Muscles of the shin, their location, function and structure. Anterior and posterior groups of lower leg muscles

The lower leg refers to the lower extremity. It is between the foot and the knee area. Shin was formed by means of two bones - small and tibial. They are surrounded by muscular fibers from three sides. The muscles of the lower leg, the anatomy of which will be discussed later, set the fingers and the foot in motion.

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 perform an articulation with the hip condyle. On the lateral segment, from the outside, there is an articular surface, through which a connection to the head in the fibula occurs. The body of the tibial element looks like a trihedral prism. Its base is directed posteriorly and has 3 surfaces, respectively: posterior, external and internal. Between the last two is the edge. It's called the front. In its upper part it passes into the tuberosity of the tibia. This area is designed to fix the tendon of the quadriceps femoris muscle. In the lower part, the tibia has an extension, and there is a projection on the inner surface. It is oriented downwards. This protrusion is called the medial ankle. On the back of the bone lies a rough segment of soleus muscle. On the distal epiphysis is the articular surface. It serves to connect with the talus bone.

The second element

The fibula is thin, long, located laterally. Its upper end has a thickening - the head. It connects to the tibia. The lower part of the element is also thickened and forms the lateral ankle. It, like the head of the fibula, is oriented to the outside and is well probed.

Muscles of lower leg: their location, functions

The fibers are arranged on three sides. Alloculate different muscles of the shin. The front group performs extension of the foot and toes, supination and reduction of the foot. This segment includes three types of fibers. The tibial anterior tibialis muscle is formed first. The remaining fibers form long extensor fingers and separate for the thumb on the foot. The posterior group of the calf muscles forms more fibers. In particular, here there are long flexors of the fingers and separately - for the large, popliteal, triceps muscle of the shin. Also here lie the tibia. The outer group includes the short and long fibular muscles of the shin. These fibers fold, pierce and drain the foot.

Tibial segment

This anterior muscle of the leg begins with the same bone, its outer surface, fascia and the interosseous membrane. They are directed downwards. The fibers pass under two bundles. They are located in the ankle and ankle. These areas - the upper and lower extensor tendons of the extensors - are represented by the sites of thickening of the fascia of the foot and lower leg. The area of fiber attachment is the wedge medial and the base of the metatarsal (first) bone. The muscle is probed well enough throughout its entire length, especially at the site of the transition to the foot. At this point its tendon protrudes when extending. The task of this leg muscle is the supination of the foot.

Extensor of fingers (long)

It runs from the anterior muscle to the outside in the upper region of the shin. Its fibers start from the head and margins of the tibia, the fascia and the interosseous membrane. Extensor, moving to the foot, is divided into five tendons. Four are attached to the distal phalanx of the fingers (from the second to the fifth), the latter to the base of the 5th metatarsal bone. The problem of the extensor, which acts as a multi-joint muscle of the shin, consists not only in coordinating the extension of the fingers, but also in the foot. Due to the fact that one tendon is fixed on its edge, the fibers also penetrate the area somewhat.

Thumb extensors

Fibers begin in the lower part of the lower leg from the interosseous membrane and the inner part of the fibula. Extensors are less powerful than the segments described above. The attachment site for this is the distal phalanges in the thumbs. These muscles of the lower leg not only carry out their extension, but also stop, also contributing to their supination.

Finger bend (long)

It starts from the back of the tibia, passing under the medial ankle to the foot. The channel for it is located under the holder (bundle) of tendons-flexors. Then the muscle is divided into four segments. On the foot (its sole surface), the fibers cross the tendon from the flexor (long) of the thumb. Then a square muscle of the sole joins them. Four formed tendons are fixed to the distal phalanges (at their base) 2-5 fingers. The task of this muscle consists, among other things, in flexion and supination of the foot. Fibers of a square segment attach to the tendon. This results in averaging the action of the muscle. Passing under the medial ankle and dividing fanwise in the direction of the phalanx, the long flexor provokes some of the fingers to the middle surface of the body. Due to the pulling of the tendon by the square muscle, this action decreases slightly.

The triceps musculature of the lower leg

It runs along the back surface and has 3 heads. Two form the surface area - the gastrocnemius muscle, from the third - deep - the fibers of the sole segment leave. All the heads join and form a common Achilles tendon. It is attached to the bug of the corresponding bone. The gastrocnemius muscle starts from the femoral condyles: lateral and medial. The task of the two heads located in this area is twofold. They coordinate the flexion in the knee joint and the foot - in the ankle. The medial element descends slightly lower and is developed better than the lateral one. From the back side in the upper third of the tibia descends the soleus muscle. It also attaches itself to a tendon arc located between the bones. The fibers pass somewhat lower and deeper than the calves. They lie behind the subtalar and ankle joints and cause flexion of the foot. The triceps muscle can be probed under the skin. From the transverse axis in the ankle joint, the heel tendon protrudes posteriorly. Due to this, the triceps muscle has a relatively high torque relative to this line. The head of the gastrocnemius segment is involved in the formation of a rhomboid popliteal fossa. As its boundaries are: two-headed femoral muscle (from the outside and from above), semimembranous fibers (inside and on top), plantar and two heads of the gastrocnemius segment (from below). The bottom in the pit is formed by the capsule of the knee joint and the femur. Through this site lie the vessels and nerves that feed the foot and shin.

Thumb flexor (long)

For this muscle, the posterior surface of the shin is characterized by the greatest strength. On the plantar side of the foot, the fibers run between the heads from the short segment responsible for flexing the thumb. The muscle begins from the back (bottom) of the fibula and the intermuscular septum (posterior). The fixation site is the plantar surface of the base of the distal phalanx in the thumb. Due to the fact that in part the muscle tendon passes into the same element of the long flexor, it has some influence on the movements of 2-3 fingers. The presence on the surface of the sole of the metatarsus-phalangeal joint of 2 large sesamoid bone elements provides an increase in the moment of rotation of the fibers. The task of the segment includes bending the entire foot and thumb.

Second section of tibial fibers

This posterior segment is located under the triceps muscle. Fibers begin from the interosseous membrane and the areas of the small and tibia bones adjacent to it. The site of attachment of the muscle is the scaphoid, the base of the metatarsal and all the wedge-shaped elements. The muscle lies under the medial malleolus and performs flexion of the foot, supination and its reduction. Between the sutural and tibial fibers passes the canal. It is presented in the form of a gap. Nerves and blood vessels pass through it.

Popliteal segment

It is formed by flat short fibers. The muscle adjoins directly to the knee joint from behind. Fibers begin from the femoral condyle (lateral), below the gastrocnemius segment, and the knee joint bags. They pass down and are attached above the soleus muscle to the tibia. Since the fibers are partially attached to the capsule of the joint, when bent, they pull it backward. The task of the muscle is pronation and flexion of the shin.

Long fibular segment

This muscle is distinguished by a pinnate structure. It lies on the surface of the fibula. It starts from her head, the condyle of the tibial element, partly from the fascia. It is also attached to the area of 2/3 of the outer side of the fibula. With the contraction of the muscle occurs the withdrawal, pronation and flexion of the foot. The tendon of the long fibular segment behind and below traverses the lateral ankle. In the region of the heel bone, there are ligaments - the upper and lower retainers. When moving to the plantar part of the foot, the tendon lies along the furrow. 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 curves around the back and bottom of the lateral ankle. It is attached to the tubercle on the metatarsal bone. The segment begins from the intermuscular partitions and the outer part of the fibula. The task of fibers is the removal, pronation and flexion of the foot.