he submits his petition to the authorities.

Figure No. 10. Typical cervical vertebra (C3-C7).
View from above
1 - vertebral foramen;
2 - vertebral arch;
3 - spinous process;
4 - superior articular process;
5 - lower articular process;
6 - transverse process;
7 - posterior tubercle of the transverse process;
8 - anterior tubercle;
9 - vertebral body;
10 - transverse hole

In general, the cervical region is a “special department” of vertebral employees, who are also responsible for the safety of the head. Thanks to its unique design and operation, the cervical region provides the opportunity for the head to monitor and keep under control (visual, of course) a fairly broad part of the spatial horizon with the least mobility of the “working” organism as a whole. In addition, the transverse processes of all cervical vertebrae have special openings that are absent in other vertebrae. These openings together, in the natural position of the cervical vertebrae, form a bone canal through which the vertebral artery passes, supplying blood to the brain.

Photo No. 1. Model of the human cervical spine, which clearly shows how the vertebral artery passes through the holes in the transverse processes, thus forming a bone canal for the vertebral artery.

Available in cervical spine the spine and its “operators” - the articular processes that take part in the formation of the facet joints. And since the articular surfaces on these processes are located closer to the horizontal plane, in total this significantly expands the capabilities of the cervical spine, provides more effective mobility of the head, and allows one to achieve a greater angle of torsion. However, the latter has become a vulnerable spot for the cervical spine, given the low strength of the cervical vertebrae, their weight and degree of mobility. As they say, even the “special department” has its own “Achilles heel”.

You can find out exactly where the limits of your “special department” end by looking at the seventh cervical vertebra. The fact is that the length of the spinous processes (by the way, their ends are bifurcated, except for the VII) increases from the II to the VII vertebra. The spinous process of the seventh cervical vertebra is the longest and is also thickened at the end. It is a very noticeable anatomical landmark: when tilting the head back surface neck, the tip of the most prominent spinous process can be clearly felt. By the way, this vertebra is called in Latin vertebra prominens- protruding vertebra. This is the legendary “seven”, thanks to which you can count your vertebrae with diagnostic accuracy.

The thoracic spine consists of 12 vertebrae. Latin name vertebrae thoracicae- thoracic vertebrae. Latin word thorax- chest - derived from the Greek word thoraks- breast. In medical documents, the vertebrae of the thoracic region are designated as “Th” or “T”. The height of these vertebral bodies gradually increases from the I to the XII vertebrae. The spinous processes overlap each other in a tiled manner, covering the arches of the underlying vertebrae.

MRI No. 2 shows the thoracic region is in a “normal” state.

The thoracic region should have a normal degree of kyphosis (the Stagnara kyphosis angle is formed by a line parallel to the endplates T3 and T11 = 25°).

The spinal canal at the thoracic level has a rounded shape, which makes the epidural space narrow along almost the entire circumference of the dural sac (0.2-0.4 cm), and in the area between T6 and T9 it is narrowest.

Sagittal size: T1-T11 = 13-14 mm, T12 = 15 mm.
Transverse diameter: > 20-21 mm.
The height of the intervertebral discs: the smallest at the level of T1, at the level of T6-T11 approximately 4-5 mm, the greatest at the level of T11-T12.

Figure No. 11. Thoracic vertebra. View from above
1 - vertebral arch;
2 - spinous process;
3 - transverse process;
4 - costal fossa of the transverse process;
5 - vertebral foramen;
6 - superior articular process;
7 - upper costal fossa;
8 - vertebral body

Also a characteristic feature for most thoracic vertebrae is the presence on the lateral surfaces of the bodies of the upper and lower costal fossae for articulation with the heads of the ribs, as well as the presence of a costal fossa on the transverse processes for connection with the tubercle of the rib. Due to the specifics of its design and the small height of the intervertebral discs, this section is certainly not as mobile as the cervical spine. However, it is intended for other purposes. The thoracic vertebrae, together with the thoracic ribs and sternum, form the bone base of the upper body - the rib cage, which is the support for shoulder girdle, a receptacle for vital organs. It allows you to use the intercostal muscles during breathing movements. The connection of the thoracic vertebrae with the ribs gives this part of the spine greater rigidity thanks to the rib frame chest. So these vertebrae can be figuratively compared to people who work harmoniously and effectively in one large team, clearly performing their functions and responsibilities.

MRI No. 3 shows the lumbar spine. (In this “control” image, residual phenomena of the degenerative-dystrophic process are observed in the L5-S1 segment after the removal of a sequestered intervertebral disc herniation using vertebrorevitology.)

In the lumbar region, the shape of the spinal canal created by the vertebral body and arches is variable, but more often it is pentagonal. Normally, the spinal canal in the lumbosacral region is narrowed in anteroposterior diameter at the level of the L3 and L4 vertebrae. Its diameter increases caudally, and the cross-section of the canal takes on a shape close to triangular at the level of L5-S1. In women, the canal tends to widen in the lower sacral region. The sagittal diameter decreases significantly from L1 to L3, remains almost unchanged from L3 to L4, and increases from L4 to L5.

Normally, the anteroposterior diameter of the spinal canal is on average 21 mm (15-25 mm).

There is a simple and convenient formula for determining the width of the spinal canal:

normal sagittal size of at least 15 mm;
11-15 mm - relative stenosis;
less than 10 mm - absolute stenosis. A decrease in this ratio indicates a narrowing of the channel.

The height of the lumbar intervertebral discs is 8-12 mm, increasing from L1 to L4-L5, usually decreasing at the level of L4-S1.

Lumbar The spine consists of the 5 largest vertebrae, which have massive, bean-shaped vertebral bodies and strong processes. The height and width of the vertebral bodies gradually increase from the first to the fifth vertebra. Latin name vertebrae lumbales- lumbar vertebrae, lat. lumbalis- lower back. Accordingly, they are designated: the first lumbar vertebra is L1, the second lumbar vertebra is L2, and so on. The mobile lumbar spine connects the sedentary thoracic spine with the stationary sacrum. These are real “hard workers” who not only experience significant pressure from the upper body, but also throughout life are subject to serious additional stress, which was partially discussed in the previous chapter.

Figure No. 12. Lumbar vertebra. View from above
1 - vertebral foramen;
2 - spinous process;
3 - vertebral arch;
4 - lower articular process;
5 - superior articular process;
6 - mastoid process;
7 - transverse process;
8 - pedicle of the vertebral arch;
9 - vertebral body.

The lumbar vertebrae can only be figuratively compared to heavy-duty peasants. In the old days in Rus' (in the 15th century) there were men who worked from dawn to dusk, and even paid a full tax. Tax in the old days meant various taxes, more precisely state taxes, as well as the performance of state duties. The state taxed the hard-working peasant from all sides. In addition, he had to pull this tax not only for himself, but also for his family, at the rate of two souls per tax. Just a real lumbar vertebra with its loads. So, even according to ancient laws, this peasant remained taxable from marriage until he was 60 years old - “as long as a man, by his age and health, was considered taxable.” And after that it either moved to “half-tax”, or “quarter-tax”, or was completely shifted. A straightforward truth regarding the lumbar vertebrae and the spine as a whole in a careless owner! While the spine is young, radiant in health and working tirelessly, the owner mercilessly exploits it. And as degenerative-dystrophic processes began to develop in the spine, osteochondrosis began to develop, and so it began to work at half strength, and then you look at a quarter of its strength. Then it wears out completely. And the most interesting thing is that it is the lumbar region that most often wears out. This is the life of the spine of the owner, who spent his health wastefully and carelessly: as they used to say in the old days, “you had to get married at eighteen in order to pay taxes.”

Figure No. 13. Sacrum and coccyx. Front view.

Sacrum:
1 - base of the sacrum;
2 - superior articular process;
3 - lateral part;
4 - anterior sacral foramina;
5 - transverse lines;
6 - apex of the sacrum;
7 - sacral vertebrae.

Coccyx:
8 - coccygeal vertebrae;
9 - lateral processes (rudiments of transverse processes);
10 - coccygeal horns (rudiments of the upper articular processes).

The sacral spine also consists of 5 vertebrae fused into one bone. Anatomical name in Latin: os sacrum- sacrum bone, vertebrae sacrales- sacral vertebrae, which are designated S1, S2, etc., respectively. It is curious that the word sacrum used in Latin to mean mystery (Bullshit. The word “sacer” means “sacred”. It is used because this particular bone was used in sacrifices. And they used it because, due to its structure, it is difficult to gnaw. All other bones were safely cleaned by the priests http://www. etymonline.com/index.php?term=sacrum - H.B.) . This bone fully deserves such a name, given its structure, functions and heavy loads which it can withstand due to the vertical position of the body. It is interesting that in children and adolescents, the sacral vertebrae are located separately; only by the age of 17-25 do they tightly fuse together with the formation of a kind of monolith - a large triangular structure. This wedge-shaped structure, with the base facing upward and the apex facing downwards, is called the sacrum. The base of the sacrum (SI) has superior articular processes that articulate with the inferior articular processes of the fifth lumbar vertebra (LV). The base also has a protrusion directed forward - a cape. From the apex, the sacrum connects to the first coccygeal vertebra (CO1).

In general, it should be noted that the relief of the sacrum is very interesting and in many ways mysterious. Its anterior surface is concave, has transverse lines (places of fusion of vertebral bodies), four pairs of pelvic sacral foramina through which the spinal nerves exit. The back surface is convex. It has, respectively, four pairs of dorsal sacral foramina and five longitudinal ridges formed by the fusion of the spinous, articular, and transverse processes of the sacral vertebrae. On the lateral parts of the sacrum there are so-called articular ear-shaped surfaces, designed for articulation with the pelvic bones. Posterior to these articular surfaces is the sacral tuberosity, to which the ligaments are attached.

The sacral canal, which is a continuation of the spinal canal, runs inside the sacrum. In the lower part it ends with the sacral fissure, on each side of which there is a sacral horn (a rudiment of the articular process). The sacral canal contains the terminal filament of the spinal cord, the roots of the lumbar and sacral spinal nerves, that is, nerve trunks that are very important for the body, which provide innervation to the pelvic organs and lower extremities. In men, the sacrum is longer, narrower and steeply curved towards the pelvic cavity. But in women, the sacrum bone is flat, short and wide. This anatomical structure of the female sacrum helps to form a smooth inner surface of the female pelvis, necessary for the safe passage of the fetus during childbirth.

With its characteristics, structural features, and functions, the sacrum in a figurative comparison resembles the most ancient institution of human society: a collection of close people united through the sacrament into a monolithic, strong family - a unit of society, a pillar of statehood. In general, such people who are close to each other, who perform not only a reproductive function and are connected by a common life, but are also united by a common responsibility, mutual assistance, coherence in their life and relationships.

The last, smallest part of the spine is the coccyx. If we approach this issue with humor, then we can figuratively say about it this way: in the family, as they say, ... not without a rudiment. The coccyx is a real rudiment (from the Latin rudimentum- rudiment, fundamental principle) of the caudal skeleton of animals. The anatomical name of the coccyx in Latin sounds like os coccygis- coccyx bone, vertebrae coccygeae- coccygeal vertebrae. In Latin "coccyx" is interpreted as the word “cuckoo” (this designation comes from the ancient Greek language), and in principle the bone was named this way due to its resemblance to the beak of a cuckoo.

Figure No. 14. Sacrum and coccyx. Back view.

Sacrum:
1 - superior articular process;
2 - sacral canal (superior opening);
3- sacral tuberosity;
4 - ear-shaped surface;
5 - lateral sacral ridge;
6 - medial sacral ridge;
7 - median sacral ridge;
8 - dorsal (posterior) sacral foramina;
9 - sacral horn;
10 - sacral fissure (lower opening of the sacral canal).

Coccyx:
11 - coccygeal vertebrae;
12 - lateral outgrowths;
13 - coccygeal horns.

The coccyx consists of 3-5 rudimentary vertebrae fused into one bone. They are designated as CO1, O2, and so on. It is curious that in the early stages of development the human embryo has a tail process, which sometimes remains after birth. However, this is not a problem for medicine: the tail can be easily removed without consequences for the body. In an adult, the coccyx is a single, sedentary structure, which is shaped like a pyramid, with its base pointing upward and its apex pointing downward and forward. Unusual view has the first coccygeal vertebra. Its small body articulates with the sacrum and has lateral processes (rudiments of transverse processes). And on the back surface of the body there are coccygeal horns (rudiments of the upper articular processes), which are directed upward to the horns of the sacrum and are connected to them through ligaments. The remaining coccygeal vertebrae are small and have a rounded shape. There are many nerve endings in the surrounding tissues of the coccyx. The muscles and fascia of the perineum are attached to the coccyx. In women, the coccyx is more mobile; during childbirth, the dorsal deviation of the coccyx ensures the expansion of the birth canal. So this rudiment is not as useless as it seems at first glance.

Thus, we briefly examined the sections of the spinal column - this amazing structure, which is optimally adapted for the vertical position of the body, works clearly and harmoniously. But this is, so to speak, a review as a whole. Now I would like to draw your attention to interesting details from the same area of ​​osteology (the study of bones), regarding important elements musculoskeletal system. The human spine is a segmental organ (the word “segment” comes from the Latin word segmentum- "line segment"). It consists of individual vertebrae, intervertebral discs located between them, as well as ligaments and joints.

The skeleton of the free upper limb (skeleton membri superioris liberi) consists of the humerus, two bones of the forearm and bones of the hand.

Brachial bone

Humerus, humerus, is a long lever of movement and develops like a typical long tubular bone. According to this function and development, it consists of a diaphysis, metaphyses, epiphyses and apophyses.

The upper end is equipped with a spherical articular head, caput humeri(proximal epiphysis), which articulates with the glenoid cavity of the scapula. The head is separated from the rest of the bone by a narrow groove called anatomical neck, collum anatomicum.

Immediately behind the anatomical neck there are two muscular tubercles (apophyses), of which larger, tuberculum majus, lies laterally, and the other, smaller, tuberculum minus, a little in front of him. From the tubercles downwards there are bone ridges (for muscle attachment): from the greater tubercle - crista tuberculi majoris, and from small - crista tuberculi minoris.

Between both tubercles and ridges there passes groove, sulcus intertubercularis, which houses the tendon of the long head of the biceps muscle.

The part of the humerus lying immediately below both tubercles at the border with the diaphysis is called surgical neck - collum chirurgicum(the site of the most common shoulder fractures). The body of the humerus in its upper part has a cylindrical outline, while at the bottom it is clearly triangular. Almost in the middle of the bone body, on its lateral surface there is a tuberosity to which it is attached deltoid, tuberositas deltoidea.

Behind it, along the posterior surface of the bone body from the medial side to the lateral side, a flat plane runs in the form of a gentle spiral furrow radial nerve sulcus nervi radialis, seu sulcus spiralis.

Widened and slightly anteriorly curved lower end of the humerus, condylus humeri, ends on the sides with rough protrusions - medial and lateral epicondyles and, epicondylus medialis et lateralis, lying on the continuation of the medial and lateral edges of the bone and serving for the attachment of muscles and ligaments (apophyses). The medial epicondyle is more pronounced than the lateral one, and on its posterior side it has groove of the ulnar nerve, sulcus n. ulnaris.

An articular surface is placed between the epicondyles for articulation with the bones of the forearm (disgal epiphysis). It is divided into two parts: medially lies the so-called block, trochlea, having the form of a transversely located roller with a notch in the middle; it serves for articulation with the ulna bone and is covered by it tenderloin, incisura trochlearis; above the block, both in front and behind, is located along the hole: in front coronoid fossa, fossa coronoidea, back hole olecranon, fossa olecrani.

These pits are so deep that the bony partition separating them is often thinned to the point of being translucent, and sometimes even perforated. Lateral to the block, the articular surface is placed in the form of a segment of a ball, the head of the condyle humerus, capitulum humeri, serving for articulation with the radius. Front over capitulum there is a small radial fossa, fossa radialis.

Ossification. At the time of birth, the proximal epiphysis of the shoulder still consists of cartilaginous tissue, so the head of the humerus is almost not visible on an x-ray of the shoulder joint of a newborn.

Subsequently, the sequential appearance of three points is observed: 1) in the medial part of the head of the humerus (0 - 1 year) (this bone core can also be present in a newborn); 2) in the greater tubercle and lateral part of the head (2 - 3 years); 3) in tuberculum minus (3 - 4 years). These nuclei merge into a single head of the humerus (caput humeri) at the age of 4-6 years, and synostosis of the entire proximal epiphysis with the diaphysis occurs only at the 20-23rd year of life.

Therefore, on radiographs of the shoulder joint belonging to children and young people, according to the indicated ages, clearings are noted at the site of the cartilage separating the parts of the proximal end of the humerus that have not yet fused from each other. These clearings representing normal signs age-related changes, should not be confused with cracks or fractures of the humerus. For ossification of the distal end of the humerus, see the description of ossification of the bones of the forearm.

Video of normal anatomy of the humerus

BONES OF THE AXIAL SKELETON - OSSA SKELETI AXIALIS

The axial skeleton, skeleton axiale, is represented by the bones of the skull, spinal column and chest. The last two sections make up the bones of the body.

BONES OF THE TORSO

The bones of the body, ossa trunci, combine the spinal column, columna vertebralis, and the bones of the chest, ossa thoracis

SPINAL COLUMN

In the spinal column, there are cervical vertebrae, vertebrae cervicales (7), thoracic vertebrae, vertebrae thoracicae (12), lumbar vertebrae, vertebrae lumbales (5), sacrum, os sacrum (5), and coccyx, os coccygis (4 or 5 vertebrae) .

The spinal column of an adult forms four curves in the sagittal plane, curvaturae: cervical, thoracic, lumbar (abdominal) and sacral (pelvic). In this case, the cervical and lumbar curves are convexly facing anteriorly (lordosis), and the thoracic and pelvic curves are convexly facing backwards (kyphosis).

All vertebrae are divided into two groups: the so-called true and false vertebrae. The first group includes the cervical, thoracic and lumbar vertebrae, the second group includes the sacral vertebrae, fused into the sacrum, and the coccygeal vertebrae, fused into the coccyx.

A vertebra, vertebra (Fig. 8), has a body, an arch and processes. The vertebral body, corpus vertebrae (vertebralis), is the anterior thickened part of the vertebra. From above and below it is limited by surfaces facing, respectively, the above and underlying vertebrae, in front and on the sides by a somewhat concave surface, and behind by a flattened surface.

On the vertebral body, especially on its posterior surface, there are many nutrient openings, ramina nutricia, - traces of the passage of blood vessels and nerves into the bone substance. The vertebral bodies are connected to each other by intervertebral discs (cartilage) and form a very flexible column, the spinal column, columna vertebralis (see Fig. 7).

The vertebral arch, arcus vertebrae (vertebralis), limits the vertebral foramen, foramen vertebrale, from behind and on the sides; located one above the other, the holes form the spinal canal, canalis vertebralis, in which the spinal cord lies. From the posterolateral edges of the vertebral body, the arch begins as a narrowed segment - this is the pedicle of the vertebral arch, pediculus arcus vertebrae (vertebralis), passing into the plate of the vertebral arch, lamina arcus vertebrae (vertebralis). On the upper and lower surfaces of the leg there is an upper vertebral notch, incisura vertebralis superior, and a lower vertebral notch, incisura vertebralis inferior. The anterior notch of one vertebra, adjacent to the inferior notch of the upper vertebra, forms an intervertebral foramen, foramen intervertebrale, for the passage of the spinal nerve and blood vessels.

The vertebral processes, processus vertebrae, number seven, protrude on the vertebral arch. One of them, unpaired, is directed from the middle of the arch posteriorly - this is the spinous process, processus spinosus. The remaining processes are paired. One pair - the upper articular processes, processus articulares superiores, is located on the side of the upper surface of the arch, the other pair - the lower articular processes, processus articulares inferiores, protrudes from the side of the lower surface of the arch and the third pair - transverse processes, processus transversi, extends from the side surfaces arcs.

The articular processes have articular surfaces, facies articulares. With these surfaces, each overlying vertebra articulates with the underlying one.

Fig.7. Vertebral column, columna vertebralis. A – right view; B – front view; B – rear view.

Fig.8. Eighth thoracic vertebra, vertebra thoracica; view from above.

Cervical vertebrae

The cervical vertebrae, ve rtebrae cervicales (Fig. 9 - 20), number 7 (C1-C7), with the exception of the first two, are characterized by small low bodies, gradually expanding towards the last, 7th, vertebra. The upper surface of the body is slightly concave from right to left, and the lower surface is concave from front to back. On the upper surface of the bodies of 3 - 6 cervical vertebrae, the lateral edges rise noticeably, forming a body hook, uncus corporis (see Fig. 14, 15).

The vertebral foramen, foramen vertebrale, is wide, close to triangular in shape.

The articular processes, processu s articulares, are relatively short, stand obliquely, their articular surfaces are flat or slightly convex.

The spinous processes, processu s spi nosi, from 2 to 7 vertebrae gradually increase in length. Up to the 6th vertebra inclusive, they are split at the ends and have a slight downward slope.

The transverse processes, processus tran sversi, are short and directed to the sides. Along the upper surface of each process runs a deep groove of the spinal nerve, sulcus nervi spinal is (see Fig. 15), a trace of the attachment of the cervical nerve. It separates the anterior and posterior tubercles, tuberculum anterius et tuberculum posterius, located at the end of the transverse process.

On the 6th cervical vertebra, the anterior tubercle is especially developed. In front and close to it passes the common carotid artery, a. Carotis communis, which is pressed against this tubercle during bleeding; hence the tubercle received the name carotid, tuberculum caro ticu m (see Fig. 15).

In the cervical vertebrae, the transverse process is formed by two processes. The anterior one is a rudiment of a rib, the posterior one is the actual transverse process. Both processes together limit the opening of the transverse process, foramen processu s tran sv ersi, through which the vertebral artery, vein and the accompanying nerve sympathetic plexus pass, in connection with which this opening is also called the vertebral arterial (foramen vertebraarteriale).

C1 - atlas, atl as, C2 - axial vertebra, axis, and C7 - protruding vertebra, ve rt ebra prom inens, differ from the general type of cervical vertebrae.

The first (1) cervical vertebra, the atlas, atlas (see Fig. 9. 10. 13), does not have a body and a spinous process, but is a ring formed from two arches - anterior and posterior, arcus anterior et arcus posterior, connected between themselves two more developed parts - lateral masses, massae laterales. Each of them has an oval concave upper articular surface, facies articularis superior, on top, a place of articulation with the occipital bone, and on the bottom, an almost flat lower articular surface, facies articularis inferior, articulating with the 2nd cervical vertebra.

Fig.9. First cervical vertebra, atlas, atlas; view from above

Fig. 10. First cervical vertebra, atlas, atlas; bottom view

The anterior arch, arcus anteri or, has on its front surface an anterior tubercle, tuberculum an teriu s, on the back - a small articular platform - the fossa of the tooth, fovea dentis, articulating with the tooth of the 2nd cervical vertebra.

The 3rd arch, arcus posterior, has a posterior tubercle, tuberculum posteri us, in place of the spinous process. On the upper surface of the posterior arch there is a groove of the vertebral artery, sulcu s arteri ae vertebralis, which sometimes turns into a canal.

The second (2) cervical vertebra, or axial vertebra, ahis (see Fig. 11 - 13), has a tooth, den s, directed upward from the vertebral body, which ends in an apex, arex. The atlas along with the skull rotates around this tooth, as if around an axis.

Fig. 11. Second cervical, axial, vertebra, axis; front view

Fig. 12. Second cervical, axial, vertebra, axis; left view

Fig. 13. First and second cervical vertebrae; rear and right view

Fig. 16. Fourth cervical vertebra cervicalis; bottom view

On the front surface of the tooth there is an anterior articular surface, facies art i c u laris a n ter i or, with which the atlas tooth fossa articulates, on the posterior surface - the posterior articular surface, facies artic u laris po st er i or, to which the transverse ligament of the atlas is adjacent, lig. tra n svers u m atla n tis. The transverse processes lack the anterior and posterior tubercles and the groove of the spinal nerve.

Fig. 14. Sixth cervical vertebra, vertebra cervicalis; front view

Fig. 15. Sixth cervical vertebra, vertebra cervicalis; view from above

Fig. 17. Sixth cervical vertebra, protruding; vertebra cervicalis; right view

Fig. 18. Seventh cervical vertebra, vertebra prominens; right view

The seventh cervical vertebra, or protruding vertebra, vertebra prominens (C7)
(see Fig. 18), is distinguished by a long and unbifurcated spinous process, which is easily palpable through the skin; in connection with this, the vertebra was called protruding. In addition, it has long transverse processes; its transverse holes are very small, sometimes they may be absent.
On the lower edge of the lateral surface of the body there is often a facet, or costal fossa, fovea costalis, a trace of articulation with the head of the 1st rib.

Fig. 19. Cervical part of the spinal column; front view (x-ray)

1 - body of the 5th cervical vertebra;
2 - articular process;
3 - spinous process;

Fig.20. Cervical part of the spinal column; lateral view (x-ray)

1 - 1st cervical vertebra; 2-2nd cervical vertebra;
3 - transverse process; 4- spinous process;
5 - articular process; 6- vertebral body;

Thoracic vertebrae

Thoracic vertebrae, vertebrae thoracicae (Fig. 21-23; see Fig. 7, 8), number 12 (Th1-Th12), significantly higher and thicker than the cervical ones; the size of their bodies gradually increases towards the lumbar vertebrae.

Fig. 21 Eighth thoracic vertebra, vertebra thoracica; right view

Fig.22. Twelfth thoracic vertebra, vertebra thoracica; right view

Fig.23. Thoracic part of the spinal column;
front view (x-ray).

1 – 1st rib; 2 – costal fossa;

3 – spinous process; 4 – transverse
shoot; 5 – body of the 1st thoracic vertebra;

On the posterolateral surface of the bodies there are two facets: the upper costal fossa, fovea costalis superior, and the lower costal fossa, fovea costalis inferior. The lower costal fossa of one vertebra forms with the upper costal fossa of the underlying vertebra a complete articular fossa - the place of articulation with the head of the rib.

The exception is the body of the 1st thoracic vertebra, which has a complete costal fossa on top, articulating with the head of the 1st rib, and below - a semi-fossa, articulating with the head of the 2nd rib. On the 10th vertebra there is one semi-fossa, at the upper edge of the body; the bodies of the 11th and 12th vertebrae have only one complete costal fossa, located in the middle of each lateral surface of the vertebral body.

The arches of the thoracic vertebrae form rounded vertebral foramina, but relatively smaller than those of the cervical vertebrae.
The transverse process is directed outward and somewhat posteriorly and has a small costal fossa of the transverse process, fovea costalis processus transversus, articulated with the tubercle of the rib.

The articular surface of the articular processes lies in the frontal plane and is directed posteriorly at the upper articular process, and anteriorly at the lower one. The spinous processes are long, triangular, pointed and directed downwards. The spinous processes of the middle thoracic vertebrae are located one above the other in a tiled manner.

The lower thoracic vertebrae are similar in shape to the lumbar vertebrae. On the posterior surface of the transverse processes of the 11th - 12th thoracic vertebrae there is an additional process, processus accessorius, and a mastoid process, processus mamillaris.

Lumbar vertebrae

The lumbar vertebrae, vertebrae lumbales (Fig. 24 - 27; see Fig. 7), number 5 (L1-L5), differ from the others in their massiveness. The body is bean-shaped, the arches are strongly developed, the vertebral foramen is larger than that of the thoracic vertebrae, and has an irregular triangular shape.

Fig.24. Third lumbar vertebra, vertebra lumbalis; view from above

Fig.25. Third lumbar vertebra, vertebra lumbalis; right view

Fig.27. Lumbar part of the spinal column; Front view (x-ray).
1 – 12th thoracic vertebra; 2 – 12th rib;
3 – costal process; 4 – articular process;
5 – spinous process; 6 – articular process;
7 – 1st lumbar vertebra.

Fig.28. Sacrum, os sacrum; front view (pelvic surface, facies pelvica.)

Each transverse process, located in front of the articular one, is elongated, compressed from front to back, running laterally and somewhat posteriorly. Its largest part - the costal process, processus costalis - is a rudimentary rib. On the posterior surface of the base of the costal process there is a weakly defined dorsal process, processus accessorius, a rudiment of the transverse process.

The spinous process is short and wide, thickened and rounded at the end. The articular processes, starting from the arch, are directed posteriorly from the transverse and are located almost vertically. The articular surfaces lie in the sagittal plane, with the upper concave and facing medially, and the lower convex and facing laterally.

When two adjacent vertebrae articulate, the upper articular processes of one vertebra laterally cover the lower articular processes of the other. On the posterolateral edge of the superior articular process there is a small mastoid process, processus mamillaris, a trace of muscle attachment

Sacrum

The sacral vertebrae, vertebrae sacrales, number 5, fuse in an adult into a single bone - the sacrum.

The sacrum, os sacrum (sacrale) (Fig. 28 - 33; see Fig. 7), has a wedge shape, is located under the last lumbar vertebra and is involved in the formation of the posterior wall of the pelvis. The bone is divided into a pelvic and dorsal surface, two lateral parts, a base (the wide part facing up) and an apex (the narrow part facing down).

The anterior surface of the sacrum is smooth, concave, facing the pelvic cavity - this is the pelvic surface, facies pelvica (see Fig. 28). It preserves traces of the fusion of the bodies of the five sacral vertebrae in the form of four parallel transverse lines, lineae transversae. Outside of them, on each side, there are four anterior pelvic sacral foramina, foramina sacralia anteriora (pelvica) (the anterior branches of the sacral spinal nerves and the accompanying vessels pass through them).

Fig. 29 Sacrum, os sacrum; back view.
(Dorsal surface, facies dorsalis.)

The dorsal surface of the sacrum, facies dorsalis sacri (see Fig. 29), is convex in the longitudinal direction, narrower than the anterior one and rough. It contains five bone ridges running side by side from top to bottom, formed as a result of the fusion of the spinous, transverse and articular processes of the sacral vertebrae.

Fig. 30 Sacrum, os sacrum; right view

Fig. 31 Sacrum, os sacrum; right view.
(Mid-longitudinal cut.)

The median sacral ridge, crista sacralis mediana, was formed from the fusion of the spinous processes of the sacral vertebrae and is represented by four tubercles located one above the other, sometimes merging into one rough ridge.

On each side of the median sacral crest, almost parallel to it, there is one weakly defined intermediate sacral crest, crista sacralis intermedia. The ridges were formed as a result of the fusion of the superior and inferior articular processes. Outside of them there is a well-defined row of tubercles - the lateral sacral ridge, crista sacralis lateralis, which is formed by the fusion of the transverse processes. Between the intermediate and lateral ridges there are four posterior sacral foramina, foramina sacralia posteriora; they are somewhat smaller than the corresponding anterior sacral foramina (the posterior branches of the sacral nerves pass through them).

Along the entire length of the sacrum follows the sacral canal, canalis sacralis, of a curved shape, widened at the top and narrowed at the bottom; it is a direct continuation downward of the spinal canal. The sacral canal communicates with the sacral foramina through the intervertebral foramina, foramina intervertebralia, located inside the bone (see Fig. 31).

The base of the sacrum, basis ossis sacri (see Fig. 28, 33), has a transverse oval-shaped depression - the junction with the lower surface of the body of the 5th lumbar vertebra. The anterior edge of the base of the sacrum at the junction with the 5th lumbar vertebra forms a promontory - a promontory, promontorium (see Fig. 7), strongly protruding into the pelvic cavity. From the posterior part of the base of the sacrum, the upper articular processes, processus articulares superiores, of the 1st sacral vertebra extend upward. Their articular surfaces, facies articulares, are directed backward and medially and articulate with the lower articular processes of the 5th lumbar vertebra. The posterior edge of the base (arch) of the sacrum with the superior articular processes protruding above it limits the entrance to the sacral canal.

The apex of the sacrum, the arex ossis sacri, is narrow, blunt and has a small oval platform - the junction with the upper surface of the coccyx; here the sacrococcygeal joint, articulatiosacrococcygea (see Fig. 224), is formed, well expressed in young people, especially in women.
Behind the apex, on the posterior surface of the sacrum, the intermediate ridges end in two small protrusions directed downwards - the sacral horns, cornua sacralia. The posterior surface of the apex and the sacral horns limit the outlet of the sacral canal - the sacral fissure, hiatus sacralis.

The upper outer part of the sacrum - the lateral part, pars lateralis, was formed by the fusion of the transverse processes of the sacral vertebrae.
The upper, flattened, triangular-shaped surface of the lateral part of the sacrum, the anterior edge of which passes into the boundary line, is called the sacral wing, ala sacralis (see Fig. 28, 32).

Fig. 32 Sacrum, os sacrum; view from above

Fig. 33 Sacrum, os sacrum. (Horizontal
cut at the level of the 2nd sacral vertebra.)

The lateral surface of the sacrum - the articular auricular surface, facies auricularis (see Fig. 30), articulates with the surface of the ilium of the same name (see "Belt" lower limb").

Posterior and medial to the auricular surface is the sacral tuberosity, tuberositas sacralis, a trace of the attachment of the sacroiliac interosseous ligaments.

The sacrum in men is longer, narrower and more curved than in women.

Coccyx

The coccyx, os coccygis (Fig. 34, 35; see Fig. 7), is a bone fused in an adult from 4-5, less often from 3-6 vertebrae.

The coccyx has the shape of a curved pyramid, the base of which faces upward and the apex faces downward. The vertebrae that form it have only bodies. On 1 coccygeal vertebra on each side there are remnants of the upper articular processes in the form of small protrusions - coccygeal horns, cornua coccygea, which are directed upward and connect to the sacral horns.

The upper surface of the coccyx is slightly concave and connects to the apex of the sacrum through the sacrococcygeal joint.

Fig. 34 Coccyx, os coccygis. A – front view; B – rear view.

Fig. 35 Sacral and coccygeal parts of the spinal column (x-ray)
1 – 5th lumbar vertebra; 2 – sacrum;
3 – coccyx; 4 – pubic bone; 5 – pubic arch;
6 – ischium.

BONES OF THE CHEST

Re6pa

The ribs, costae (Fig. 36 - 39), 12 pairs, are narrow, curved bone plates of varying lengths, symmetrically located on the sides of the thoracic spinal column.

In each rib, there is a longer bony part of the rib, os costale, a short cartilaginous part - the costal cartilage, cartilago сostalis, and two ends - the anterior one, facing the sternum, and the posterior one, facing the spinal column.

The bony part of the rib has a head, neck and body. The head of the rib, carut costae, is located at its vertebral end. It has an articular surface of the rib head, facies articularis capitis costae. This surface on ribs 2–10 is divided by the horizontally running ridge of the rib head, crista capitis costae, into an upper, smaller, and lower, larger part, each of which respectively articulates with the costal fossae of two adjacent vertebrae.

The neck of the rib, collum costae, is the most narrowed and rounded part of the rib, bearing on the upper edge the crest of the neck of the rib, crista colli costae (ribs 1 and 12 do not have this crest).

At the border with the body at the 10 upper pairs of ribs on the neck there is a small tubercle of the rib, tuberculum costae, on which there is an articular surface of the tubercle of the rib, facies articularis tuberculi costae, articulating with the transverse costal fossa of the corresponding vertebra.

Between the posterior surface of the rib neck and the anterior surface of the transverse process of the corresponding vertebra, a costotransverse foramen, foramen costotransversarium, is formed (see Fig. 44).
The body of the rib, corpus costae, extending from the tubercle to the sternal end of the rib, is the longest section of the bony part of the rib. At some distance from the tubercle, the body of the rib, bending strongly, forms the angle of the rib, angulus costae. In 1 rib (see Fig. 36, A) it coincides with the tubercle, and on the remaining ribs the distance between these formations increases (up to the 11th rib); body 12 does not form an angle edge. The body of the rib is flattened throughout. This allows us to distinguish between two surfaces: the inner, concave, and the outer, convex, and two edges: the upper, rounded, and the lower, sharp. On the inner surface along the lower edge there is a rib groove, sulcus costae (see Fig. 37), where the intercostal artery, vein and nerve lie. The edges of the ribs describe a spiral, so the rib is twisted around its long axis.

At the anterior sternal end of the bony part of the rib there is a fossa with a slight roughness; The costal cartilage is attached to it.

The costal cartilages, cartilagines costales (there are also 12 pairs of them), are a continuation of the bony parts of the ribs. From ribs 1 to 11, they gradually lengthen and connect directly to the sternum. The upper 7 pairs of ribs are true ribs, costae verae, the lower 5 pairs of ribs are false ribs, costae spuriae, and the 11th and 12th ribs are fluctuating ribs, costae fluitantes. The cartilages of the 8th, 9th and 10th ribs do not directly approach the sternum, but each of them is attached to the cartilage of the overlying rib. The cartilages of the 11th and 12th ribs (sometimes 10) do not reach the sternum and with their cartilaginous ends lie freely in the muscles of the abdominal wall.

Some features have two first and two last pairs of edges. The first rib, costa prima (1) (see Fig. 36, A), is shorter, but wider than the others, has almost horizontally located upper and lower surfaces (instead of the outer and inner ones of the other ribs). On the upper surface of the rib, in the anterior section, there is a tubercle of the anterior scalene muscle, tuberculum m. scaleni anterioris (place of attachment of the specified muscle). Outside and posterior to the tubercle lies a shallow groove of the subclavian artery, sulcus a. subclaviae (a trace of the artery of the same name lying here, a. subclavia), behind which there is a small roughness (the place of attachment of the middle scalenus muscle, i.e. scalenus medius). Anterior and medially from the tubercle there is a faint groove of the subclavian vein, sulcus v. subclaviae. The articular surface of the head of the 1st rib is not divided by a ridge; the neck is long and thin; the costal angle coincides with the tubercle of the rib.

The second rib, costa secunda (see Fig. 36, B), has a roughness on the outer surface - the tuberosity of the serratus anterior muscle, tuberositas m. serrati anterioris (place of attachment of the tooth of the specified muscle).

The eleventh and twelfth ribs, costa 11 et costa 12 (see Fig. 39), have articular surfaces of the head not separated by a ridge. On the 11th rib, the angle, neck, tubercle and costal groove are weakly expressed, and on the 12th they are absent.

Sternum

The sternum, sternum (Fig. 40, 41), is an unpaired bone of an elongated shape with a slightly convex anterior surface and a correspondingly concave posterior surface. The sternum occupies a section of the anterior wall of the chest. It distinguishes the manubrium, body and xiphoid process. All these three parts are connected to each other by cartilaginous layers, which ossify with age.

The manubrium sterni, the widest part, thick at the top, thinner and narrower at the bottom, has a jugular notch on the upper edge, incisura jugularis, easily palpable through the skin. On the sides of the jugular notch are the clavicular notches, incisurae claviculares, the places of articulation of the sternum with the sternal ends of the clavicles.

Somewhat lower, on the lateral edge, there is the notch of the 1st rib, incisuga costalis, - the place of fusion with the cartilage of the 1st rib. Even lower there is a small depression - the upper section of the costal notch 2 ribs; the lower portion of this notch is located on the body of the sternum.

The body of the sternum, corpus sterni, is almost 3 times longer than the manubrium, but narrower. The body of the sternum is shorter in women than in men.

Fig.40 Sternum, sternum; front view

Fig.41 Sternum, sternum; right view

The anterior surface of the sternum has traces of the fusion of its parts during embryonic development in the form of weakly expressed transverse lines.

The cartilaginous connection of the upper edge of the body with the lower edge of the manubrium is called synchondrosis of the manubrium of the sternum, synchondrosis manubriosternalis (see Fig. 235), while the body and the manubrium converge, forming an obtuse angle of the sternum, open posteriorly, angulus sterni. This protrusion is located at the level of the articulation of the 11th rib with the sternum and can be easily felt through the skin.

On the lateral edge of the body of the sternum there are four complete and two incomplete costal notches, incisurae costales, the places of articulation of the sternum with the cartilages of ribs 2–7. One incomplete notch is located at the top of the lateral edge of the sternum and corresponds to the cartilage of the 11th rib, the other is at the bottom of the lateral edge and corresponds to the cartilage of the 7th rib; four complete notches lie between them and correspond to 3 - 6 ribs.

The areas of the lateral sections lying between two adjacent costal notches have the shape of semilunar recesses.

The xiphoid process, processus xiphoideus, is the shortest part of the sternum, can be different in size and shape, with a forked apex or with a hole in the middle. The sharp or blunt apex faces either anteriorly or posteriorly. In the superolateral section of the xiphoid process there is an incomplete notch that articulates with the cartilage of the 7th rib.

The xiphoid process forms with the body of the sternum synchondrosis of the xiphoid process, synchondrosis xiphosternalis (see Fig. 235). By old age, the xiphoid process, ossified, fuses with the body of the sternum.

Sometimes above the manubrium of the sternum, in the thickness of the subhyoid muscle group or in the medial leg of the sternocleidomastoid muscle, there are 1-3 sternum bones, ossa suprasternalia. They articulate with the manubrium of the sternum.

RIB CAGE

The chest, compages thoracis (Fig. 42 - 45), consists of the thoracic spinal column, ribs (12 pairs) and sternum.

The chest forms the chest cavity, cavitas thoracis, which has the shape of a truncated cone, with its wide base facing downward and its truncated apex facing upward.

Fig. 42 Chest, compages thoracis; front view

Fig. 43 Chest, compages thoracis; back view

In the chest there are anterior, posterior and lateral walls, an upper and lower opening, which limit the chest cavity.

The anterior wall is shorter than the other walls, formed by the sternum and cartilage of the ribs. Positioned obliquely, it protrudes more anteriorly with its lower sections than with its upper ones. The posterior wall is longer than the anterior one, formed by the thoracic vertebrae and sections of the ribs from the heads to the corners; its direction is almost vertical.

On the outer surface of the posterior wall of the chest, between the spinous processes of the vertebrae and the corners of the ribs, two grooves are formed on both sides - dorsal grooves; they contain the deep muscles of the back. On the inner surface of the chest, between the protruding vertebral bodies and the corners of the ribs, two grooves are also formed - pulmonary grooves, sulci pulmonales, the lungs are adjacent to them with the vertebral part of the costal surface (see Fig. 44).

Fig.44 Thoracic segment (x-ray).
Relationship of ribs to vertebra 4 and sternum.

Fig.45 Chest; front view.
1 – left clavicle; 2 – descending aorta; 3 – gate
lung; 4 – pulmonary trunk; 5 – heart; 6 – left
lung; 7 – diaphragm (left dome); 8 – diaphragm
(right dome); 9 – ascending aorta; 10 – top
right lung; 11 – aortic arch; 12 – rib (posterior
Part); 13 – right clavicle; 14 – right shoulder blade;
15 – left shoulder blade; 16 – rib (front)

The lateral walls are longer than the front and back, formed by the bodies of the ribs and are more or less convex. The spaces bounded above and below by two adjacent ribs, in front by the lateral edge of the sternum and behind by the vertebrae, are called intercostal spaces, spatia intercostalia; they are made of ligaments, intercostal muscles and membranes.

The chest, compages thoracis, bounded by the indicated walls, has two openings - upper and lower, which are called apertures.

The upper aperture of the chest, apertura thoracis superior (see Fig. 133), is smaller than the lower one, limited in front by the upper edge of the manubrium, on the sides by the first ribs and behind by the body of the 1st thoracic vertebra. It has a transverse oval shape and is located in a plane inclined from back to front and downwards. The upper edge of the manubrium of the sternum is located at the level of the gap between the 2nd and 3rd thoracic vertebrae.

The lower aperture of the chest, apertura thoracis inferior, is limited in front by the xiphoid process and the costal arch formed by the cartilaginous ends of the false ribs, on the sides by the free ends of the 11th and 12th ribs and the lower edges of the 12th ribs, and behind by the body of the 12th thoracic vertebra.

The costal arch, arcus costalis, at the xiphoid process forms an open substernal angle, angulus infrasternalis (see Fig. 42).

The shape of the chest varies from person to person (flat, cylindrical, or conical). In persons with a narrow chest, the infrasternal angle is sharper and the intercostal spaces are wider, and the chest itself is longer than in persons with a wide chest. The chest of men is longer, wider and more cone-shaped than that of women. The shape of the chest also depends on age.

FIBROUS COMPOUNDS

Fibrous compounds, articulationes fibrosae (Fig. 216), provide continuous connection of bones due to various types connective tissue: dense, connective, cartilage or bone tissue.

Fibrous joints formed by dense connective tissue include syndesmoses, sutures, and impactions.

Syndesmoses, syndesmoses, include ligaments, which are connections between bones made of dense connective tissue. For example, the pterygospinous ligament, lig. pterygospinale, starts from the spine of the sphenoid bone and attaches to the pterygospinous process, located on the lateral plate of the pterygoid process; stylohyoid ligament, lig. stylohyoideum, thin and long, starts from the styloid process and, going down and anteriorly, is attached to the small horns of the hyoid bone, etc. Sometimes syndesmoses can contain a significant amount of elastic fibers, such as the yellow ligament, ligg. f1ava, located between the vertebral arches, nuchal ligament, lig. nuchae, etc. In addition, syndesmoses are broad ligaments that connect bones over a considerable distance: interosseous membranes of the forearm and lower leg, membrana interossea antebrachii, membrana interossea cruris. Syndesmoses also include the fontanelles of the skull, built from primary connective tissue.

Seams, suturae, connect the bones of the cranial vault and face. They are formed by short strands of dense connective tissue running between the edges of adjacent bones and penetrating into them. With age, ossification of the sutures occurs due to the replacement of dense connective tissue with bone tissue. Based on the relief of the sutures and the method of applying the connecting edges of the bones, the following types of sutures are distinguished: serrated suture, sutura serrata; scaly suture, sutura squamosa; flat seam, sutura plana. The bones of the cranial vault are connected by scaly and serrated sutures. The bones of the face are often joined by a flat suture, ensuring precise and even alignment of the edges. In addition, there is a suture in the form of schindylosis (splitting), schyndilesis, - this is the connection of the edge of one bone with the groove of another, as in the formation of the wedge-vomer suture sutura sphenovomeriana.

3uboalveolar connections, articulationes dentoalveolares (gomphosis), occur when the roots of a tooth, covered with periodontium, connect with the alveolus. Here, bands of dense connective tissue hold the teeth in the dental alveoli. With age, this connection weakens, and the teeth become loose (see T.2 “Digestive system”).

Cartilage joints, articulationes cartilagineae, are a type of fibrous joints formed by cartilage tissue. Among the cartilaginous joints, synchondroses and symphyses are distinguished.

Synchondroses, synchondroses, are formed by continuous layers of cartilage that connect the edges of bones and limit movement. They are widespread in the skeletal system of children and adolescents - they connect parts of bones (for example, the diaphysis of a long bone with the epiphyses, sacral vertebrae with each other, etc.). These are non-permanent synchondrosis; with age, cartilage tissue is replaced by bone. Synchondroses that persist in the skeletal system of an adult include synchondrosis of the skull (sphenoid-occipital, sphenoid-petrosal, petrooccipital, sphenoid-ethmoid) and synchondrosis of the sternum (synchondrosis of the manubrium and xiphoid process).

Fig. 216 Fibrous compounds, articulationes fibrosae

Syndesmos, syndesmosis: 1a – yellow ligaments, ligg. flava; 1b – interosseous membrane of the forearm, membrana interossea antebrachii. Seam, sutura: 2a – jagged seam, sutura serrata; 2b – scaly suture, sutura squamosa; 2c – flat seam, sutura plana. Synchondrosis, synchondrosis: 3a – synchondrosis of the manubrium of the sternum, synchondrosis manubriosternalis; 3b – synchondrosis of the xiphoid process, synchondrosis xiphosternalis; 3c – sphenooccipital synchondrosis, synchondrosis sphenooccipitalis; 4 – dentoalveolar junction, gomphosis (articulatio dentoalveolaris). Symphysis, symphysis: 5a – intervertebral symphysis, symphysis intervertebralis; 5b – pubic symphysis, symphysis pubica.

Symphyses, symphyses, are formed by fibrous cartilage, and there is a cavity inside the cartilaginous plate. Such connections are observed between the vertebral bodies - the intervertebral symphysis, symphysis intervertebralis (see Fig. 219), the symphysis of the manubrium, symphysis manubriosternalis, (see Fig. 235), and the pubic symphysis, symphysis pubica (see Fig. 259).

SYNOVIAL JOINTS (JOINTS)

Discontinuous connections of bones - joints, or synovial joints, articulationes synoviales (Fig. 217), are the most common type of articulation of human bones, creating conditions for high mobility of the body. A joint is called simple, articulatio simplex, if two bones are involved in its formation, and complex, articulatio composita, if it is formed by three or more bones.

Fig.217. Synovial joints (joints). Types of joints according to shape and number of axes of rotation. Uniaxial joints; 1a, 1b – trochlear joints, ginglimus (a – articulatio talocruralis; b – articulatio interphalangea manus); 1c – cylindrical joint, articulatio trochoidea (articulation radioulnaris proximalis). Biaxial joints: 2a – elliptical joint, articulatio ellipsoidea (articulatio radiocarpea); 2b – condylar joint (articulatio genus); 2c – saddle joint, articulatio sellaris (articulatio carpometacarpea pollicis). Triaxial joints: 3a – spherical joint, ariculatio spheroidea (articulation humari); 3b – cup-shaped joint, articulatio cotylica (articulatio coxae); 3c – flat joint, articulatio plana (articulatio sacroiliaca).

Each joint has obligatory structural elements, without which the connection of bones cannot be classified as joints, and auxiliary formations that determine the structural and functional differences of one joint from others.

TO mandatory elements joint includes articular cartilage covering the articular surfaces; articular capsule and articular cavity.

Articular cartilage, cartilago articulares, usually built of hyaline cartilage, less often fibrous. These cartilages cover the surfaces of the bones that face each other when the articulating bones face each other. Consequently, one surface of the articular cartilage is fused with the bone surface it covers, and the other is free to stand in the joint.

Joint capsule, capsula articularis, surrounds the articulating ends of the bones in the form of a closed sheath and, without moving onto the articular surfaces, continues into the periosteum of these bones. The capsule is built from fibrous connective tissue and consists of two layers - membranes. The outer, fibrous membrane, membrana fibrosa (stratum fibrosum), is built from dense fibrous connective tissue and plays a mechanical role. From the inside, it passes into the synovial membrane, membrana synovialis (stratum synoviale). The synovial membrane forms synovial folds, plicae synoviales. This membrane secretes synovial fluid (synovia) into the joint, which wets the articular surfaces of the bones, nourishes the articular cartilage, acts as a shock absorber, and also changes the mobility of the joint as its viscosity changes. The working surface of the membrane increases not only due to synovial folds, but also due to synovial villi, vilii synoviales, facing the articular cavity.

Articular cavity, cavitas articularis, is a narrow closed gap limited by the articulating surfaces of the bones and the articular capsule and filled with synovial fluid. The cavity has no communication with the atmosphere.

Auxiliary formations of joints are varied. These include ligaments, ligamenta; articular discs, disci articulares; articular menisci, menisci articulares; articular lips, labra articularia.

Joint ligaments- these are bundles of dense fibrous connective tissue that strengthen the joint capsule and limit or guide the movement of bones in the joint. In relation to the articular capsule, extracapsular ligaments, ligg, are distinguished. extracapsularia, located outside the articular capsule, capsular ligaments, ligg. capsularia, located in the thickness of the capsule, between its fibrous and synovial membranes, and intracapsular ligaments, ligg. intracapsularia, inside the joint. Almost all joints have ligaments. Extracapsular ligaments are woven into the outer sections of the fibrous layer of the capsule; capsular ligaments are a thickening of this layer, and intracapsular ligaments are intra-articular in position, but are covered with a synovial membrane that separates them from the joint cavity.

Replacement disks- these are layers of hyaline or fibrous cartilage wedged between the articular surfaces of bones. They are attached to the joint capsule, and divide the articular cavity into two floors. Discs increase the correspondence (congruence) of the articular surfaces, and, consequently, the volume and variety of movements. In addition, they serve as shock absorbers, reducing shocks and shocks when moving. Such discs are found, for example, in the sternoclavicular and temporal joints.

Articulated menisci unlike discs, these are not solid cartilaginous plates, but crescent-shaped formations of fibrous cartilage. Two menisci, right and left, are located in each knee joint; they are attached with the outer edge to the capsule, closer to tibia, and the sharp inner edge will stand freely in the joint cavity. The menisci diversify movements in the joint and serve as shock absorbers.

Articular labrum formed by dense fibrous connective tissue. It attaches to the edge of the glenoid cavity and deepens it, increasing the conformity of the surfaces. The lip faces the joint cavity (shoulder and hip joints).

Joints differ in the shape of the articular surfaces and the degree of mobility of the articulating bones. Based on the shape of the articular surfaces, the following are distinguished: spherical (cup-shaped) joints, articulationes spheroideae (cotylicae); flat, articulationes pianae; ellipsoid, articulationes ellipsoidae (condylares); saddle-shaped, articulationes sellares; ovoids, articulationes ovoidales; cylindrical, articulationes trochoideae; block-shaped, ginglymus; condylar, articulationes bicondylares.

The nature of movement in the joint depends on the shape of the articular surfaces (see Fig. 217). Ball-shaped and flat joints, in which the generatrix is ​​represented by a segment of a circle, allow movement around three mutually perpendicular axes: frontal, anteroposterior (sagittal) and vertical. So, in shoulder joint, spherical in shape, flexion (f1exio) and extension (extensio) are possible around the frontal axis, while movement occurs in the sagittal plane; around the anteroposterior axis - abduction (abductio) and adduction (adductio), the movement occurs in the frontal plane. Finally, rotation (rotatio) is possible around the vertical axis, including rotation inward (pronatio) and outward (supinatio), and the rotation itself is carried out in the horizontal plane. These movements in flat joints are very limited (the flat articular surface in this case is considered as a small segment of a circle of large diameter), and in spherical joints the movements are performed with a large amplitude and are supplemented by circular motion (circumductio), in which the center of rotation corresponds to the spherical joint, and the moving bone describes the surface of the cone.

Joints in which movement around one of the three axes is excluded and only possible around two axes are called biaxial. Biaxial joints include ellipsoid joints (for example, the wrist joint) and saddle joints (for example, the carpometacarpal joint of the 1st finger).

Uniaxial and cylindrical and trochlear joints are considered. In a cylindrical joint, the generatrix moves parallel to the axis of rotation. An example of such a joint is the atlantoaxial median joint, the axis of rotation in which runs vertically through the tooth of the 2nd cervical vertebra, as well as the proximal radioulnar joint.

A type of uniaxial joint is block-shaped, in which the generatrix is ​​inclined relative to the axis of rotation (as if beveled). These joints include the humeroulnar and interphalangeal joints.

Condylar joints, articulationes bicondylares, are modified elliptical joints.

In some joints of the skeletal system, movements are possible only simultaneously with movements in neighboring joints, i.e. anatomically isolated joints are united by a common function. This functional combination of joints must be taken into account when studying their structure and analyzing the structure of movements.

CONNECTIONS OF THE BONES OF THE TORSO AND SKULL

CONNECTIONS OF THE TORSO BONES

Spinal joints

Individual vertebrae are connected to each other through connections of different types, forming the spinal column, columna vertebralis.
These connections are: cartilaginous joints, articulationes cartilagineae, forming the intervertebral symphysis, symphysis intervertebralis, represented by intervertebral discs, disci intervertebrales, connecting the vertebral bodies; joints of the spine, articulationes vertebrales, including the facet joints, articulationes zygapophysiales, lumbosacral joint, articulatio lumbosacralis, and sacrococcygeal joint, articulatio sacrococcygea. All these connections are strengthened by a large number of ligaments stretched between the bodies, arches and processes of the vertebrae, ligaments of the spinal column, ligg. columnae vertebralis.

Intervertebral symphysis

The intervertebral symphysis, symphysis intervertebralis (Fig. 218 - 221), is represented by intervertebral discs (cartilage) lying between the bodies of two adjacent vertebrae throughout the cervical, thoracic and lumbar sections of the spinal column.

The intervertebral disc, discus intervertebralis (see Fig. 218 - 221, 225), belongs to the group of fibrous cartilage. It consists of a peripheral part - the fibrous ring, anulus fibrosus, and a centrally located nucleus pulposus, nucleus pulposus.

Fig. 218 Intervertebral discs, disci intervertebrales; front view

Fig. 219 Sagittal section of the lumbar
vertebrae (L4 – L5) and intervertebral disc
(photo).1 – fibrous ring, anulus fibrosus; 2 – nucleus pulposus, nucleus pulposus

There are three directions in the orientation of the collagen fibers forming the fibrous ring: concentric, oblique (crossing) and spiral. All fibers are lost at their ends in the periosteum of the vertebral bodies. The central part of the intervertebral disc - the nucleus pulposus - is very elastic and is a kind of springy layer, which, when the spine is tilted, shifts towards extension. On a section of the intervertebral disc, the nucleus pulposus, compressed under normal conditions, protrudes above the surface of the annulus fibrosus. The nucleus pulposus can be solid (see Fig. 225, A) or have a small slit-like cavity (see Fig. 225, B).
The transition of the fibrous ring to the nucleus pulposus is gradual. Toward the center of the disc in its tissue, the number of fibers in the intercellular substance decreases, but the mass of the ground substance increases. Until the age of 20, the nucleus pulposus is well defined, and then, with age, it is replaced by fibrous connective tissue growing from the fibrous ring. The intervertebral disc fuses with the hyaline cartilage covering the surfaces of the vertebral bodies facing each other, and its shape corresponds to the shape of these surfaces. There is no intervertebral disc between the atlas and the axial vertebra. The thickness of the discs is not the same and gradually increases towards the lower part of the spinal column, and the discs of the cervical and the lumbar spine is somewhat thicker in front than in the back. In the middle part of the thoracic spine, the discs are much thinner than in the higher and lower parts. The cartilaginous section makes up a quarter of the length of the entire spinal column.

Facet joints

The facet joints, articulationes zygapophysiales (see, Fig. 220, 221, 226), are formed between the upper articular process, processus articularis superior, of the underlying vertebra and the lower articular process, processus articularis inferior, of the overlying vertebra. The articular capsule is strengthened along the edge of the articular cartilage. The articular cavity is located according to the position and direction of the articular surfaces, approaching the horizontal plane in the cervical region. in the thoracic region - to the frontal and in the lumbar region - to the sagittal plane. The facet joints in the cervical and thoracic parts of the spinal column are classified as flat joints; in the lumbar spine they are classified as cylindrical. Functionally, they belong to the group of low-moving joints.

Symmetrical facet joints are combined joints, i.e., those in which movement in one joint necessarily entails displacement in the other, since both joints are formations of articular processes on the same bone.

Ligaments of the spinal column, ligg. сlumnae verlebralis, can be divided into long and short (Fig. 222 - 227).

To the group of long ligaments The spinal column includes the following:

1.Anterior longitudinal ligament. lig. longitudinale anterius (see Fig. 221,224,226), runs along the anterior surface and partly along the lateral surfaces of the vertebral bodies along the length from the anterior tubercle of the atlas to the sacrum, where it is lost in the periosteum of the 1st and 2nd sacral vertebrae. The anterior longitudinal ligament in the lower parts of the spinal column is significant; wider and stronger. It connects loosely with the vertebral bodies and tightly with the intervertebral discs, since it is woven into the perichondrium (perichondrium) covering them; on the sides of the vertebrae it continues into their periosteum. The deep layers of the bundles of this ligament are somewhat shorter than the superficial ones, due to which they connect adjacent vertebrae with each other, and the superficial, longer bundles lie over 4 - 5 vertebrae. The anterior longitudinal ligament limits excessive extension of the spinal column,

2. 3rd posterior longitudinal ligament, lig. longitudinale posterius (Fig. 228; see Fig. 224, 227), located on the posterior surface of the vertebral bodies in the spinal canal. It originates on the posterior surface of the axial vertebra, and at the level of the two upper cervical vertebrae it continues into the integumentary membrane, membrana tectoria. Inferiorly, the ligament reaches the initial section of the sacral canal. The posterior longitudinal ligament, in contrast to the anterior one, is wider in the upper part of the spinal column than in the lower part. It is firmly fused with the intervertebral discs, at the level of which it is somewhat wider than at the level of the vertebral bodies. It is loosely connected to the vertebral bodies, and the venous plexus lies in the layer of connective tissue between the ligament and the vertebral body. The superficial bundles of this ligament, like the anterior longitudinal ligament, are longer than the deep ones.

The group of short ligaments of the spinal column is a syndesmosis. These include the following links:

2. Ligamentum flavum, ligg. flava (Fig. 229; see Fig. 220, 223, 224), fill the spaces between the vertebral arches from the axial vertebra to the sacrum. They are directed from the inner surface and lower edge of the arch of the overlying vertebra to the outer surface and upper edge of the arch of the underlying vertebra and, with their anterior edges, limit the intervertebral foramina from behind.

Rice. 220. Facet joints; view from above
(III lumbar vertebra. Connections between the II and III lumbar vertebrae; horizontal cut.)

Rice. 221. Ligaments and joints of the spinal column; right view

The ligamentum flavum consists of vertically running elastic bundles that give them their yellow color. They reach greatest development in the lumbar region. The yellow ligaments are very elastic and elastic, therefore, when the torso is extended, they shorten and act like muscles, keeping the torso in a state of extension and reducing muscle tension. When flexing, the ligaments are stretched and thereby also reduce the tension of the erector torso muscle (see back muscles). The ligamentum flavum is absent between the arches of the atlas and axial vertebra. Here, a covering membrane is stretched, which with its anterior edge limits the intervertebral foramen behind, through which the second cervical nerve exits.

2. Interspinous ligaments, ligg. interspinalia (see Fig. 221. 226) - thin plates that fill the spaces between the spinous processes of two adjacent vertebrae. They reach their greatest power in the lumbar spine and are least developed between the cervical vertebrae. In front they are connected to the yellow ligaments, and behind, at the apex of the spinous process, they merge with the supraspinous ligament.

3. Supraspinous ligament, lig. supraspinale (see Fig. 221), is a continuous cord running along the tops of the spinous processes of the vertebrae in the lumbar and thoracic regions. Below, it is lost on the spinous processes of the sacral vertebrae; above, at the level of the protruding vertebra (C7), it passes into the rudimentary nuchal ligament.

4. Nuchal ligament, lig. nuchae (see Fig. 226) is a thin plate consisting of elastic and connective tissue bundles. It is directed from the spinous process of the protruding vertebra (C7) along the spinous processes of the cervical vertebrae upward and, slightly expanding, attaches to the external occipital crest and the external, occipital protrusion; has the shape of a triangle.
5. Intertransverse ligaments. ligg. intertransversaria (see Fig. 222), are thin bundles, weakly expressed in the cervical and partly thoracic regions and more developed in the lumbar region. These paired ligaments connecting the tops of the transverse processes of adjacent vertebrae limit the lateral movements of the spine in the opposite direction. In the cervical region they may be bifurcated or absent.

Fig.222. Ligaments and joints of the spinal column, ligg. et articulations columnae vertebralis; back view. (Lumbar. The arches and processes of the 12th thoracic, 1st and 2nd lumbar vertebrae have been removed.)

The lumbosacral joint, articulatio lumbosacralis (see Fig. 224, 261), is formed between the 5th lumbar vertebra and the base of the sacrum. The joint is a modified intervertebral disc with an expanded cavity, the dimensions of which are much larger than in the overlying discs (see Fig. 261). Above and below, the cavity extends to the hyaline plates covering the vertebral bodies. The intervertebral disc of this connection has a higher anterior edge, which, together with the base of the sacrum and the inferoanterior section of the body of the 5th lumbar vertebra, forms a promontory (see Fig. 224). The lumbosacral joint is strengthened mainly by the iliopsoas ligament. lig. iliolumbale (see Fig. 259, 260), which comes from the posterosuperior edge of the iliac fossa and the posterior third of the iliac crest and is attached to the anterolateral surface of the body of the 5th lumbar and 1st sacral vertebrae. In addition, the joint is strengthened by the anterior and posterior longitudinal ligaments, which descend respectively along the anterior and posterior surfaces of the vertebral bodies.

Fig.223. Ligaments of the spinal column, ligg.
columnae vertebralis; front view. (Lumbar-
department Front cut, removed
bodies of 1st and 2nd lumbar vertebrae.)

Fig.224. Lumbosacral joint aticulatio
lumbosacralis, and sacrococcygeal
joint, articulatio sacrococcygea.
(Sagittal-median cut.)

Fig.225. Intervertebral discs (preparation by N. Sak; photograph). (Horizontal sections at the level of the middle of the disc.) 1 – fibrous ring, annulus fibrosus; 2 – nucleus pulposus, nucleus pulposus; 3 – cavity of the intervertebral disc of the lumbosacral joint.

Sacrococcygeal joint

The sacrococcygeal joint, articulatio sacrococcygea, is formed by the bodies of the 5th sacral and 1st coccygeal vertebrae, connected by a modified intervertebral disc with an expanded cavity (see Fig. 224. 261). This joint is strengthened by the following ligaments (see Fig. 224, 259, 260) :

1. Lateral sacrococcygeal ligament, lig. sacrococcygeum laterale, stretches between the transverse processes of the last sacral and 1st coccygeal vertebrae and is a continuation of the lig. intertransversarium.

2. Anterior sacrococcygeal ligament, lig. sacrococcygeum anterius (ventrale), is a continuation of lig. longitudinale anterius. It consists of two bundles located on the anterior surface of the sacrococcygeal joint. Along the way, closer to the end of the coccyx, the fibers of these bundles intersect.

3. The superficial posterior sacrococcygeal ligament, lig.sacrococcygeum posterius superficiale (dorsale), stretches between the posterior surface of the coccyx and the lateral walls of the entrance to the sacral cap, covering its gap. It corresponds to the yellow and supraspinous ligaments of the spinal column.

4. Deep posterior sacrococcygeal ligament, lig. sacrococcygeum posterius (dorsale), profundum, is a continuation of lig. longitudinalis posterioris.

Synovial joints of the skull with the atlas and the atlas with the axial vertebra

Atlanto-occipital joint, articulatio atlanto-occipitalis (Fig. 230-232; see Fig. 227, 228), paired. It is formed by the articular surface of the occipital condyles, condyli occipitales, and the superior articular fossa of the atlas, fovea articularis superior. The longitudinal axes of the articular surfaces of the occipital bone and atlas converge somewhat anteriorly. The articular surfaces of the occipital bone are shorter than the articular surfaces of the atlas. The articular capsule is attached along the edge of the articular cartilage. Based on the shape of the articular surfaces, this joint belongs to the group of ellipsoidal, or condylar, joints.

Fig.226. Ligaments and joints of the spinal column, ligg. et articulationes columnae vertebralis; right view

In both, right and left, joints, which have separate articular capsules, movements occur simultaneously, i.e. they form one combined joint; Nodding (bending forward and backward) and slight lateral movements of the head are possible.
This connection differs:

1. Anterior atlanto-occipital membrane, membrana atlanto-occipitalis anterior (see Fig. 226, 227). It is stretched along the axes of the gap between the anterior edge of the foramen magnum and the upper edge of the anterior arch of the atlas; fused with the upper end of the lig. longitudinale anterius. Behind it is the anterior atlanto-occipital ligament, lig. atlanto-occipitalis anterior, stretched between the occipital bone and the middle part of the anterior arch of the atlas.

Fig.227. Ligaments and joints of the cervical vertebrae and occipital bone; inside view. (Sagittal-midline cut through the occipital bone and 1-4 cervical vertebrae.)

2. Posterior atlanto-occipital membrane, membrana atlanto-occipitalis posterior (see Fig. 226, 227, 229). It is located between the posterior edge of the foramen magnum and the upper edge of the posterior arch of the atlas. In the anterior section it has an opening through which blood vessels and nerves pass. This membrane is a modified ligamentum flavum. The lateral sections of the membrane are the lateral atlanto-occipital ligaments, ligg. atlanto-occipitalis lateralia.
When the atlas and axial vertebra articulate, three joints are formed - two paired and one unpaired.

The lateral atlantoaxial joint (see Fig. 226, 231), paired, is formed by the lower articular surfaces of the atlas and the upper articular surfaces of the axial vertebra. It belongs to the type of low-moving joints, since its articular surfaces are flat and even. In this joint, sliding occurs in all directions of the articular surfaces of the atlas in relation to the axial vertebra.

The median atlantoaxial joint, articulatio atlanto-axialis mediana (see Fig. 227. 228, 230, 232), is formed between the posterior surface of the anterior arch of the atlas (fovea dentis) and the tooth of the axial vertebra. In addition, the posterior articular surface of the tooth forms a joint with the transverse ligament of the atlas, lig. transversum atlantis.

Tooth joints belong to the group of cylindrical joints. In them, it is possible to rotate the atlas together with the head around the vertical axis of the tooth of the axial vertebra, i.e., rotate the head to the right and left.

Fig.228. Ligaments and joints of the cervical vertebrae and occipital bone; inside view. (Frontal cut, the posterior parts of the occipital bone and the arch of the 1st-5th cervical vertebrae were removed.)

Fig.229. Ligaments of the cervical vertebrae and occipital bone; back view

The ligamentous apparatus of the median atlantoaxial joint includes:

1. The integumentary membrane, membrane tectoria (see Fig. 227, 230, 232), which is a wide, rather dense fibrous plate stretched from the anterior edge of the foramen magnum to the body of the axial vertebra. This membrane is called the integumentary membrane because it covers the back (from the side of the spinal canal) of the tooth, the transverse ligament of the atlas and other formations of this joint. It is considered part of the posterior longitudinal ligament of the spinal column.

Fig. 230. Ligaments and joints of the cervical vertebrae and occipital bone; inside view. (The posterior portions of the occipital bone and the posterior arch of the atlas have been removed.)

Fig.231. Ligaments and joints of the cervical vertebrae and occipital bone; inside view

2. Cruciate ligament of the atlas, lig. cruciforme atlantis (see Fig. 230) consists of two beams - longitudinal and transverse. The transverse fascicle is a dense connective tissue cord stretched between internal surfaces lateral mass of the atlas. It is adjacent to the posterior articular surface of the tooth of the axial vertebra and strengthens it. This bundle is called the transverse ligament of the atlas, lig. transversum atlantis (see Fig. 230, 232). Longitudinal beams. fasciculi longitudinales, consist of two, upper and lower, legs. The superior pedicle comes from the middle part of the transverse ligament of the atlas and reaches the anterior surface of the foramen magnum. The lower leg, which also starts from the middle part of the transverse ligament, is directed downward and attached to the posterior surface of the body of the axial vertebra.

Fig.232. Ligaments and joints of the atlas and axial vertebra; view from above. (Horizontal cut, the anterior arch and lateral masses of the atlas, and the tooth of the axial vertebra were partially removed.)

3. Ligament of the apex of the tooth, lig. apicis dentis (see Fig. 227, 231), stretches between the apex of the tooth of the axial vertebra and the middle part of the anterior edge of the large occipital
holes. This ligament is considered as a rudiment of the dorsal string (chord).

4. Pterygoid ligaments, ligg. alaria (see Fig. 230, 231), are formed by bundles of connective tissue fibers stretched between the lateral surfaces of the tooth of the axial vertebra and the inner surfaces of the occipital condyles, condyli occipitales.

Chest joints

The ribs are connected movably by their posterior ends with the bodies and transverse processes of the thoracic vertebrae through costovertebral joints, articulationes costovertebrales, and by their anterior ends - with the sternum by sternocostal joints, articulationes, sternocostales.

Costovertebral joints

The posterior ends of the ribs articulate with the vertebrae using two joints:

1. The joint of the rib head, articulatio capitis costae (Fig. 233; see Fig. 236), is formed by the articular surface of the rib head and the costal fossae of the vertebral bodies. The heads from 2 to 10 ribs are cone-shaped and come into contact with the corresponding articular fossae of the bodies of two vertebrae.

The articular surfaces on the vertebral bodies are in most cases formed by two fossae: the smaller upper costal fossa, fovea costalis superior, which is located in the lower part of the body of the overlying vertebra, and the larger lower costal fossa, fovea costalis inferior, lying at the upper edge of the lower vertebra. Ribs 1, 11 and 12 articulate only with the fossa of one vertebra. The articular surfaces of the costal fossae of the vertebrae and the heads of the ribs are covered with fibrous cartilage.

Fig.233. Ligaments and joints of ribs and vertebrae; view from above. (Horizontal cut, part of the 8th thoracic vertebra and 8th right rib was removed.)

In the cavity of the joints of ribs 2 - 10 lies the intra-articular ligament of the rib head, lig. capitis costae intraarticulare. It runs from the crest of the rib head to the intervertebral disc and divides the joint cavity into two chambers. The articular capsule is thin and is supported by the radiate ligament of the head of the rib, lig. capitis costae radiatum, which originates from the anterior surface of the rib head and is attached: fan-shaped to the above and underlying vertebrae and intervertebral disc.

2. The costotransverse joint, articulatio coostotransversaria, (Fig. 234; see Fig. 233, 236), is formed by the articulation of the articular surface of the tubercle of the rib, facies articularis tuberculi costae, with the costal fossa of the transverse processes of the thoracic vertebrae. These joints are present only in the 10 upper ribs. Their articular surfaces are covered with hyaline cartilage. The articular capsule is thin, attached along the edge of the articular surfaces.
The joint is strengthened by numerous ligaments:
a) superior costotransverse ligament, lig. costotransversarium superius, originates from the lower surface of the transverse process and attaches to the crest of the neck of the underlying rib;
b) lateral costotransverse ligament, lig. costotransversarium laterale, stretches between the bases of the transverse and spinous processes and the posterior surface of the neck of the underlying rib;
c) costotransverse ligament, 1ig. costotransversarium, lies between the posterior surface of the rib neck and the anterior surface of the transverse process of the corresponding vertebra, filling the costal opening, foramen costotransversarium (see Fig. 44, 233);
d) lumbocostal ligament, lig. lumbocostale, is a thick fibrous plate stretched between the costal processes of L1 and L2 and the lower edge of the 12th rib. It fixes the rib and at the same time strengthens the aponeurosis transverse muscle belly.

The joints of the head and tubercle of the rib are cylindrical joints in shape, and they are functionally connected: during the act of breathing, movements occur simultaneously in both joints.

Fig.234. Ligaments and joints of ribs and vertebrae; back view

Sternocostal joints

The anterior ends of the ribs end in costal cartilages. The bony part of the ribs is connected to the costal cartilages through the costochondral joints, articulationes costochondrales,
(Fig. 235), and the periosteum of the rib continues into the perichondrium of the corresponding costal cartilage, and the connection between them becomes saturated with lime with age. The costal cartilage of the 1st rib fuses with the sternum. The costal cartilages of ribs 2–7 articulate with the costal notches of the sternum, forming sternocostal joints, articulationes sternocostales (Fig. 236; see Fig. 235). The cavity of these joints is a narrow, vertically located gap, which in the cavity of the joint of the 2nd costal cartilage has an intra-articular sternocostal ligament, lig. sternocostale intraarticulare. It goes from the costal cartilage of the 2nd rib to the junction of the manubrium and the body of the sternum. In the cavities of other sternocostal joints, this ligament is weakly expressed or absent.

The articular capsules of these joints, formed by the perichondrium of the costal cartilages, are strengthened by the radiate sterno-ribular ligaments, ligg. sternocostalia radiata, of which the anterior ones are more powerful than the posterior ones. These ligaments extend radially from the end of the costal
cartilage to the anterior and posterior surfaces of the sternum, forming crosses and interlaces with the ligaments of the same name on the opposite side, as well as with the overlying and underlying ligaments. As a result, a strong fibrous layer is formed covering the sternum - the sternum membrane, membrana sterni.

Fig. 235. Ligaments and joints of the ribs and sternum; front view. (Front cut, the anterior sections of the ribs and sternum are partially removed on the left.)

The bundles of fibers that run from the anterior surface of the 6th to 7th costal cartilages obliquely downwards and medially to the xiphoid process form the xiphoid ligaments, ligg. costoxiphoidea.

In addition, the outer and inner intercostal membranes are located in the intercostal spaces (see Fig. 234, 235).

The external intercostal membrane, membrana intercostalis externa, lies on the anterior surface of the chest in the region of the costal cartilages. The bundles that make it up start from the lower edge of the cartilage and, heading obliquely downwards and anteriorly, end at the upper edge of the underlying cartilage. The internal intercostal membrane, membrana intercostalis interna, is located in the posterior sections of the intercostal spaces. Its bundles start from the upper edge of the rib and, moving obliquely upward and anteriorly, are attached to the lower edge of the overlying rib. In the areas where the membrane is located, there are no intercostal muscles. Both membranes strengthen the intercostal spaces.

The costal cartilages from the 5th to the 9th ribs are connected to each other through dense fibrous tissue and intercartilaginous joints, articulationes interchondrales.

Fig.236. Ligaments and joints of the ribs, vertebrae and sternum; view from above. (Connection of the 5th pair of ribs with the 5th thoracic vertebra and the corresponding segment of the sternum.)

JOINTS OF THE LOWER LIMB

The joints of the lower limb, articulationes membri inferioris, are divided into joints of the lower limb girdle, articulationes cinguli membri inferioris, and joints of the free lower limb, articulationes membri inferioris liberi.

JOINTS OF THE BELT OF THE LOWER LIMB

The bones of the lower limb girdle are connected through two sacroiliac joints and the pubic symphysis of a number of ligaments.

CresTpolyiliac joint

The sacroiliac joint, articulatio sacroiliaca (Fig. 259-261), is a paired joint formed by the iliac bones and the sacrum.

The articular ear-shaped surfaces, facies auriculares, ilium and sacrum are flat, covered with fibrous cartilage. The joint capsule is attached along the edge of the articular surfaces and is tightly stretched. The ligamentous apparatus is represented by strong, highly stretched fibrous bundles located on the anterior and posterior surfaces of the joint. On the anterior surface of the joint are the anterior sacroiliac ligaments, ligg. sacroiliaca anteriora (ventralia). They are short bundles of fibers running from the pelvic surface of the sacrum to the ilium.

There are several ligaments on the back surface of the joint:

1. Interosseous sacroiliac ligaments, ligg. sacroiliaca interossea, lie behind the sacroiliac joint, in the space between the bones that form it, attaching their ends to the iliac and sacral tuberosities.

2. Posterior sacroiliac ligaments, ligg. sacroiliaca posteriora (dorsalia). Separate bundles of these ligaments, starting from the inferior posterior iliac spine, are attached to the lateral sacral crest at the level of 2 - 3 sacral foramina. Others follow from the superior posterior iliac spine downward and somewhat medially, attaching to the posterior surface of the sacrum in the region of the 4th sacral vertebra.

Fig.259. Ligaments and joints of the pelvis; view from above. (Ligaments and joints of the lower limb girdle, lig. et articulationes cinguli membri inferioris. Horizontal and sagittal cuts. Part of the left pelvic bone, left sections of the sacrum and 4-5 lumbar vertebrae were removed.

Fig.260. Ligaments and joints of the pelvis, hip joint, articulatio coxae; back view. (Articular capsule of the left hip joint deleted.)

Fig.261. Ligaments and joints of the pelvis, right side; inside view.
(Sagittal-median cut)

The sacroiliac joint is a low-moving joint.
The pelvic bone, in addition to the sacroiliac joint, is connected to the spinal column through a number of powerful ligaments, which include the following:
1. Sacrotuberous ligament, lig. sacrotuberale (see Fig. 259-261), starts from the medial surface of the ischial tuberosity and, going upward and medially, expands in a fan-shaped manner; attaches to the outer edge of the sacrum and coccyx. Some of the fibers of this ligament pass to bottom part branches of the ischium and, continuing along it, forms the falciform process, porcessus falciformis.
2. Sacrospinous ligament, lig. sacrospinale (see Fig. 259-261), starts from the ischial spine, goes medially and posteriorly and, located in front of the previous ligament, is attached along the edge of the sacrum and partly the coccyx. Both ligaments, together with the greater and lesser sciatic notches, limit two openings: the greater sciatic, foramen ischiadicum majus, and the lesser sciatic, foramen ischiadicum minus. The muscles leaving the pelvis, as well as blood vessels and nerves, pass through these openings.
3. Iliopsoas ligament, lig. iliolumbale (see Fig. 259, 260), starts from the anterior surface of the transverse processes of the 4th and 5th lumbar vertebrae, goes outward and attaches to the posterior parts of the iliac crest and the medial surface of the iliac wing. This ligament strengthens the lumbosacral joint, articulatio lumbosacralis.

Pubic symphysis

The pubic symphysis, symphysis rubica (see Fig. 259, 261), is formed by the articular surfaces of the pubic bones, jacies symphysiales, covered with hyaline cartilage, and the fibrocartilaginous interpubic disc, discus interpubicus, located between them. This disc fuses with the articular surfaces of the pubic bones and has a sagittally located slit-like cavity in its thickness. In women, the disc is slightly shorter than in men, but thicker and has a relatively larger cavity.

The pubic symphysis is strengthened by the following ligaments:
1. Superior pubic ligament, lig. pubicum superius, which is located on the upper edge of the symphysis and is stretched between both pubic tubercles.
2. Arcuate ligament of the pubis, lig. arcuatum pubis, which on the lower edge of the symphysis passes from one pubic bone to another.

The ligaments of the pelvis include the obturator membrane, membrana obturatoria (Fig. 262; see Fig. 260. 261), which consists of bundles of connective tissue fibers, predominantly in a transverse direction. The bundles are attached along the edge of the obturator foramen, running along its entire length, with the exception of the obturator groove. The obturator membrane has a series of small holes. It and the muscles starting from it, together with the obturator groove, limit the obturator canal, canalis obturatorius, through which the vessels and nerves of the same name pass.

JOINTS OF THE FREE LOWER LIMB

Hip joint

The hip joint, articulatio cohae, (Fig. 263-265; see Fig. 260, 262), is formed by the articular surface of the head femur, which is covered with hyaline cartilage throughout, with the exception of the fossa, and the acetabulum of the pelvic bone.
The acetabulum is covered with cartilage only in the area of ​​the semilunar surface, and the rest of the area is made of fatty tissue and covered with a synovial membrane. Above the notch of the acetabulum….

Spinal muscles

The spinal muscles (deep back muscles) are located in three layers.
1. Erector spinae muscle, m. erector spinae (Fig. 296, 297), is located most superficially and is the most powerful and longest muscle of the back; it fills the depression on the sides along the entire length of the back from the spinous processes to the corners of the ribs (see Fig. 43). The muscle begins from the posterior part of the iliac crest, the dorsal surface of the sacrum, the spinous processes of the lower lumbar vertebrae and partly from the superficial layer of the thoracolumbar fascia. Heading upward, the muscle is divided in the lumbar region into three parts: the iliac muscle is located laterally, the medial spinalis muscle, and between them is the longissimus muscle.
A) iliocostal muscles a, m. iliocostalis (see Fig. 295-297), with numerous muscle and tendon teeth, is attached to the corners of all ribs and transverse processes of the lower cervical vertebrae. The following muscles are topographically distinguished:
P iliocostal muscle lower back, m. iliocostalis lumborum, originates from the posterior part of the lateral sacral crest and the thoracolumbar fascia and, moving sideways and upward, forms 8 - 9 teeth, which are attached to the corners of the eight to nine lower ribs by thin narrow tendons;
iliocostal muscle of the chest, m. iliocostalis thoracis, starting near the corners of the lower five to six ribs, follows somewhat obliquely upward and outward and is attached by thin narrow tendons to the corners of the upper five to seven ribs;
iliocostal neck muscle , m. iliocostalis cervicis, starts from the corners of the five to seven upper ribs, also goes obliquely upward and laterally and with three teeth is attached to the posterior tubercles of the transverse processes of the 4th, 5th and 7th cervical vertebrae.

Fig.296. Muscles of the back, neck and suboccipital muscles.
(Deep dorsal muscles long: second superficial layer.)

Innervation me: rr. dorsales nn. spinales (C3-C5; Th1-L1).
b) longissimus muscle, m. longissimus (see Fig. 295-297), is located medial to the iliocostal muscle, extending from the sacrum to the base of the skull. Topographically it differs:
longissimus thoracis muscle, m. longissimus thoracis, which starts from the posterior surface of the sacrum, the transverse processes of the lumbar and lower six to seven thoracic vertebrae, etc. following upward, it is attached to the corners of the ten lower ribs and to the posterior sections of the transverse processes of all thoracic vertebrae;
longissimus colli muscle, m. longissimus cervicis, originates from the transverse processes of four to five upper thoracic and lower cervical vertebrae and. going upward, it attaches to the transverse processes of the vertebrae from the axial to the 5th cervical;
longest head muscle, m. longissimus capitis. starts from the transverse processes of the three upper thoracic and three to four lower cervical vertebrae, goes upward and attaches to the posterior edge of the mastoid process.

Innervation: rr. dorsales nn. spinales (C1 - S2)
c) Spinalis muscle, m. spinalis (see Fig. 295-297), is located along the spinous processes and is topographically divided into a number of muscles:

Fig.297. Places of origin and insertion of the back muscles (diagram)

O pectoralis muscle, m. spinalis thoracis. starts from the spinous processes of two or three upper lumbar and two or three lower thoracic vertebrae and, going upward, attaches to the spinous processes of 8 - 2 thoracic vertebrae;
spinalis muscle of the neck, m. spinalis cervicis, originates from the spinous processes of the two upper thoracic and two lower cervical vertebrae and, following upward, ends on the spinous processes of the upper cervical vertebrae - from 4 to 2;
spinalis capitis muscle, m. spinalis capitis, a poorly developed section of the spinalis muscle, sometimes forms part of the m. semispinalis capitis or absent. It starts from the spinous processes of the upper thoracic and lower cervical vertebrae, goes upward and attaches near the external occipital protrusion.
Function: entire erector spinae muscle, m. erector spinae, with bilateral contraction, is a powerful extensor of the spinal column, holding the torso in an upright position. With unilateral contraction, the spinal column tilts in the appropriate direction. The upper muscle bundles pull the head in their direction. With part of its tufts (m. iliocostalis thoracis) it lowers the ribs.
Innervation:nn. spinales (C1 – S2).
2. Transverse spinalis muscle, m. transversospinalis (Fig. 298-300), covered by m. erector spinae and fills the depression between the spinous and transverse processes along the entire spinal column. Relatively short muscle bundles have an oblique direction, spreading from the transverse processes of the underlying vertebrae to the spinous processes.

Fig.298. back muscles, posterior region neck and suboccipital muscles.
(Deep back muscles: first and second layers.)

overlying ones. According to the length of the muscle bundles, i.e., according to the number of vertebrae through which the muscle bundles are thrown, three parts are distinguished in the transverse spinalis muscle:
A) semispinalis muscle y, the bundles of which are thrown across 5-6 vertebrae or more; it is located more superficially;
b) multifidus muscles, the bundles of which are thrown across 2-4 vertebrae; They
covered by the semispinalis muscle;

V) rotator cuff muscles, the bundles of which occupy the deepest position and are attached to the spinous process of the overlying vertebra or are transferred to the next overlying vertebra.

A) Semispinalis muscle, m. semispinalis (see Fig. 298-300), topographically divided into the following parts:
semispinalis pectoralis muscle, m. semispinalis thoracis, located between the transverse processes of the six lower and spinous processes of the seven upper thoracic vertebrae; in this case, each bundle is thrown over five to seven vertebrae;
semispinalis neck muscle,m. semispinalis cervicis, lies between the transverse processes of the upper thoracic and spinous processes of the six lower cervical vertebrae. Its bundles extend across two to five vertebrae;

semispinalis capitis muscle s, m. semispinalis capitis, lies between the transverse processes of the five upper thoracic vertebrae and 3-4 lower cervical vertebrae on one side and the nuchal platform of the occipital bone on the other. This muscle has lateral and medial parts; the medial part in the muscle belly is interrupted by a tendon bridge.

Function: when all the bundles contract, the muscle extends the upper parts of the spinal column and pulls the head back or holds it in a tilted position; with unilateral contraction, slight rotation occurs.
Innervation: rr. dorsales nn. spinales (C2 - C5; Th1 - Th12)
b) Multifidus muscles,mm. multifidi (Fig. 301; see Fig. 298-300), covered by the semispinalis, and in the lumbar region - by the lumbar part longissimus muscle. Muscle bundles are located throughout the spinal column between the transverse and spinous processes of the vertebrae (up to the 2nd cervical), spreading across 2, 3 or 4 vertebrae. Muscle bundles begin from the posterior surface of the sacrum, the posterior segment of the iliac crest, the mastoid processes of the lumbar, the transverse processes of the thoracic and articular processes of the four lower cervical vertebrae; end on the spinous processes of all vertebrae except the atlas.

Fig.299. Places of origin and insertion of the trunk muscles (diagram)

(Deep back muscles: second deep layer.)

Innervation:mm. dorsales nn. spinales (C2 - S1)

V) Rotator muscles,mm. rotatores (see Fig. 299-301), are the deepest part of the transverse spinous muscles and are topographically divided into cervical rotators, mm. rotatores cervicis, chest rotators, mm. rotatores thoracis, and lumbar rotators, mm. rotatores lumborum.

They begin from the transverse processes of all vertebrae, except the atlas, and from the mastoid processes of the lumbar vertebrae. Throwing over one vertebra, they attach to the spinous processes of the overlying vertebrae, to adjacent segments of their arches and to the base of the arches of neighboring vertebrae.

Fig. 300. Back muscles and suboccipital muscles.
(Deep back muscles: second and third layers.)

Function: The transverse spinalis muscle, when contracted bilaterally, extends the spinal column, and when contracted unilaterally, it rotates it in the direction opposite to the contracting muscle.
Innervation: nn. spinales (C2–L5)
3. Interspinous muscles,mm. interspinales (see Fig. 297, 298, 300, 301) - short paired muscle bundles stretching between the spinous processes of two adjacent vertebrae. The interspinous muscles are located along the entire spinal column, with the exception of the sacrum. There are interspinous muscles of the neck, mm. interspinales cervicis, interspinous muscles of the chest, mm. interspinales thoracis (often absent), interspinous muscles of the lumbar region, mm. interspinales lumborum.
Function: straighten the spinal column and keep it in an upright position.
Innervation: rr. dorsales nn. spinales (C3 – L5)
4. Intertransverse muscles,mm. intertransversarii (see Fig. 298-301), short muscles, stretch between the transverse processes of two adjacent vertebrae. There are posterior and anterior intertransverse muscles of the neck, mm. intertransversarii posteriors et anteriores cervicis, intertransverse muscles of the chest, mm. intertransversarii thoracis; lateral and medial intertransverse lumbar muscles, mm. intertransversarii laterales et mediales lumborum.
Function: hold the spinal column, and with unilateral contraction, tilt it to the side.
Innervation: rr. dorsales nn. spinales (C1 – C6; L1-L4)
Blood supply: aa delivers blood to all deep muscles of the back. occipitalis, cervicalis profundus, intercostales posteriores; ah. lumbales.

Fig. 301. Places of origin and insertion of the back muscles (diagram). (Deep back muscles: second deep layer. Short muscles back of the neck.)

Fascia of the back

There are three fascia of the back.

1. Superficial fascia of the back- a thin connective tissue layer, part of the common subcutaneous fascia, covers superficial muscles backs.

2. Nuchal fascia, fascia nuchae, is located in the back of the neck, between the superficial and deep layers of muscles. Medially it fuses with the nuchal ligament (see Fig. 295), laterally it passes into the superficial layer of the fascia of the neck, and at the top it is attached to the superior nuchal line.

3. Lumbothoracic fascia, fascia thoracolumbalis (see Fig. 294, 295, 298, 300), forms a dense fibrous sheath in which the deep muscles of the back lie. This fascia consists of two layers - deep (anterior) and superficial (posterior). The deep layer of the thoracolumbar fascia stretches between the transverse processes of the lumbar vertebrae, the iliac crest and the 12th rib. It is present only in the lumbar region and lies between quadratus muscle lower back, m. quadratus lumborum, and the erector spinae muscle, m. erector spinae.

The superficial layer of the thoracolumbar fascia is attached below to the iliac crests, laterally reaches the corners of the ribs and medially is attached to the spinous processes of all vertebrae, except the cervical ones. It reaches its greatest thickness in the lumbar region, and in the upper sections it becomes significantly thinner. Laterally, along the lateral edge of m. erectoris spinae, the superficial leaf is fused with the deep one. In this way, a fibrous vagina is formed, in which the lumbar part of the m lies. erectoris spinae; the upper sections of this muscle are located in the osteofibrous sheath of the back.

The vertebra (Fig. 8) has a body and an arch that closes the vertebral foramen. There are 7 processes on the arch: 2 upper articular, 2 lower articular, 2 transverse and spinous. At the base of the arch are the superior and inferior vertebral notches. The notches of two adjacent vertebrae form the intervertebral foramen.

Cervical vertebrae. Distinctive feature cervical vertebrae is the presence of holes in the transverse processes. The bodies of the cervical vertebrae are small, oval, elongated in the transverse direction. The vertebral foramen is large and triangular in shape. The transverse processes of the cervical vertebrae consist of two parts: the transverse process itself and the costal process, which is a rudiment of the rib. In the VI cervical vertebra, the costal process is most developed; the carotid artery is closely adjacent to it. If necessary, it can be pressed against the tubercle of the costal process, which is called the carotid tubercle (tuberculum caroticum). The spinous process of the VII cervical vertebra is longer than that of the other cervical vertebrae. It protrudes noticeably and can be felt through the skin; hence the entire vertebra received the name protruding (vertebra prominens; see Fig. 7, B).

The first cervical vertebra - the atlas - has no body. Its two lateral masses are connected by anterior and posterior arches. On the lateral masses, on top are the upper articular surfaces (for connection with the skull), and below are the lower articular surfaces (for connection with the II cervical vertebra).

The second cervical vertebra - the axial - differs from other vertebrae in that its body has a massive process - a tooth. By its origin, the tooth is part of the body of the first cervical vertebra. The tooth serves as an axis around which the head rotates along with the atlas.

Thoracic vertebrae. A characteristic feature of the thoracic vertebra is the presence of upper and lower costal fossae on the lateral surfaces of the body. The head of the rib joins them. There is also a costal fossa on the transverse process (for connection with the tubercle of the rib). The bodies of the thoracic vertebrae are larger than those of the cervical vertebrae, and the vertebral foramen is round.

Lumbar vertebrae. The body of the lumbar vertebra is very massive and bean-shaped. The vertebral foramen is relatively small, oval. The spinous processes are directed horizontally, the gaps between them are large.

Sacrum (os sacrum; Fig. 9, a and b). In children and adolescents, the sacral vertebrae exist separately. At the age of 17 - 25 years, they grow together and form one bone - the sacrum. It has the shape of a triangle: the base faces up, the top faces down. The anterior concave pelvic surface (fades pelvica) takes part in the formation of the pelvic cavity. It shows traces of fusion of the bodies of the sacral vertebrae - transverse lines. At the ends of each of the four lines there is a pair of anterior sacral foramina. To the side of the pelvic openings lie the lateral parts - these are fused transverse processes and rudiments of the ribs of the sacral vertebrae.

The dorsal surface (fades dorsalis) is convex and uneven.

In its center, the median sacral ridge runs vertically - a trace of the fusion of the spinous processes of the sacral vertebrae. More lateral is the paired intermediate sacral ridge, formed from the fusion of the articular processes of the sacral vertebrae. On top, this ridge ends with the usual upper articular processes of the 1st sacral vertebra, and below, with modified lower articular processes of the 5th sacral vertebra, called the sacral horns (cornua sacralia). The latter limit the exit of the sacral canal - the sacral fissure (hiatus sacralis). 4 pairs of posterior sacral foramina are clearly visible. Lateral to them is the paired lateral sacral ridge, which is the fused transverse processes of the sacral vertebrae. In the upper parts of the lateral surface of the lateral parts of the sacrum there is an articular auricular surface for articulation with the pelvic bones. The sacral canal runs inside the sacrum.

From the base, the sacrum articulates with the V lumbar vertebra, and from the apex, with the coccyx.

Coccyx (os coccygis; Fig. 9, c). The coccyx is a rudiment of the caudal skeleton of animals. In humans, it ossifies late and consists of 3-5 underdeveloped vertebrae. The first (I) coccygeal vertebra from above has modified superior articular processes called coccygeal horns. They connect to the sacral horns. On the body of the first coccygeal vertebra, outgrowths extend to the sides - rudiments of transverse processes. The remaining coccygeal vertebrae have the shape of oval bone bodies.

Humerus - long bone. It distinguishes between a body and two epiphyses - the upper proximal and lower distal. The body of the humerus, corpus humeri, is rounded in the upper part and triangular in the lower part.

IN lower section the bodies are distinguished by the posterior surface, facies posterior, which is limited along the periphery by the lateral and medial edges, margo lateralis et margo medialis; the medial anterior surface, facies anterior medialis, and the lateral anterior surface, facies anterior lateralis, separated by an inconspicuous ridge.

On the medial anterior surface body of humerus, slightly below the middle of the body length, there is a nutrient opening, foramen nutricium, which leads into the distally directed nutrient canal, canalis nutricius.

Above the nutrient opening on the lateral anterior surface of the body there is a deltoid tuberosity, tuberositas deltoidea, - the place of attachment, m. deltoideus

On the posterior surface of the body of the humerus, behind the deltoid tuberosity, there is a groove of the radial nerve, sulcus n. radialis. It has a spiral motion and is directed from top to bottom and from inside to outside.

Upper, or proximal, epiphysis, extremitas superior, s. epiphysis proximalis. thickened and bears a hemispherical humeral head, caput humeri, the surface of which faces inwards, upwards and somewhat posteriorly. The periphery of the head is delimited from the rest of the bone by a shallow ring-shaped narrowing - the anatomical neck, collum anatomicum. Below the anatomical neck, on the anterior outer surface of the bone, there are two tubercles: on the outside - the large tubercle, tuberculum majus, and on the inside and slightly in front - the small tubercle, tuberculum minus.

A ridge of the same name stretches down from each tubercle; crest of the greater tubercle, crista tuberculi majoris, and crest of the lesser tubercle, crista tuberculi minoris. Heading down, the ridges reach the upper parts of the body and, together with the tubercles, limit a well-defined intertubercular groove, sulcus intertubercularis, in which the tendon of the long head of the biceps brachii muscle, tendo capitis longi m, lies. bicepitis brachii.
Below the tubercles, at the border of the upper end and the body of the humerus, there is a small narrowing - the surgical neck, collum chirurgicum, which corresponds to the area of ​​the epiphysis.

On the anterior surface of the distal epiphysis of the humerus above the trochlea there is a coronoid fossa, fossa coronoidea, and above the head of the condyle of the humerus there is a radial fossa, fossa radialis, on the posterior surface there is an olecranon fossa, fossa olecrani.

Peripheral parts of the lower end humerus end with the lateral and medial epicondyles, epicondylus lateralis et medialis, from which the muscles of the forearm begin.