Special anatomy shoulder joint provides high hand mobility in all planes, including 360-degree circular movements. But the price for this was the vulnerability and instability of the joint. Knowledge of the anatomy and structural features will help to understand the cause of diseases that affect the shoulder joint.

But before we start detailed review of all the elements that make up the formation, two concepts should be differentiated: the shoulder and the shoulder joint, which many confuse.

Shoulder is top part arms from the armpit to the elbow, and the shoulder joint is the structure by which the arm is connected to the torso.

Structural features

If we consider it as a complex conglomerate, the shoulder joint is formed by bones, cartilage, joint capsule, bursae, muscles and ligaments. In its structure, it is a simple, complex spherical joint consisting of 2 bones. The components that form it have different structures and functions, but are in strict interaction designed to protect the joint from injury and ensure its mobility.

Shoulder joint components:

• spatula
• brachial bone
• labrum
• joint capsule
• bursae
• muscles, including the rotator cuff
• ligaments

The shoulder joint is formed by the scapula and humerus, enclosed in a joint capsule.

The rounded head of the humerus is in contact with the fairly flat articular bed of the scapula. In this case, the scapula remains practically motionless and the movement of the hand occurs due to the displacement of the head relative to the articular bed. Moreover, the diameter of the head is 3 times larger than the diameter of the bed.

This discrepancy between shape and size provides a wide range of movements, and the stability of the articulation is achieved through the muscular corset and ligamentous apparatus. The strength of the articulation is also given by the articular lip located in the scapular cavity - cartilage, the curved edges of which extend beyond the bed and cover the head of the humerus, and the elastic rotator cuff surrounding it.

Ligamentous apparatus

The shoulder joint is surrounded by a dense joint capsule (capsule). The fibrous membrane of the capsule has varying thicknesses and is attached to the scapula and humerus, forming a spacious sac. It is loosely stretched, which makes it possible to freely move and rotate the hand.

The inside of the bursa is lined with a synovial membrane, the secretion of which is synovial fluid, which nourishes the articular cartilages and ensures the absence of friction when they slide. On the outside, the joint capsule is strengthened by ligaments and muscles.

The ligamentous apparatus performs a fixing function, preventing displacement of the head of the humerus. Ligaments are formed by strong, poorly extensible tissues and are attached to bones. Poor elasticity causes damage and rupture. Another factor in the development of pathologies is an insufficient level of blood supply, which is the cause of the development of degenerative processes of the ligamentous apparatus.

Shoulder joint ligaments:

1. coracobrachial
2. top
3. average
4. lower

Human anatomy is a complex, interconnected and fully thought-out mechanism. Since the shoulder joint is surrounded by a complex ligamentous apparatus, for the sliding of the latter, mucous synovial bursae (bursae) are provided in the surrounding tissues, communicating with the joint cavity. They contain synovial fluid, ensure smooth operation of the joint and protect the capsule from stretching. Their number, shape and size are individual for each person.

Muscular frame

The muscles of the shoulder joint are represented by both large structures and small ones, due to which the rotator cuff is formed. Together they form a strong and elastic frame around the joint.

Muscles surrounding the shoulder joint:

• Deltoid. It is located on top and outside the joint, and is attached to three bones: the humerus, scapula and clavicle. Although the muscle is not directly connected to the joint capsule, it reliably protects its structures on 3 sides.
• Biceps (biceps). It is attached to the scapula and humerus and covers the joint from the front.
• Triceps (triceps) and coracoid. Protects the joint from the inside.

The rotator cuff of the shoulder joint allows a wide range of motion and stabilizes the head of the humerus, holding it in the socket.

It is formed by 4 muscles:

1. subscapularis
2. infraspinatus
3. supraspinatus
4. small round

The rotator cuff is located between the head of the humerus and the acromin, the process of the scapula. If the space between them is due to for various reasons narrows, the cuff is pinched, leading to a collision of the head and acromion, and is accompanied by severe pain.

Doctors called this condition “impingement syndrome.” With impingement syndrome, injury to the rotator cuff occurs, leading to its damage and rupture.

Blood supply

The blood supply to the structure is carried out using an extensive network of arteries, through which nutrients and oxygen enter the joint tissues. Veins are responsible for removing waste products. In addition to the main blood flow, there are two auxiliary vascular circles: the scapular and the acromial deltoid. The risk of rupture of large arteries passing near the joint significantly increases the risk of injury.

Elements of blood supply

• suprascapular
• front
• back
• thoracoacromial
• subscapularis

• humeral
• axillary

Innervation

Any damage or pathological processes in the human body are accompanied by pain. Pain can signal the presence of problems or perform security functions.

In the case of joints, soreness forcibly “deactivates” the diseased joint, preventing its mobility in order to allow injured or inflamed structures to recover.

Shoulder nerves:

• axillary
• suprascapular
• chest
• ray
• subscapular
• axle

Development

When a child is born, the shoulder joint is not fully formed, its bones are separated. After the birth of a child, the formation and development of shoulder structures continues, which takes about three years. During the first year of life, the cartilaginous plate grows, the articular cavity is formed, the capsule contracts and thickens, and the ligaments surrounding it strengthen and grow. As a result, the joint is strengthened and fixed, reducing the risk of injury.

Over the next two years, the articulation segments increase in size and take on their final shape. The humerus is the least susceptible to metamorphosis, since even before birth the head has a rounded shape and is almost completely formed.

Shoulder instability

The bones of the shoulder joint form a movable joint, the stability of which is provided by muscles and ligaments.

This structure allows for a large range of movements, but at the same time makes the joint prone to dislocations, sprains and ligament tears.

Also, people often encounter a diagnosis such as instability of the articulation, which is made when, when moving the arm, the head of the humerus extends beyond the articular bed. In these cases we're talking about not about an injury, the consequence of which is a dislocation, but about the functional inability of the head to remain in the desired position.

There are several types of dislocations depending on the displacement of the head:

1. front
2. rear
3. lower

The structure of the human shoulder joint is such that it is covered from behind by the scapula, and from the side and above by the deltoid muscle. The frontal and internal parts remain insufficiently protected, which causes the predominance of anterior dislocation.

Functions of the shoulder joint

High mobility of the joint allows for all movements available in 3 planes. Human hands can reach any point of the body, carry heavy loads and perform delicate work that requires high precision.

Movement options:

• lead
• casting
• rotation
• circular
• bending
• extension

It is possible to perform all of the listed movements in full only with the simultaneous and coordinated work of all elements shoulder girdle, especially the clavicle and acromioclavicular joint. With the participation of one shoulder joint, the arms can only be raised to shoulder level.

Knowledge of the anatomy, structural features and functioning of the shoulder joint will help to understand the mechanism of injury, inflammatory processes and degenerative pathologies. Health of all joints in human body directly depends on lifestyle.

Excess weight and lack physical activity cause damage to them and are risk factors for the development of degenerative processes. Careful and attentive attitude towards your body will allow all its constituent elements to work for a long time and flawlessly.

Laboratory lesson

"Muscles upper limb»

Muscles, producingmovementtop beltlimbs

Schematically, the movements of the upper limb girdle (scapula and clavicle) are divided into:

Movement forward and backward with abduction of the scapula from the spinal column and adduction to it.

Raising and lowering the scapula and clavicle.

Movement of the scapula around the sagittal axis with the lower angle to the medial and lateral sides.

Circular movement of the lateral end of the clavicle and at the same time the scapula.

These movements involve six functional muscle groups.

Movementforward

The forward movement of the upper limb girdle is produced by muscles that cross the vertical axis of the sternoclavicular joint and are located in front of it. These include:

pectoralis major, acting on the girdle of the upper limb through humerus;

pectoralis minor;

anterior serratus.

Movementback

They are carried out by the muscles that cross the vertical axis of the sternoclavicular joint and lie behind it. This muscle group includes:

trapezius muscle;

rhomboid muscle, major and minor;

latissimus dorsi muscle.

Movementup

Raising the belt of the upper limb is performed by the following muscles:

1) upper beams trapezius muscle which pulls up the lateral end of the clavicle and the acromion of the scapula;

levator scapulae muscle;

rhomboid muscles, during the decomposition of the resultant of which there is a certain component directed upward;

the sternocleidomastoid muscle, which, attaching one of its heads to the collarbone, pulls it, and, consequently, the scapula upward.

Movementdown

Lowering is facilitated by muscles running from bottom to top, from chest or the spinal column to the bones of the upper limb girdle:

small pectoral muscle;

subclavius ​​muscle;

lower bundles of trapezius muscle;

inferior teeth of the serratus anterior muscle.

In addition, the muscles that go from the torso to the shoulder, namely the pectoralis major muscle and the latissimus dorsi muscle, help lowering, mainly through their lower parts.

Rotationshoulder blades(movementlowerangleinsideAndoutward)

Rotation of the scapula inward, with the lower angle to the spinal column, is produced by a pair of forces formed by:

pectoralis minor muscle

the lower part of the rhomboid major muscle.

Rotation of the scapula outward, with the lower angle from the spinal column to the lateral side, occurs as a result of the action of a pair of forces generated by the upper and bottom parts trapezius muscle.

This movement is supported by:

serratus anterior muscle with its lower and middle teeth;

teres major muscle with a fixed free upper limb.

Circularmovement

The circular movement of the upper limb girdle occurs as a result of alternate contraction of all its muscles.

Muscles, producingmovement inshoulderjoint

In the shoulder joint, movements are possible around three mutually perpendicular axes:

abduction and adduction around the anteroposterior axis;

flexion and extension around the transverse axis;

pronation and supination around the vertical axis;

circular motion (circumduction).

These movements are provided by six functional muscle groups.

Leadshoulder

The shoulder abductor muscles cross the sagittal axis of rotation in the shoulder joint and are located lateral to it. The humerus is abducted by the following muscles:

deltoid and

supraspinatus.

Bringingshoulder

There are no special muscles that would cross the sagittal axis of the shoulder joint and are located medial to it, therefore, adduction of the shoulder according to the parallelogram of forces rule is carried out with the simultaneous contraction of muscles located in front (the pectoralis major muscle) and behind the shoulder joint (the latissimus and teres major). These muscles help:

infraspinatus;

small round;

subscapular;

long head of the triceps brachii muscle;

coracobrachial muscles.

Flexionshoulder

The shoulder flexor muscles cross the frontal (transverse) axis of the shoulder joint and are located in front of it.

Shoulder flexion (moving it forward) is produced by the following muscles:

pectoralis major;

coracobrachial;

biceps brachii muscle.

Extensionshoulder

The muscles that extend the shoulder (move it backward), like the shoulder flexors, cross the frontal axis of the shoulder joint, but are located behind it. Shoulder extension is produced by the following muscles:

its deltoid posterior part;

latissimus dorsi muscle;

infraspinatus;

small round;

large round;

long head of the triceps brachii muscle.

Pronationshoulder

Pronation of the shoulder, i.e. turning inward, produced by muscles; which cross the vertical axis of the shoulder joint, attaching in front of it. These include:

subscapular;

pectoralis major;

deltoid, its anterior part;

latissimus dorsi muscle;

large round;

coracobrachial.

Supinationshoulder

Supination, i.e. turning the shoulder outward is produced by muscles that, like the pronators, cross the vertical axis of the shoulder joint, but are located behind it:

rear end deltoid muscle

small teres muscle

infraspinatus muscle

biceps brachii

Flexionforearms

Flexion of the forearm is performed by muscles that cross the transverse axis of the elbow joint and are located in front of it. These muscles include:

1) biceps brachii;

2) shoulder;

3) brachioradialis;

4) pronator teres.

Brachial muscle - when flexing the forearm, the muscle clearly protrudes and can be easily felt above the skin. This muscle is not only a flexor of the forearm, but also a supinator (if the forearm is pronated), and if it is supinated, then it is a pronator.

Pronator teres – participates in two movements of the forearm: flexion and pronation.

Circularmovementshoulder

With the alternate action of all the muscles located in the circumference of the shoulder joint, a circular movement occurs in it. Examining these muscles, it is easy to notice that they lie unevenly, namely: there are no muscles inside and below this joint; instead, there is a depression called axillary fossa.

Axillary fossa its shape is somewhat reminiscent of a pyramid, with its base facing downward and outward, and its apex upward and inward. It has three walls, the front of which is formed by the pectoralis major and minor muscles, the back by the subscapularis, teres major and latissimus dorsi muscles, and the inner by the serratus anterior muscle. In the depression between the anterior and posterior walls lie the coracobrachialis muscle and the short head of the biceps brachii muscle.

Muscles, producingmovement inelbowjoint

In the elbow joint with a fixed shoulder, the following are possible:

flexion and extension of the forearm;

pronation and supination of the forearm.

Extensionforearms

Extension of the forearm is performed by muscles crossing the transverse axis elbow joint and those behind her. There are two of these muscles:

triceps brachii and

ulna.

Pronationforearms

Pronation of the forearm is produced by the following muscles:

pronator teres

pronator quadratus

brachioradialis muscle.

Supinationforearms

The supinators of the forearm are:

biceps brachii

supinator muscle

brachioradialis muscle.

Muscles, producingmovementVwrist jointAndjointsbrushes

Flexionbrushes

Flexion of the hand involves muscles that cross the transverse axis and are located in front of it on the anterior surface of the forearm and hand. These include:

1) long palmar;

flexor carpi radialis;

flexor carpi ulnaris;

flexor digitorum superficialis;

flexor digitorum profundus;

flexor longus thumb.

Extensionbrushes

Extension of the hand is produced by muscles that cross the transverse axis of the wrist joint and are located behind it on the back surface of the forearm. These muscles are multi-articular. They produce simultaneous extension in all joints around which they pass. These muscles include:

extensor carpi radialis longus;

extensor carpi radialis brevis;

extensor carpi ulnaris;

extensor digitorum;

extensor of the little finger;

extensor index finger;

extensor pollicis longus.

Bringingbrushes

There are no muscles located on the medial surface of the ulna and extending to the hand strictly along the medial surface of the wrist joint. The adduction of the hand occurs according to the rule of the parallelogram of forces with simultaneous contraction:

flexor carpi ulnaris

extensor carpi ulnaris

Leadbrushes

The following muscles are involved in wrist abduction:

flexor carpi radialis

extensor carpi radialis longus

extensor carpi radialis brevis

abductor pollicis longus muscle

extensor pollicis longus.

Laboratory lesson

"Muscles of the upper limb"

Muscles producing movements of the upper limb belt

Schematically, the movements of the upper limb girdle (scapula and clavicle) are divided into:

1.Movement forward and backward with abduction of the scapula from the spinal column and adduction to it.

2. Raising and lowering the scapula and clavicle.

3.Movement of the scapula around the sagittal axis with the lower angle to the medial and lateral sides.

4. Circular movement of the lateral end of the clavicle and at the same time the scapula.

These movements involve six functional muscle groups.

Forward movement

The forward movement of the upper limb girdle is produced by the muscles that cross the vertical axis of the sternoclavicular joint and are located in front of it. These include:

1) pectoralis major, acting on the girdle of the upper limb through the humerus;

2) pectoralis minor;

3) anterior dentate.

Moving backwards

They are carried out by the muscles that cross the vertical axis of the sternoclavicular joint and lie behind it. This muscle group includes:

1) trapezius muscle;

2) rhomboid muscle, major and minor;

3) latissimus dorsi muscle.

Upward movement

Raising the belt of the upper limb is performed by the following muscles:

1) the upper bundles of the trapezius muscle, which pulls up the lateral end of the clavicle and the acromion of the scapula;

4) the levator scapulae muscle;

5) rhomboid muscles, during the expansion of the resultant of which there is some component directed upward;

6) the sternocleidomastoid muscle, which, attaching one of its heads to the collarbone, pulls it, and, consequently, the scapula upward.

Moving Down

Lowering is facilitated by muscles that go from bottom to top, from the chest or spinal column to the bones of the upper limb girdle:

1) pectoralis minor muscle;

2) subclavian muscle;

3) lower bundles of the trapezius muscle;

4) lower teeth of the serratus anterior muscle.

In addition, the muscles that go from the torso to the shoulder, namely the pectoralis major muscle and the latissimus dorsi muscle, help lowering, mainly through their lower parts.

Rotation of the scapula (movement of the lower angle inward and outward)

Rotation of the scapula inward, with the lower angle to the spinal column, is produced by a pair of forces formed by:

1) pectoralis minor muscle

2) bottom rhomboid major muscle.

Rotation of the scapula outward, with the lower angle from the spinal column to the lateral side, occurs as a result of the action of a pair of forces generated by the upper and lower parts of the trapezius muscle.

This movement is supported by:

1) serratus anterior muscle with its lower and middle teeth;

2) teres major muscle with a fixed free upper limb.

Roundabout Circulation

The circular movement of the upper limb girdle occurs as a result of alternate contraction of all its muscles.

Muscles that produce movements in the shoulder joint

In the shoulder joint, movements around three mutually perpendicular axes are possible:

1) abduction and adduction around the anteroposterior axis;

2) flexion and extension around the transverse axis;

3) pronation and supination around the vertical axis;

4) Roundabout Circulation(circumduction).

These movements are provided by six functional muscle groups.

Shoulder abduction

The shoulder abductor muscles cross the sagittal axis of rotation in the shoulder joint and are located lateral to it. The humerus is abducted by the following muscles:

1)deltoid and

2) supraspinatus.

Shoulder adduction

There are no special muscles that would cross the sagittal axis of the shoulder joint and are located medial to it, therefore, adduction of the shoulder according to the parallelogram of forces rule is carried out with the simultaneous contraction of muscles located in front (the pectoralis major muscle) and behind the shoulder joint (the latissimus and teres major). These muscles help:

1) infraspinatus;

2) small round;

3) subscapular;

4)long head triceps brachii;

5) coracobrachial muscles.

Shoulder flexion

The shoulder flexor muscles cross the frontal (transverse) axis of the shoulder joint and are located in front of it.

Shoulder flexion (moving it forward) is produced by the following muscles:

1) deltoid, its anterior part;

2) pectoralis major;

3) coracobrachial;

4) biceps brachii muscle.

Shoulder extension

The muscles that extend the shoulder (move it backward), like the shoulder flexors, cross the frontal axis of the shoulder joint, but are located behind it. Shoulder extension is produced by the following muscles:

1) its deltoid posterior part;

2) latissimus dorsi muscle;

3) infraspinatus;

4) small round;

5) large round;

6) long head of the triceps brachii muscle.

Shoulder pronation

Pronation of the shoulder, i.e. turning inward, produced by muscles; which cross the vertical axis of the shoulder joint, attaching in front of it. These include:

1) subscapular;

2) pectoralis major;

3) deltoid, its anterior part;

4) latissimus dorsi muscle;

5) large round;

6) coracobrachial.

Shoulder supination

Supination, i.e. turning the shoulder outward is produced by muscles that, like the pronators, cross the vertical axis of the shoulder joint, but are located behind it:

1) back of the deltoid muscle

2) teres minor muscle

3) infraspinatus muscle

4) biceps brachii muscle

There are no special muscles that would cross the sagittal axis of the shoulder joint and are located medial to it, therefore, adduction of the shoulder according to the parallelogram of forces rule is carried out with the simultaneous contraction of muscles located in front (the pectoralis major muscle) and behind the shoulder joint (the latissimus and teres major). These muscles help:

1) infraspinatus;

2) small round;

3) subscapular;

4) long head of the triceps brachii muscle (see page 160);

5) coracobrachialis muscle (see page 156).

Cavity muscle(see Fig. 38) is located in the infraspinatus fossa of the scapula, from which it begins. In addition, the origin of this muscle is the infraspinatus fascia. Muscle attached to the greater tubercle of the humerus, being covered partly by the trapezius and partly by the deltoid muscle.

The function of the infraspinatus muscle is to adduct, supine and extend the shoulder at the shoulder joint. Since this muscle is attached to the capsule of the shoulder joint, when the shoulder is supinated, it simultaneously retracts the capsule, protecting it from pinching.

Teres minor muscle(see Fig. 38) is located below the infraspinatus muscle. She begins from the shoulder blade, and attached to the greater tubercle of the humerus and promotes adduction, supination and extension of this bone.

Teres major muscle(see Fig. 38) begins from the lower angle of the scapula and attached to the crest of the lesser tubercle of the humerus, often with one tendon with latissimus muscle backs. When contracting, the teres major muscle acts as a rounded eminence when the pronated shoulder is adducted. The function of the muscle is to adduct, pronate and extend the humerus. Subscapularis muscle located on the anterior surface of the scapula, filling the subscapular fossa, from which begins. When attached muscle to the lesser tubercle of the humerus. Contracting together with the previous muscles, it produces shoulder adduction; acting in isolation, it is its pronator. Since this muscle is multi-pinnate, it has significant

47. Age and gender characteristics of muscle development, the influence of work activity and physical education and sports on muscle development.

48. Formations of the auxiliary apparatus of muscles (fascia, fascial ligaments, fibrous and osteofibrous canals, synovial sheaths, mucous bursae, sesamoid bones, pulleys) and their functions.

49. Abdominal muscles: topography, origin, attachment and functions.

50. Muscles of inspiration. Muscles of exhalation.

52. Neck muscles: topography, origin, attachment and functions.

53. Muscles that flex the spine.

54. Muscles that extend the spine.

55. Muscles of the anterior surface of the forearm: origin, attachment and functions.

56. Muscles of the posterior surface of the forearm: origin, attachment and functions.

57. Muscles that produce forward and backward movements of the upper limb girdle.

58. Muscles that produce up and down movements of the upper limb girdle.

59. Muscles that flex and extend the shoulder.

60. Muscles that abduct and adduct the shoulder.

61. Muscles that supinate and pronate the shoulder.

62. Muscles that flex (main) and extend the forearm.

63. Muscles that supinate and pronate the forearm.

64. Muscles that flex and extend the hand and fingers.

65. Muscles that abduct and adduct the hand.

66. Thigh muscles: topography and functions.

67. Muscles that flex and extend the hip.

68. Muscles that abduct and adduct the thigh.

69. Muscles that supinate and pronate the thigh.

70. Muscles of the lower leg: topography and functions.

71. Muscles that flex and extend the lower leg.

72. Muscles that supinate and pronate the lower leg.

73. Muscles that flex and extend the foot.

74. Muscles that abduct and adduct the foot.

75. Muscles supinating and pronating the foot.

76. Muscles that hold the arches of the foot.

77. General center of gravity of the body: age, gender and individual characteristics of its location.

78. Types of balance: angle of stability, conditions for maintaining body balance.

79. Anatomical characteristics of anthropometric, quiet and tense body position.

80. Hanging on straight arms: anatomical characteristics, features of the external respiration mechanism.

81. General characteristics of walking.

82. Anatomical characteristics of 1, 2 and 3 phases of a double step.

83. Anatomical characteristics of the 4th, 5th and 6th phases of the double step.

84. Standing long jump: phases, muscle work.

85. Anatomical characteristics of a backflip.

60. Muscles that abduct and adduct the shoulder.

Shoulder abducted: deltoid muscle, supraspinatus muscle.

Deltoid

Supraspinatus muscle It starts from the supraspinatus fossa of the scapula and the fascia covering it, and is attached to the greater tubercle of the humerus and partly to the capsule of the shoulder joint. The function of the muscle is to abduct the shoulder and tighten the joint capsule of the shoulder joint.

Lead shoulder: pectoralis major muscle, latissimus dorsi muscle, subscapularis muscle, infraspinatus muscle.

Pectoralis major muscle

Latissimus dorsi muscle

Subscapularis muscle

Infraspinatus muscle

61. Muscles that supinate and pronate the shoulder.

Rotate the shoulder outward: deltoid muscle (posterior bundles), teres major muscle, infraspinatus muscle.

Deltoid starts from the clavicle (anterior part of the muscle), acromion (middle part) and the spine of the scapula (posterior part), and attaches to the deltoid tuberosity of the humerus. If the front and back parts alternately work, then the upper limb moves forward and backward, i.e. flexion and extension. If the entire muscle tenses, then its front and back parts form a resultant force, the direction of which coincides with the direction of the fibers of the middle part of the muscle, helping to abduct the shoulder to a horizontal level.

Teres major muscle starts from the lower angle of the scapula and is attached to the crest of the lesser tubercle of the humerus, often by one tendon from the latissimus dorsi muscle. When contracting, the teres major muscle acts as a rounded eminence when the pronated shoulder is adducted. The function of the muscle is to adduct, pronate and extend the humerus.

Infraspinatus muscle starts from the infraspinatus fossa of the scapula. In addition, the origin of this muscle is the infraspinatus fascia. Attached to the greater tubercle of the humerus. The function of the infraspinatus muscle is to adduct, supinate and extend the shoulder at the shoulder joint.

Rotate the shoulder inward: deltoid muscle (anterior bundles), pectoralis major muscle, latissimus dorsi muscle, teres major muscle, subscapularis muscle.

Deltoid

Pectoralis major muscle starts from the medial half of the clavicle (clavicular part), the anterior surface of the sternum and the cartilaginous parts of the upper five or six ribs (sternocostal part), the anterior wall of the rectus sheath (ventral part) and is attached to the crest of the greater tubercle of the humerus. It refers to the muscles that extend from the trunk to the free upper limb. This muscle pulls the scapula forward and away from the spinal column. But this function is secondary. Basically, it is involved in the movements of the humerus. If the torso is fixed, then this muscle adducts, pronates and flexes the humerus.

Latissimus dorsi muscle starts from the spinous processes of the lower five to six thoracic vertebrae, all lumbar, upper sacral vertebrae and from the posterior part of the iliac crest, with four teeth from the four lower ribs, attaches to the crest of the lesser tubercle of the humerus. By adducting and penetrating the humerus, it causes the lowering of the upper limb girdle and adduction of the scapula to the spinal column; that part of the muscle that starts from the ribs can lift them and have some effect on increasing the volume of the chest during inspiration.

Teres major muscle

Subscapularis muscle located on the anterior surface of the scapula, filling the subscapular fossa, from which it begins. The muscle is attached to the lesser tubercle of the humerus. It produces shoulder adduction; acting in isolation, it is its pronator.