The structure of the lower leg. Lower leg muscles, their location, functions and structure
Calf muscles, like other muscles lower limb, are well developed, which is determined by the function they perform in connection with upright posture, statics and dynamics of the human body. Having an extensive origin on the bones, intermuscular septa and fascia, the muscles of the lower leg act on the knee, ankle and foot joints.
Distinguish anterior, posterior and lateral muscle groups of the lower leg. The anterior group includes the tibialis anterior, extensor digitorum longus, and extensor pollicis longus muscles. To the rear group belong triceps calf (consisting of the gastrocnemius and soleus muscles), plantaris and popliteus muscles, flexor digitorum longus, flexor pollicis longus toe, tibialis posterior muscle. The lateral group of the tibia includes the short and long peroneus muscles.
Anterior calf muscle group
Tibialis anterior muscle(m.tibialis anterior) is located on the front side of the lower leg. It begins on the lateral condyle and the upper half of the lateral surface of the body of the tibia, as well as the adjacent part of the interosseous membrane and on the fascia of the leg. At the level of the distal third of the leg, muscle bundles pass into long tendon, which passes under the superior and inferior retinaculum of the extensor tendons, anterior to the ankle joint. Next, the tendon goes around the medial edge of the foot and attaches to the plantar surface of the medial cuneiform bone and the base of the first metatarsal bone.
Function: extends the foot in ankle joint, simultaneously raises the medial edge of the foot and turns it outward (supination), strengthens the longitudinal arch of the foot. With a fixed foot, the lower leg tilts forward; helps keep the shin in place vertical position.
Innervation:
Blood supply; anterior tibial artery.
Extensor digitorum longus(m. extensor digitorum longus) - a pinnate muscle, begins on the lateral condyle of the tibia, the anterior surface of the body of the fibula, on the upper third of the interosseous membrane, fascia and anterior intermuscular septum of the leg (Fig. 188). Heading towards the dorsum of the foot, the muscle passes behind the superior and inferior retinaculum of the extensor tendons. At the level of the ankle joint, the muscle is divided into 4 tendons, which are enclosed in a common synovial sheath. Each tendon is attached to the dorsum of the base of the middle and distal phalanges of the II-V fingers.
A small bundle is separated from the lower part of the muscle, called the third peroneal muscle (m.peroneus tertius), the tendon of which is attached to the base of the V metatarsal bone.
Function: extends the II-V fingers at the metatarsophalangeal joints, as well as the foot at the ankle joint. The third peroneus muscle elevates the lateral edge of the foot. With a strengthened foot, the extensor digitorum longus holds the lower leg in a vertical position.
Innervation: deep peroneal nerve(L IV -S I).
Blood supply: anterior tibial artery.
Extensor hallucis longus(m.extensor hallucis longus) is located between the tibialis anterior muscle medially and the extensor digitorum longus muscle laterally; partially covered by them in front. It begins on the middle third of the anterior surface of the fibula, the interosseous membrane of the leg. The muscle tendon passes down the dorsum of the foot under the superior and inferior extensor tendon retinaculum in a separate synovial sheath and inserts on the distal phalanx of the big toe. Individual tendon bundles can also attach to the proximal phalanx.
Function: extends the big toe; also participates in the extension of the foot at the ankle joint.
Innervation: deep peroneal nerve (L IV -S I).
Blood supply: anterior tibial artery.
Posterior calf muscle group
The muscles of the posterior group form two layers - superficial and deep. The superficial triceps surae muscle is more strongly developed, which creates the roundness of the lower leg characteristic of humans (Fig. 189). The deep layer is formed by a small popliteus muscle and 3 long muscles: flexor digitorum longus (located most medially), tibialis posterior muscle (occupies an intermediate position) and flexor hallucis longus (located laterally) (Fig. 190).
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The main functions of the lower leg muscles are the following: maintaining the body in an upright position and moving it along the ground. In this regard, they all go in the longitudinal direction and are attached to the foot. Due to the fact that the most massive parts of the muscles are located in the proximal part of the lower leg, and the distal parts pass into narrow tendons, the lower leg has a conical shape.
There are anterior, lateral and posterior groups of muscles of the lower leg. The anterior group of shin muscles provides dorsiflexion of the foot and extension of the toes. The lateral group of lower leg muscles performs plantar flexion of the foot. The posterior group of muscles of the lower leg performs plantar flexion of the foot and flexion of the toes. Pronation and supination are carried out by those muscles of the lower leg that are attached to the medial or lateral edge of the foot.
The anterior group of leg muscles is located along the anterior surface of the tibia and fibula. It consists of the following muscles: tibialis anterior muscle (m. tibialis anterior), long extensor digitorum (m. extensor digitorum longus), long extensor pollicis (m. extensor hallucis longus).
Tibialis anterior muscle
M. tibialis anterior
The most medial and most strong muscle this group. It has a wide origin from the lateral condyle, the proximal two-thirds of the tibia and from the interosseous membrane. In the lower third of the tibia it passes into a strong and flat tendon, which is attached to the plantar surface of the medial sphenoid bone and to the base of the first metatarsal bone.
The tibialis anterior muscle (m. tibialis anterior) is shown in Fig. 1.
Rice. 1. Tibialis anterior muscle (m. tibialis anterior)
Function:
- dorsiflexion of the foot;
- foot supination and adduction;
- bending the shin forward at the ankle joint (with a fixed foot).
Extensor digitorum longus
M. extensor digitorum longus
Located lateral to the previous muscle. It starts from the upper third of the tibia, the upper part of the fibula, and from the interosseous membrane. At the border of the middle and lower thirds of the leg muscle fibers pass into a tendon, which extends onto the foot and divides into four tendons. They are fan-shaped attached to the tendon stretch on the back of the II-V fingers.
In some cases, a small muscle bundle is separated from the distal part of this muscle on the lateral side, giving rise to the fifth tendon, which is attached to the base of the fifth metatarsal bone. This unstable muscle bundle is called the third peroneal muscle (m. peroneus tercius). It is involved in the pronation of the foot, necessary for bipedal walking.
The long extensor digitorum (m. extensor digitorum longus) is shown in Fig. 2.
Rice. 2. Anterior group of lower leg muscles:
1 - extensor digitorum longus (m. extensor digitorum longus);
Posterior muscle group of the lower leg.
Superficial layer (calf muscles):
M. triceps surae, triceps surae muscle, forms the main mass of the calf elevation. It consists of two muscles - m. gastrocnemius, located superficially, and m. soleus, lying under it; both muscles below have one common tendon.
- M. gastrocnemius, gastrocnemius muscle, starts from facies poplitea femur behind both condyles there are two heads, which with their tendon origin are fused with the capsule of the knee joint. The heads pass into the tendon, which, merging with the tendon m. soleus, continues into the massive Achilles tendon, tendo calcaneus (Achillis), attached to back surface tubercle of the calcaneus. At the point of attachment between the tendon and the bone there is a very permanent synovial bursa, bursa tendinis calcanei (Achillis).
- M. soleus, soleus muscle, thick and fleshy. It lies under the calf muscle, occupying a large area on the bones of the lower leg. The line of its origin is located on the head and on the upper third of the posterior surface of the fibula and descends along the tibia almost to the border of the middle third of the tibia with the lower one. In the place where the muscle spreads from the fibula to the tibia, a tendon arch is formed, arcus tendineus m. solei, under which the popliteal artery and n. tibialis. Tendon sprain m. soleus merges with the Achilles tendon.
M. plantaris, plantaris muscle. It originates from the facies poplitea above the lateral condyle of the femur and from the capsule of the knee joint, soon passing into a very long and thin tendon that stretches in front of the m. gastrocnemius and attaches to the calcaneal tubercle. This muscle undergoes reduction and in humans is a rudimentary formation, as a result of which it may be absent. Function. All muscles m. triceps surae (including m. plantaris) produces flexion at the ankle joint both with the free leg and with support on the end of the foot. Since the line of pull of the muscle passes medially to the axis of the subtalar joint, it also causes adduction of the foot and supination. When standing, the triceps surae (especially the m. soleus) prevents the body from tipping forward at the ankle joint. The muscle has to work primarily when burdened by the weight of the whole body, and therefore it is strong and has a large physiological diameter; m. gastrocnemius, as a biarticular muscle, can also flex the knee when the lower leg and foot are strengthened. (Inn. m. triceps surae and m. plantaris - L5-S2. N. tibialis.) The deep layer, separated from the superficial by the deep fascia of the leg, is composed of three flexors, which oppose the three homonymous extensors lying on the anterior surface of the leg.
M. flexor digitorum longus, long flexor digitorum, the most medial of the muscles of the deep layer. It lies on the posterior surface of the tibia, from which it originates. The tendon of the muscle descends behind the medial malleolus, in the middle of the sole it divides into four secondary tendons, which go to the four fingers II-V, pierce the tendon m. flexor digitorum brevis and are attached to the distal phalanges. The function in terms of bending the fingers is small; the muscle mainly acts on the foot as a whole, producing flexion and supination when the leg is free. She also, together with m. triceps surae is involved in placing the foot on the toe (walking on tiptoes). When standing, the muscle actively helps strengthen the arch of the foot in the longitudinal direction. When walking, presses fingers to the ground. (Inn. L5-S1. N. tibialis.)
M. tibialis posterior, tibialis posterior muscle, occupies the space between the bones of the leg, lying on the interosseous membrane and partly on the tibia and fibula. From these places the muscle receives its initial fibers, then with its tendon it bends around the medial malleolus and, reaching the sole, is attached to the tuberositas ossis navicularis, and then by several bundles to the three wedge-shaped bones and the bases of the II-IV metatarsal bones. Function. Bends the foot and brings it together with m. tibialis anterior. Together with other muscles also attached to the medial edge of the foot (m. tibialis anterior et m. peroneus longus), m. tibialis posterior forms a kind of stirrup, which strengthens the arch of the foot; stretching its tendon through the lig. calcaneonavicular, the muscle supports the head of the talus together with this ligament. (Inn. L5-S1. N. tibialis.)
M. flexor hallucis longus, long flexor of the big toe, the most lateral of the deep layer muscles. Lies on the posterior surface of the fibula, from which it originates; the tendon runs in a groove on the processus posterior of the talus, approaches the sustentaculum tali to the big toe, where it attaches to its distal phalanx. Function. Flexes the thumb, and also due to a possible connection with the tendon of the m. flexor digitorum longus can act in the same sense on Pi even on fingers III and IV. Like the rest posterior muscles shin, m. flexor hallucis longus produces flexion, adduction and supination of the foot and strengthens the arch of the foot in the anteroposterior! direction. (Inn. L5-S2. N. tibialis.)
Anatomy of the human lower leg - a complex system interconnected muscles, bones and ligaments. The development of the lower leg muscles determines their structure, as is the case with the muscular apparatus of the thigh or pelvic region - all these areas are responsible for the ability to walk upright, and this type of movement implies high load. The entire muscular complex of the lower leg, intermuscular septa and fascia of the leg (FG) is responsible for the correct functioning of the knees, ankles and feet.
Calf muscles: location, functions
This zone is included in the leg and runs from the knee to the foot. The skeletal foundation of the site is built on only two components - the tibia and fibula. The muscles cover them on 3 sides. Complex functionality:
- implementation of movement;
- flexion/extension of joint mechanisms.
Tibial segment
Classified as part of the anterior calf muscle group. This system controls the area of the skeletal apparatus of the limb in question. The tibialis anterior muscle (TAM) begins to develop on the outer plane of the bone of the same name. Subsequently, it moves further than the lower and upper retinaculum, which extend the fibers, which are enlarged processes of the ankle and foot fascia and develop on the lower leg. The PBM is then attached to the base of the growth of the first metatarsus, as well as to the medial cuneiform bone.
The muscle is easy to feel through the skin, this is especially noticeable in the place where the foot begins, because the connecting tendon of the fiber protrudes outward. It works as an extensor of the lower leg muscles and additionally serves as an instep support.
Extensor digitorum (long)
The DRP is localized on top of the previously mentioned element in the initial segment. Growth starts from the tip of the tibia and the frontal marginal surface of the fibula, from the FG and the interosseous membrane. At the foot level, fiber separation occurs into 5 tendons (T):
- 4 are attached to toes 2 to 5;
- the latter - to the beginning of the 5th metatarsal bone.
The extensor digitorum longus also performs the function of the foot, which is clear from its name. Thanks to the tendon attachment to the outside of the foot, the element also has the ability to pronate.
Extensors of the thumbs
Between the middle of the PBM and the side of the DRP, in some places covered in the anterior region by these muscles, there is a long extensor pollicis. It is formed in the second third of the frontal surface of the fibula and the joints of the lower leg elements. The tendons belonging to the muscle move towards the heel, spreading behind the holders mentioned above in a separate synovial sheath, after which they join the distal phalanx of the big toe as a whole, and optionally to the one next to the nail. The task of the muscle of the anterior surface of the leg is to straighten the joint and provide motor ability foot area in the ankle.
Flexor digitorum
The flexor digitorum longus (flexor digitorum longus) arises from the dorsum of the tibia and moves toward the sole, sliding behind the medial malleolus in a special channel that lies below the fixator.
Near the plantar surface, the Digitorum longus runs through the tendon that flexes the big toe; the quadratus muscle is attached to it, which subsequently disperses into 4 striated muscles connected to the DF (distal phalanges) from the second to 5th toes.
The element supinates the foot and causes the toes to clench. The task of the quadratus muscle is to balance the impact, which is necessary because... the divided part of the chipboard performs flexion and also balances the limb to the midplane of the body. The attached muscular structure pulls outward, the adductive effect weakens, and flexion occurs rather in the vertical plane of the body.
Triceps surae muscle
Belongs to the muscles of the back of the lower leg. The name is due to its structure, because has three muscle ends (heads):
- the first and second are closer to the dermis and form the calves;
- the third lies deeper in the limbs and makes up the soleus muscle, holding the area on the talus without moving it forward.
The processes connect to form the Achilles tendon, which is attached to the tubercle of the calcaneus.
The medial and lateral condyles of the femoral region are the starting point for calf growth. The second head is less developed than the first, descending a little further. They have two bending tasks:
- in the knee;
- ankle joint.
The soleus head grows from the dorsal part of the upper third of the BB bone and from the tendon between the tibia and fibula of the skeleton. Located behind the subtalar joint and ankle, the fiber regulates the flexion of the medial edge of the foot.
In the superficial visible part, the triceps surae muscle is visually distinguished and can be examined by touch without difficulty. It is characterized by a maximum range of rotation perpendicular to the ankle joint due to the fact that the ligaments on the heel in the rear of the foot stand out behind the mentioned axis.
The diamond-shaped popliteal fossa is formed by the heads of the gastrocnemius muscle. The rhombus is limited by the posterior group of muscles of the lower leg, as well as:
- The anterosuperior part is the biceps femoris muscle.
- Back and top – semimembranosus muscle.
- In the lower part are the plantaris muscle and the ends of the gastrocnemius.
- The bottom is the capsule of the knee joint and the femur.
Along the bottom are threads of nerve endings and arteries that feed and control muscle and bone tissue.
Flexor pollicis
The most powerful muscle in the lower leg - hallucis longus - develops from the bottom of the dorsal section of the ankle joint and the dorsal membrane. Near the sole, the muscle lies in the middle of the components of the flexor muscle minor and grows from the beginning of the distal phalanx of the first finger.
The purpose of the existence of the long flexor tendon of the thumb, or first, finger in the body is to compress it and the foot.
Due to partial fusion with the flexor tendon, the position of the second and third fingers is affected. There are 2 sesamoid bones near the metatarsophalangeal joint; thanks to them, the torque of the DSBP increases.
Tibialis posterior muscle
It is localized deeper than the triceps muscle between the flexor muscles of the leg. The beginning is the back side of the interosseous septum and the adjacent parts of the tibia. After passing through the medial malleolus, the muscle attaches to the tubercle of the scaphoid and sphenoid bones, to the metatarsus. The tibialis posterior muscle, which belongs to the adductor muscles of the leg, is responsible for the following actions:
- bringing the foot into motion;
- supination;
- flexion.
The fiber is separated from the soleus muscle by a canal, the so-called. tibial-popliteal, in front appearance resembling a thin slit. In its bed lie nerve fibers and blood vessels.
Second division of tibial fibers
It begins to form in the same place as the muscle described above and is located in a mass of tissue, unlike the triceps muscle. Attached to the metatarsal, sphenoid and navicular bones. This fragment lateral group The muscles of the lower leg, combined with the ZBBM, bend and move the foot.
Popliteal segment
Consists of a complex of interconnected small fibers lying near the surface of the knee. They go through:
- from the lateral femoral condyle;
- deeper than the calf area and knee synovial bursa;
- rise above the soleus muscle and are attached to the tibia.
Since the muscle strips are partially attached to the knee bursa, the bursa is pulled back during flexion.
The functional tasks performed by the popliteus muscle include:
- ensuring leg mobility;
- her natural pronation.
Long fibular segment
A distinctive feature of the site is its feathery structure. The muscle lies on top of the MB of the bone, is attached to its 2 thirds from the outer part, growing from:
- its head part;
- partially – fascia;
- LBC condyle.
When the peroneus longus muscle contracts, 3 types of movement are provided at once:
- abduction;
- pronation (bending);
- the leg bends at the foot.
The tendon of this fiber wraps around the lateral part of the ankle behind and below. Near the heel they meet the extreme retinaculum. Having moved further and being surrounded by the muscles of the sole, the element spreads along a groove running along the lower surface of the cuboid bone of the foot and ends on its inner side.
Short fibular fibers
It is this subtype of flat muscular formations that raises the lateral edge of the foot, does not allow it to turn with the plantar side inward and clubfoot, and performs plantar flexion.
The short MB fiber is formed by the fusion of the crural septa and the fibula on its superficial side facing the skin. As the tendon moves downward and is released from the peroneus brevis muscle, it fits around the malleolar lateral structure from the dorsal lower edge, after which it is attached to the tuberosity of the last metatarsal bone.
Common malformations
In addition to serious but rare anomalies such as the absence of one of the limbs or some of their parts, fusion together and other global defects, among the pathologies of the formation of bones and muscles of the leg there are:
- Curvature of the leg in the frontal plane - may go away on its own after the baby learns to walk independently, and no treatment is required.
- Native subluxation or dislocation is often bilateral; it is accompanied by a change in the shape of the knees and contracture. The type of deformity diagnosed depends on the strength and nature of the changes. The changes are due to the fact that the muscles are not attached in the places where they should, due to the underdevelopment of the femur and shin bones. This pathology may be accompanied by problems with the structure and function of the ankle, insufficient development or complete absence of the tibia.
- Hypoplasia (underdevelopment and small size) of elements.
- The presence of false joints, constriction of the ligaments of the feeding nodes.
Even with proper development As the leg structures grow, abnormalities may appear caused by a deficiency of bone mineralization, inflammation in the joints and muscles, excessive or insufficient loads, injuries, improper selection of shoes or poor nutrition.
The lower leg is a complex structure consisting of many finely adjusted components, so this part of the body can be subject to pathological changes. High permanent load increases the risk of developing diseases and defective conditions. It needs to be given attention in general health care, especially in infants. initial stages postnatal development and in older people due to the vulnerability of joints and fragility of bone tissue. When eating, it is necessary to maintain the level of beneficial microelements for the human skeleton by periodically taking a complex of vitamins. It is also necessary to monitor the condition of the joints,, if possible, reduce the load on the limbs with the help of specialized orthopedic devices and develop muscles.
The tibia refers to the lower limb. It is located between the foot and the knee area. The lower leg is formed by two bones - the fibula and the tibia. They are surrounded by muscle fibers on three sides. The muscles of the lower leg, the anatomy of which will be discussed later, move the fingers and foot.
Tibia
This element has an extension at the top edge. In this area, condyles are formed: lateral and medial. On top of them are the surfaces of the joints. They articulate with the femoral condyles. On the outside of the lateral segment there is an articular surface through which the connection occurs with the head of the fibula. The body of the tibial element looks like a triangular prism. Its base is directed posteriorly and has, respectively, 3 surfaces: posterior, external and internal. Between the last two there is an edge. It's called the front one. In its upper part it passes into the tibial tuberosity. This area is intended for fixation. The lower part of the tibia has an extension, and on inner surface there is a protrusion. It is oriented downward. This projection is called the medial malleolus. On the back side of the bone lies a rough segment of the soleus muscle. The distal epiphysis contains the articular surface. It serves to connect with
Second element
The fibula is thin, long, and located laterally. Its upper end has a thickening - a head. She connects with tibia. Lower section the element is also thickened and forms the lateral malleolus. It, like the head of the fibula, is oriented outward and can be easily palpated.
Calf muscles: their location, functions
The fibers are located on three sides. Highlight different muscles shins. The anterior group performs extension of the foot and toes, supination and adduction of the foot. This segment includes three types of fibers. The tibialis anterior muscle of the leg is the first to be formed. The remaining fibers form long extensors fingers and a separate one for the big toe. The posterior group of muscles of the lower leg forms a larger number of fibers. In particular, there are long flexors of the fingers and, separately, for the thumb, popliteus, and triceps surae muscles. Tibial fibers also lie here. TO outdoor group include the short and long peroneus muscles of the leg. These fibers flex, pronate and abduct the foot.
Tibial segment
This anterior muscle of the leg begins from the bone of the same name, its outer surface, fascia and interosseous membrane. They are directed downwards. The fibers pass under two ligaments. They are located in the ankle area. These areas - the upper and lower retinaculum of the extensor tendons - are represented by places of thickening of the fascia of the foot and lower leg. The site of attachment of the fibers is the medial wedge and the base of the metatarsal (first) bone. The muscle can be palpated quite well along its entire length, especially in the area where it transitions to the foot. In this place, its tendon protrudes during extension. The task of this calf muscle is to supinate the foot.
Extensor digitorum (long)
It runs from the anterior muscle outward into upper area shins. Its fibers begin from the head and marginal areas of the tibia, fascia and interosseous membrane. The extensor, moving to the foot, is divided into five tendons. Four are attached to the distal ones (second to fifth), the last one to the base of the 5th metatarsal. The task of the extensor, acting as a multi-joint muscle of the leg, is not only to coordinate the extension of the fingers, but also the foot. Due to the fact that one tendon is fixed at its edge, the fibers also pronate the area somewhat.
Extensors of the thumbs
The fibers begin in the area of the lower leg from the interosseous membrane and the inner part of the fibula. The extensors have less strength than the segments described above. The site of attachment of this is the distal phalanges in thumbs. These muscles of the lower leg not only extend them, but also the feet, also contributing to their supination.
Flexor digitorum (long)
It starts from the back of the tibia, passing under the medial malleolus onto the foot. The channel for it is located under the retinaculum. Next, the muscle is divided into four segments. On the foot (its plantar surface), fibers cross the tendon from the flexor (long) hallux. Then they are joined by the quadratus plantae muscle. Four formed tendons are fixed to the distal phalanges (at their base) of 2-5 fingers. The task of this muscle is, among other things, to flex and supinate the foot. The fibers of the quadrate segment are attached to the tendon. Due to this, the muscle action is averaged. Lying under the medial malleolus and dividing fan-shaped towards the phalanges, the long flexor also provokes some adduction of the fingers to the median surface of the body. By pulling quadratus muscle tendons, this effect is slightly reduced.
Triceps surae muscle
It runs along the back surface and has 3 heads. Two form the superficial section - the gastrocnemius muscle, from the third - the deep one - the fibers of the soleus segment depart. All heads connect and form the common Achilles (heel) tendon. It is attached to the tubercle of the corresponding bone. Calf muscle starts from the femoral condyles: lateral and medial. The purpose of the two heads located in this area is twofold. They coordinate flexion at the knee joint and foot flexion at the ankle. The medial element descends slightly lower and is better developed than the lateral one. The soleus muscle extends from the posterior side of the upper third of the tibia. It is also attached to the arch of tendon located between the bones. The fibers run somewhat lower and deeper than the calf. They lie behind the subtalar and cause flexion of the foot. The triceps muscle can be felt under the skin. The calcaneal tendon protrudes posteriorly from the transverse axis of the ankle joint. Due to this, the triceps muscle has a large torque relative to this line. The heads of the gastrocnemius segment participate in the formation of the rhomboid popliteal fossa. Its boundaries are: the biceps femoris muscle (outside and above), semimembranous fibers (inside and above), the plantar and two heads of the gastrocnemius segment (below). The bottom of the fossa is formed by the capsule of the knee joint and the vessels and nerves that supply the foot and lower leg run through this area.
Flexor pollicis longus
This muscle of the posterior surface of the leg is characterized greatest strength. On the plantar side of the foot, fibers run between the heads from a short segment responsible for flexion of the big toe. The muscle begins from the posterior side (lower part) of the fibula and the intermuscular septum (posterior). The site of fixation is the plantar surface of the base of the distal phalanx in the big toe. Due to the fact that the tendon of the muscle partially passes into the long flexor element of the same name, it has some influence on the movements of 2-3 fingers. The presence of 2 large sesamoid bone elements on the surface of the sole of the metatarsophalangeal joint provides an increase in the moment of rotation of the fibers. The tasks of the segment include flexion of the entire foot and big toe.
Second division of tibial fibers
This posterior segment is located under the triceps muscle. The fibers begin from the interosseous membrane and the areas of the fibula and tibia adjacent to it. The site of attachment of the muscle is the tubercle of the scaphoid, the base of the metatarsals and all wedge-shaped elements. The muscle lies under the medial malleolus and performs flexion of the foot, supination and adduction. A canal passes between the soleus and tibial fibers. It is presented in the form of a slit. Nerves and blood vessels pass through it.
Popliteal segment
It is formed by flat short fibers. The muscle is directly adjacent to knee joint behind. The fibers originate from the femoral condyle (lateral), below the gastrocnemius, and the bursa of the knee joint. They pass down and attach above the soleus muscle to the tibia. Because the fibers are partially attached to the joint capsule, they pull it posteriorly when flexed. The task of the muscle is to pronate and flex the lower leg.
Long fibular segment
This muscle has a feathery structure. It runs along the surface of the fibula. It starts from its head, the condyle of the tibial element, partly from the fascia. It is also attached to the 2-thirds area outside fibula. When the muscle contracts, abduction, pronation and flexion of the foot occur. The tendon of the long peroneal segment passes posteriorly and inferiorly around the lateral malleolus. In the area of the heel bone there are ligaments - the upper and lower retinaculum. When moving to the plantar part of the foot, the tendon runs along the groove. It is located on the underside of the cuboid bone. The muscle reaches the inside of the foot.
Short fibular fibers
The tendon of the segment bends around the lateral malleolus posteriorly and inferiorly. It is attached to the tubercle on the 5th metatarsal bone. The segment begins from the intermuscular septa and the outer part of the fibula. The task of the fibers is abduction, pronation and flexion of the foot.
