Quadratus pedis muscle. Foot muscles

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On the dorsum of the foot there are two small muscles, often fused at their origin: the extensor digitorum brevis and the extensor digitorum brevis thumb.

Extensor digitorum brevis

Extensor digitorum brevis (i.e. extensor digitorum brevis) lies under the tendons extensor longus. Starting from the anterior part of the calcaneus, the muscle is divided into four flat bellies, passing in front along with the tendons of the long extensor of the 1st – 4th fingers and the long extensor of the pollicis into the dorsal tendon extension on the phalanges of the 1st – 4th fingers. The muscle extends the fingers.

Muscles of the sole

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On the sole, the muscles are covered with a very dense, especially in the middle part, fascia, called plantar aponeurosis(Fig. 1.58). The latter is fixed on the heel tubercle, in the area of the metatarsus it is firmly fused with the skin, and along the edges of the foot it turns into a thin dorsal fascia of the foot. The lateral and medial intermuscular septa extend deeper from the plantar aponeurosis. They divide the muscles of the sole into three groups - medial, lateral and middle.

The medial group is formed short muscles thumb - flexor, abductor And adductor(Fig. 1.58). The latter also strengthens the transverse arch of the foot.

The lateral group includes short muscles of the fifth finger.

Most developed middle group plantar muscles, consisting of the short flexor digitorum, quadratus muscle soles, lumbrical and interosseous muscles of the foot.

Rice. 1.58. Muscles of the plantar side of the foot

Rice. 1.58. Muscles of the plantar side of the foot:
1 – worm-shaped;
2 – flexor pollicis brevis;
3 – tendon flexor longus thumb;
4 – abductor pollicis muscle;
5 – plantar aponeurosis (cut off);
6 – flexor digitorum brevis;
7 – quadratus plantae muscle;
8 – short muscles of the fifth finger;
9 – peroneus longus tendon;
10 – adductor pollicis muscle

Flexor digitorum brevis

Flexor digitorum brevis (t. flexor digitorum brevis), starting from the tubercle of the calcaneus and the plantar aponeurosis, it is divided into four abdomens (Fig. 1.58). The tendons of the latter, splitting into two legs, are attached to the lateral surfaces of the middle phalanges of the II–V fingers; The tendons of the flexor digitorum longus pass between the legs. The muscle flexes the toes and supports the longitudinal arch of the foot.

Quadratus plantar muscle

Quadratus plantar muscle (t. quadratus plantae) located under the flexor digitorum brevis (Fig. 1.58). It starts from the calcaneus and attaches to the lateral edge of the flexor digitorum longus tendon. The significance of the muscle comes down to establishing the longitudinal direction of thrust of the flexor digitorum longus, the tendon bundles of which approach the fingers obliquely.

Vermiform muscles of the foot

Vermiform muscles of the foot (tt. lumbricales pedis) in the form of four weak muscle bundles, they begin from the four tendons of the flexor digitorum longus; distally, the muscles are attached to the medial edges of the main phalanges of the II–V fingers, partially passing into their dorsal tendon extension. The muscles flex the main phalanges, straightening the middle and nail ones.

Interosseous muscles of the foot

Interosseous muscles of the foot (vt. interossei pedis) – four dorsal and three plantar, located in the intermetatarsal spaces. The muscles move the fingers along the sagittal axis, i.e. they are brought in and taken away.

The tendons of the long muscles, running on the sole and back of the foot, are located in the synovial sheaths, which facilitate their gliding. Where they pass under the fascial ligaments, the tendons are enclosed in osteofibrous canals and pressed against the bones. On the plantar side of the fingers, the flexor tendons, as on the fingers, pass through the osteofibrous and synovial sheaths.

The foot, as well as the hand, except for the tendons belonging to the lower leg long muscles, has its own short muscles; These muscles are divided into dorsal (dorsal) and plantar.

Dorsal foot muscles. M. extensor digitorum brevis, short extensor digitorum, located on the back of the foot under the long extensor tendons and originates on the calcaneus before entering the sinus tarsi.

Going forward, it is divided into four thin tendons to the I-IV fingers, which join the lateral edge of the tendons of m. extensor digitorum longus and m. extensor hallucis longus and together with them form the dorsal tendon stretch of the fingers. The medial belly, which runs obliquely along with its tendon to the big toe, also has a separate name m. extensor hallucis brevis.

Function. Extends fingers I-IV along with slight abduction to the lateral side. (Inn. L4-S1, N. peroneus profundus.)

Plantar muscles of the foot. They form three groups: medial (thumb muscles), lateral (little finger muscles) and middle, lying in the middle of the sole.

A) There are three muscles of the medial group:

1. M. abductor hallucis, abductor muscle toe, located most superficially on the medial edge of the sole; originates from the processus medialis of the calcaneal tubercle, retinaculum mm. flexdrum and tiberositas ossis navicularis; attaches to the medial sesamoid bone and the base of the proximal phalanx. (Inn. L5-S2 N. plantaris med.).

2. M. flexor hallucis brevis, short flexor of the big toe, adjacent to the lateral edge of the previous muscle, begins on the medial sphenoid bone and on the lig. calcaneocuboideum plantare. Going straight forward, the muscle divides into two heads, between which the m tendon passes. flexor hallucis longus.

Both heads are attached to the sesamoid bones in the area of the first metatarsophalangeal joint and to the base of the proximal phalanx of the big toe. (Inn. 5i_n. Nn. plantares medialis et lateralis.)

3. M. adductor hallucis, muscle that adducts the big toe, lies deep and consists of two heads. One of them (oblique head, caput obliquum) originates from the cuboid bone and lig. plantare longum, as well as from the lateral sphenoid and from the bases of the II-IV metatarsal bones, then goes obliquely forward and somewhat medially.

The other head (transverse, caput transversum) gets its origin from the articular capsules of the II-V metatarsophalangeal joints and plantar ligaments; it runs transversely to the length of the foot and, together with the oblique head, is attached to the lateral sesamoid bone of the big toe. (Inn. S1-2. N. plantaris lateralis.)

Function. The muscles of the medial group of the sole, in addition to the actions indicated in the names, are involved in strengthening the arch of the foot on its medial side.

b) Muscles lateral group are among two:

1. M. abductor digiti minimi, muscle that abducts the little toe of the foot, lies along the lateral edge of the sole, more superficial than other muscles. It starts from the calcaneus and attaches to the base of the proximal phalanx of the little finger.

2. M. flexor digiti minimi brevis, short flexor of the little toe, starts from the base of the fifth metatarsal bone and attaches to the base of the proximal phalanx of the little finger.

Function the muscles of the lateral group of the sole in the sense of the impact of each of them on the little finger is insignificant. Their main role is to strengthen the lateral edge of the arch of the foot. (Inn. of all three muscles 5i_n. N. plantaris lateralis.)

V) Middle group muscles:

1. M. flexor digitorum brevis, short flexor of the fingers, lies superficially under the plantar aponeurosis. It starts from the calcaneal tubercle and is divided into four flat tendons, attached to the middle phalanges of the II-V fingers.

Before their attachment, the tendons are each split into two legs, between which the tendons m. flexor digitorum longus. The muscle fastens the arch of the foot in the longitudinal direction and bends the toes (II-V). (Inn. L5-S2. N. plantaris medialis.)

2. M. quadrdtus plantae (m. flexor accessorius), quadratus plantae muscle, lies under the previous muscle, starts from the calcaneus and then joins the lateral edge of the tendon m. flexor digitorum longus. This bundle regulates the action of the flexor digitorum longus, giving its thrust a direct direction in relation to the fingers. (Inn. 51-2, N. plantaris lateralis.)

3. Mm. lumbricales, worm-shaped muscles, number four. As on the hand, they arise from the four tendons of the flexor digitorum longus and attach to the medial edge of the proximal phalanx of the II-V fingers. They can flex the proximal phalanges; their extension effect on other phalanges is very weak or completely absent.

They can also pull the other four fingers towards the big toe. (Inn. L5-S2. Nn. plantares lateralis et medialis.)

4. Mm. interossei, interosseous muscles, lie deepest on the side of the sole, corresponding to the spaces between the metatarsal bones. Dividing, like the corresponding muscles of the hand, into two groups - three plantar, mm. interossei plantares, and four dorsal, mm. interossei dorsdles, they at the same time differ in their location.

In the hand, due to its grasping function, they are grouped around the third finger; in the foot, due to its supporting role, they are grouped around the second finger, i.e. in relation to the second metatarsal bone. Functions: adduct and spread the fingers, but to a very limited extent. (Inn. 5i_n. N. plantaris lateralis.)

This group of foot muscles includes the muscles located in the middle of the sole. It consists of the following muscles: short flexor digitorum (m. flexor digitorum brevis), quadratus plantae (m. quadratus plantae), lumbrical muscles (mm. lumbricales), interosseous muscles (mm. interrossei).

Flexor digitorum brevis
M. flexor digitorum brevis

The most superficial muscle, lying under the plantar aponeurosis. It starts from the calcaneal tubercle and plantar aponeurosis. The muscle belly goes forward and passes into four flat tendons, attached to the middle phalanges of the II-V fingers.

Function:

flexion of the middle phalanges of the II-V fingers;
strengthening the arch of the foot.

Quadratus plantar muscle
M. quadratus plantae

It has a square shape, lies under the previous muscle. It starts with two heads from the back of the calcaneus, goes forward, attaches to the outer edge of the tendon of the long flexor of the fingers (m. flexor digitorum longus) to the point of its division into separate tendons.

The quadratus plantae muscle (m. quadratus plantae) is shown in Fig. 1.

Rice. 1. Muscles of the plantar surface of the foot (second level of the middle layer):

1 - quadratus plantae muscle (m. quadratus plantae);

2 - worm-shaped muscles (m. lumbricales).

Function:

regulates the action of the flexor digitorum longus.

Vermiform muscles
Mm. lumbricales

There are four thin and weak muscles. They originate from the corresponding tendon of the long flexor of the fingers (m. flexor digitorum longus) and are attached to the medial edge of the dorsal aponeurosis of the proximal phalanx of the II-V fingers.

Vermiform muscles (mm. lumbricales) are shown in Fig. 1.

Function:

flexion of the proximal phalanges of the II-V fingers, while simultaneously slightly extending their middle and distal phalanges.

Interosseous muscles
Mm. interossei

They lie deepest between the metatarsal bones. Represented by three plantar muscle bundles and four dorsal ones.

Interosseous muscles (mm. interossei) are shown in Fig. 2.

On the dorsum of the foot there are two small muscles, often fused at their origin: the extensor digitorum brevis and the extensor pollicis brevis muscle.

Extensor digitorum brevis (i.e. extensor digitorum brevis) lies under the tendons of the long extensor muscle. Starting from the anterior part of the calcaneus, the muscle is divided into four flat bellies, passing in front along with the tendons of the long extensor of the 1st – 4th fingers and the long extensor of the pollicis into the dorsal tendon extension on the phalanges of the 1st – 4th fingers. The muscle extends the fingers.

Muscles of the sole

The medial group is formed short muscles of the thumb - flexor, abductor And adductor(Fig. 1.58). The latter also strengthens the transverse arch of the foot.

The lateral group includes short muscles of the fifth finger.

The middle muscle group of the sole is the most developed, consisting of the short flexor digitorum, quadratus plantae, lumbrical and interosseous muscles of the foot.

Rice. 1.58. Muscles of the plantar side of the foot: 1 – worm-shaped;2 – flexor pollicis brevis;3 – flexor pollicis longus tendon;4 – abductor pollicis muscle;5 – plantar aponeurosis (cut off);6 – flexor digitorum brevis;7 – quadratus plantae muscle;8 – short muscles of the fifth finger;9 – peroneus longus tendon;10 – adductor pollicis muscle

Flexor digitorum brevis (t. flexor digitorum brevis), starting from the tubercle of the calcaneus and the plantar aponeurosis, it is divided into four abdomens (Fig. 1.58). The tendons of the latter, splitting into two legs, are attached to the lateral surfaces of the middle phalanges of the II–V fingers; The tendons of the flexor digitorum longus pass between the legs. The muscle flexes the toes and supports the longitudinal arch of the foot.

Quadratus plantar muscle (t. quadratus plantae) located under the flexor digitorum brevis (Fig. 1.58). It starts from the calcaneus and attaches to the lateral edge of the flexor digitorum longus tendon. The significance of the muscle comes down to establishing the longitudinal direction of thrust of the flexor digitorum longus, the tendon bundles of which approach the fingers obliquely.

Vermiform muscles of the foot (tt. lumbricales pedis) in the form of four weak muscle bundles, they begin from the four tendons of the flexor digitorum longus; distally, the muscles are attached to the medial edges of the main phalanges of the II–V fingers, partially passing into their dorsal tendon extension. The muscles flex the main phalanges, straightening the middle and nail ones.

Interosseous muscles of the foot (vt. interossei pedis) – four dorsal and three plantar, located in the intermetatarsal spaces. The muscles move the fingers along the sagittal axis, i.e. they are brought in and taken away.