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We will not describe the metatarsophalangeal and interphalangeal joints here, because they are identical to the joints of the fingers of the hand, with the exception of some functional differences. So, in the metacarpophalangeal joints, the amplitude of flexion is greater than the extension, and in the metatarsophalangeal joints, on the contrary, the extension exceeds the flexion:

• the amplitude of active extension in the metatarsophalangeal joints ranges from 50° to 60°, and flexion is only 30–40°;
• the amplitude of passive extension (Fig. 72), which plays a significant role in the last phase of the step, reaches 90 ° and may even exceed this figure, while passive flexion remains within 45-50 °.

Lateral movements of the toesoccur in the metatarsophalangeal joints within much smaller limits than the corresponding movements of the fingers. The big toe of the human foot, as opposed to thumb monkeys, lost the function of opposition as a result of the transition to movement on two legs.

Active toe extensionIt is provided by three muscles: two external ones - the long extensor of the thumb and the long extensor of the fingers - and one internal muscle of the foot - the short extensor of the fingers.

Short finger extensor(Fig. 73) is located completely on the back of the foot. It originates from the calcaneal floor of the tarsal sinus and from the trunk of the lower retinaculum of the extensor tendons, divides into four fleshy bellies, which are attached by tendons to the outer sides of the corresponding tendons of the long extensor of the fingers, with the exception of the tendon belonging to the first metatarsal bone, which is attached directly to dorsal surface of the first phalanx of the thumb; the fifth finger does not receive any tendon from this muscle at all. Thus, the short extensor of the toes is the extensor of the metatarsophalangeal joints of the first four fingers (Fig. 74).

Long extensor toes and extensor thumb longuslocated in the anterior case of the lower leg, their tendons end at the phalanges.

extensor toe longus tendon(Fig. 75) passes anterior to the ankle joint, deeper than the outer half of the upper retinaculum of the extensor tendons, then posterior to the trunk of the lower retinaculum, after which it is divided into four tendons going to the II-V fingers, passing under the lower plate of the anterior annular ligament. Therefore, the V finger is unbent only due to the action of the common long extensor. This muscle, as its name implies, is an extensor of the toes, but in addition, it serves, very importantly, as a flexor of the ankle joint. Its extensor action on the fingers is only seen in its purest form when its function as an ankle flexor is balanced by an antagonist extensor (mainly the triceps, shown as white arrow). The tendon of the long extensor of the first finger (Fig. 76) passes deeper than the upper retinaculum of the tendons of the extensor muscles and then penetrates both legs of the lower retinaculum. It is attached to the back surface of both phalanges of the thumb: along the edges of the rear of the first phalanx and to the back surface of the base of the distal phalanx. Therefore, this muscle is not only the extensor of the thumb, but also, no less important, the flexor of the ankle joint. As with the extensor digitorum longus, its thumb extension action only occurs after its function as an ankle flexor is balanced by its antagonist. Duchenne de Boulogne states that the extensor digitorum brevis is the only true extensor.


"lower limb. Functional Anatomy"
A.I. Kapanji

The dorsal muscles are at the top of the foot (Fig. 10.39). The interosseous muscles, which occupy the space between the metatarsal bones, are also referred to as the dorsal muscles, since they are very easy to reach from the top of the foot. It is quite easy to treat the dorsal and interosseous muscles. Pain from trigger points in them is local in nature and is not transmitted to other places.

Extensors brevis and interosseus muscles

Short extensors fingers lie under the long extensor tendons at the top of the foot. Both extensor groups work together to lift your toes off the ground with every step you take.

Between the metatarsal bones there are two groups of interosseous muscles - dorsal and plantar. The third group of small muscles are worm-like - parallel to the metatarsal on the sole, but not located between them. The interosseous muscles allow the fingers to move from side to side and are involved in their flexion and extension. This mass of small muscles may seem like very little, but they play a big role in maintaining the balance of the body and adapting the feet to the ground. Their function is to restrain excess movements of the larger, but less sensitive muscles in the foot.

Symptoms

Pain from trigger points in the short extensors occurs immediately aroundthese muscles, which are located on top of the foot on her outside(Fig. 1 0.39). In the figure, the extensor of four fingers consists of three heads of muscles adjacent to the four fingers. The extensor pollicis brevis is the only muscle that goes to the thumb.

Their common area of ​​pain distribution coincides with the area of ​​its distribution from long extensor of the fingers, anterior tibial and third peroneal muscles. Sometimes you have to explore all of these muscles to find trigger points that cause pain. One woman would have suffered with legs for the rest of her life if she had not caught the eye of some new information.

Pain from trigger points in the interosseous musclesfelt at the base of the toes, often extending to the tips of the toes (fig. 10.40). In some cases, the pain covers the entire back of the foot and goes up to the front of the lower leg (not shown). Trigger points in the interosseous muscles often cause cramps and swelling on the dorsum of the foot. A dull aching pain at the top of the foot can come from any dorsal plantar muscle. Trigger points in the first dorsal interosseous muscle can cause tingling in the thumb. In any of the zones, there is more numbness than pain.

The reasons

Walking, running, or climbing too frequently and vigorously can contribute to the formation of trigger points in any of the interosseous muscles or in any of the extensor muscles.
It is not uncommon for all of these muscles to have points, as they all depend on each other in this delicately balanced system of footwork. Be careful if the shoes are tight at the top of the foot. Tight shoes interfere with circulation and movement by creating problems with the interosseous muscles and extensor digitorum brevis. It's good to ditch high heels, because they cause the legs to roll towards the toes and all the muscles gather in front of the feet. On the other hand, if you are not used to walking barefoot, this can also negatively affect the muscles, causing them to strain unnecessarily.

Treatment

Locate the short toe extensor muscles by their contraction as you lift your toes (Fig. 1 0.41). To massage the dorsal muscles, use only your fingertips or a weighted thumb.
These muscles are usually small and thin and do not require much pressure. To massage the interosseous muscles, dip the tips of two fingers or the thumb into the space between the metatarsal bones, above or below them (Fig. 10.42). Figures 10.43 and 10.44 show two other methods for interosseous massage. When the interosseous trigger points are active, it can cause a lot of pain and even trigger cramps if you push too hard. If, in an attempt to cope with a cramp in the arch of the foot, you begin to stretch it, cramps can occur in the interosseous muscles and in the short extensors at the top of the foot. If you are used to stretching your foot, pre-massage will reduce the risk.

Provide mobility to the foot different muscles, including the short extensor of the big toe, as well as other short and long muscles. Short muscles do not leave the area of ​​​​the foot itself and are attached within it. The long muscles have their base in the lower leg and are attached to the foot. Thanks to the short and long muscles, extension of both the big and other toes occurs. The foot performs the most important shock-absorbing and stabilizing function. The main movements that the foot makes are flexion and extension.

foot anatomy

The muscles of the foot, according to their position, are divided into dorsal (or dorsal) and plantar. In addition, they can be lateral and medial. If a conditional median line is drawn through the human body, then those areas that are closer to this line are called medial. The areas closer to the outer edge are called lateral. The human foot can move in many directions. There are such types of limb movement:

• flexion/extension;
• abduction / adduction;
• pronation/supination.

The phalanges of the toes are also quite mobile. This is necessary to perform a stabilizing function and maintain balance. Their mobility is provided by a short extensor of the fingers and a separate muscle related to the thumb. The extensor digitorum brevis is a rather wide and flat muscle that runs along the entire outer region of the foot. It is attached to the calcaneus, then goes to the phalanges, where it branches into 3 tendons. In the upper part, these tendons are combined with the extensor tendon of the thumb and are attached to the phalanges. This muscle is powered by the tibial artery, and innervated by the peroneal nerve.

On the plantar side, there are muscles of their own, thanks to which the movement of the phalanges and the foot as a whole becomes possible. These include the muscles that abduct and bend the phalanges on the legs, as well as the worm-shaped and square muscles.

Long muscles of the feet

The muscles involved in flexion and extension of the phalanges can also be long. At one end they are attached to the bones of the lower leg, and at the other - to the phalanges on the legs. long flexor fingers attached to the tibia. Combining with the square muscle, the long flexor is divided into 4 tendons, which are attached directly to the phalanges. Due to the fact that the long flexor of the fingers is attached to four phalanges at the same time, not only flexion movements become possible, but also movement in different directions.

There is also a separate muscle that is responsible for flexion thumbs on the foot. The long flexor of the big toe is attached at one end to the lower part of the fibula, and at the other end to the base of the big toe. The long flexor of the big toe is the most powerful muscle on the back of the leg. In addition to ensuring the movement of the phalanx, it is needed to maintain the arch of the foot. Also, the long flexor of the fingers is also necessary in order to bend the second and third phalanges, since its tendon is partially associated with the tendons of these fingers. In addition to flexion and extension of the foot, the flexor hallucis longus is also required for supination and adduction.

Responsible for the extension of the phalanges on the legs long muscles. The extensor digitorum longus is located on the outer side of the lower leg and is attached to a bone called the tibia. Then the long extensor of the fingers stretches along the lower leg and in the foot diverges into 5 branches, which are attached to the phalanges with the help of tendons. The long extensor of the fingers is involved not only in their extension, but also in the extension of the limb.

extensor hallucis longus

The extensor hallucis longus originates at the bottom of the fibula. It is attached to the base of the bones of the thumbs. The long extensor of the thumb is necessary not only for the movement of himself, but also for the mobility of the limb.

The extensor pollicis longus also provides supination and circular motions feet.

How to strengthen your feet

Strengthening these structures is essential for our health. There is such a thing as "the core of the legs." It includes small muscles needed to stabilize the entire body. Thanks to them, shocks are softened when running and walking, and a stable body position is maintained. If these muscles are weakened, then the entire load will be distributed on the plantar fascia, which is fraught with the development of plantar fasciitis. Moreover, a weak ligamentous-muscular apparatus leads to a gradual change in gait, which can cause problems with the knees, hip joints and even with the spine.

To strengthen the foot, there are simple exercises that you can do at home.

Complex	Performance
Exercise number 1.	You will need a towel for this exercise. Grab it with your toes and stretch it around the room. Having reached the opposite wall of the room, with your feet form a lump out of this towel. Then grab the fabric again and drag it to the other end of the room. Do this exercise with each foot.
Exercise number 2.	This exercise is performed while sitting. To complete it, you will need small items (for example, glass balls, dice, buttons). Grab an object from one pile with your feet and transfer it to another. Do the same with the other foot.
Exercise number 3.	The exercise can be done while sitting. Over time, it is performed standing on one leg. Place your foot on the floor in the normal position. Then pull your fingers towards you, forming an arch with the arch of the foot.
Exercise number 4.	Sit on the floor with your legs extended straight out in front of you. Tighten the foot and arch it as if it were wearing shoes on high heels. Lock the leg in such a tense position and slowly turn the foot towards you.

The positive effect of such home exercises occurs after 3-4 months. The main thing is not the duration of the exercises, but their regularity. After a few months, the muscles of the feet will strengthen, the arch will rise. It will also improve blood circulation, increase the sensitivity of the foot, which is extremely important for developing stability.

Walk barefoot more often on grass, sand and pebbles, after making sure that there are no foreign objects.

Pay special attention to the health of the legs. Fatigue and heaviness in the legs may be the first signs that not everything is in order with the legs. To prevent the development of many unpleasant diseases, it is necessary to adhere to some preventive recommendations.

1. Avoid the "wrong" shoes. Start by throwing away your slippers. If barefoot is uncomfortable for you, you can buy thick sports socks. When choosing shoes for everyday wear, pay attention to the quality of shoes and the manufacturer. Make sure that it has a fairly tight (but not "wooden" backdrop). It is good if the insoles are in shoes with special insoles or liners.
2. if you have overweight then you have to get rid of them. The fact is that excess weight creates an additional and constant load on the feet, as a result of which they seem to “spread” and sag. This can lead to the development of flat feet.
3. To strengthen the muscles of the lower leg and feet, use a jump rope. If you have no contraindications, jump rope will help not only make your muscles stronger, but also increase the overall endurance of the body. In addition, when jumping, plaques on the walls of blood vessels are destroyed, which has an additional positive effect.
4. get busy general strengthening organism. For this, hardening, sunbathing and walking barefoot on grass or sand are suitable. Do not forget also about taking vitamin complexes, especially in the autumn-winter period.

Combination simple exercises and recommendations has a significant positive effect on the entire body. Do not neglect these recommendations and remember that the regularity and consistency of their implementation is the key to your health.

The long flexor thumb is located deep under the calf and soleus muscles and
covers the posterior tibial muscle. The muscle is located laterally on the back surface
shins. The belly muscle attaches to the posterior surface of the fibula, joining the tibialis posterior and flexor digitorum longus just behind the medial malleolus.

These muscles pass through the tarsal canal, formed by the medial surface of the calcaneus and the fibrous plate of the flexor tendon retinaculum. In structure and function, this structure is identical to the carpal tunnel. The tibial artery and tibial nerve also pass through the tarsal canal.

The flexor hallucis longus, flexor digitorum longus, and tibialis posterior produce inversion of the foot and plantarflexion of the ankle. In addition, the flexor thumb longus flexes the thumb at the metatarsophalangeal and interphalangeal joints. This movement is necessary in the take-off phase of walking for efficient energy transfer. The center of gravity shifts from the heel through the foot to the big toe at the end of the stance phase and the energy generated by the hips, knees and shins passes through the foot and big toe, moving the human body forward.

The flexor hallucis longus plays a significant role in directing this energy. In addition, the long flexor of the big toe is involved in providing dynamic stabilization of the medial arch of the foot. Together with other muscles passing through the tarsal canal and the muscles of the foot, the flexor hallucis longus controls the pronation of the foot during walking, running and jumping. The long flexor of the big toe provides effective grip of the foot with the surface and helps us to effectively maintain balance when walking.

Problems with this muscle can flatten the medial arch of the foot and destabilize the ankle, resulting in pain, loss of sensation, and gait disturbance when walking.

Palpation of the long flexor of the big toe

The client lies on his stomach

1. Standing at the client's feet, use your thumb to locate the medial malleolus.

2. In a smooth sliding motion, slide your thumb into the space between your ankle and Achilles tendon. (Caution: the tibial artery and nerve also pass through this area. Move your finger if the client feels tingling and numb, and if you feel a pulse.)

3. There are three tendons in this area. Palpate the tendon located most
is the tendon of the long flexor of the big toe.

4. Ask the client to bend their thumb to make sure you did everything right.

CLIENT EXERCISE: SEATED TOE STRETCH

1. Sit on the floor with your feet straight in front of you.

2. With your knees relaxed, bend at the waist and lean forward.

3. Take the big toe with your fingers.

4. Gently pull your thumb back towards your knee for 5-10 seconds, then release.

This exercise can be done with all toes.

In terms of location, action and number, the muscles of the toes are almost similar to the muscles of the fingers of the hand, but, as already indicated, depending on the little developed activity of the toes, the muscles of the rear of the foot are more related to movement in the ankle joint, and the muscles of the plantar side are involved in strengthening the arch of the foot.

Extensors and flexors of the toes

Between the extensors of the fingers (dorsal flexors) and their flexors (plantar flexors) we find long and short extensors, as well as long and short flexors. The first are located on the front surface of the lower leg and on the back of the foot, the second - on the back surface of the lower leg and on the sole.

Among the extensors we have the extensor digitorum longus and the extensor hallucis longus, which have already been described above; it remains for us to disassemble only the short extensors of the fingers.

Short finger extensor(m. extensor digitorum brevis, Fig. 72-11) begins on the dorsum of the calcaneus; its innermost part stands out under the name of the short extensor of the thumb (m. extensor hallucis brevis, Fig. 72-22). At the level of the metatarsal bones, the muscle fibers pass into the tendons of the first four fingers. All of them obliquely fit (outside inwards) to the outer side of the tendons of the long extensor and merge with them at the base of the first phalanx, except for the tendons of the thumb. The tendon of the short extensor of the thumb is attached directly to the first phalanx.

The short extensor of the fingers mainly acts on the first phalanges. The oblique arrangement of its tendons allows the abduction of the fingers outward in the metatarsophalangeal joint. Acting simultaneously with the long extensor of the fingers, the short extensor produces pure extension of the fingers at the metatarsophalangeal joint. The tendon of the short extensor of the first finger, attaching directly to the first phalanx, produces its extension.

Innervation: deep peroneal nerve (n. peroneus profundus, L IV-V and S I).

Among the flexors of the fingers, there are: a long flexor of the thumb and a common long flexor of the fingers with an accessory head starting from the calcaneus, a square muscle of the sole and a short common flexor of the fingers. In addition, there is a short flexor for both the thumb and little finger.

flexor digitorum longus(m. flexor digitorum communis longus, Fig. 66-7) is located in the deepest layer of the lower leg. It starts from two-thirds of the posterior surface of the tibia, in addition, part of its fibers originate from the tendon arch formed by the fascia. tibialis muscle.

So start it muscle fibers reaches the fibula. The posterior tibial muscle, approaching the formed tendon of the long flexor, crosses it and is located directly near the inner ankle. The tendon of the long flexor of the fingers, going down, is located closer to middle line shins and goes to the sole. On the sole, it receives a tendon stalk from the long flexor of the thumb and, in addition, from the lower and inner surface heel bone, a short additional head is attached to it - square muscle soles(m. quadratus plantae, s. sago quadrata Sylvii, Fig. 66-23). Then, at the level of the base of the metatarsal bones, the common tendon of the long common flexor of the fingers splits into four bundles, which immediately give rise to the so-called vermiform muscles, which extend from the inner (from the side of the first finger) side of its tendons. Moving further forward, each tendon of the common long flexor lies in a canal formed by the bifurcation of the corresponding tendon of the short flexor, just as it was on the hand of the superficial and deep flexors of the fingers. Located together with the short common flexor "of the fingers in the bone-fibrous sheath of the fingers, the tendons of the long flexor end, attaching to the third (nail) phalanges of the fingers -

The long common flexor of the fingers flexes the third phalanges over the second and the second over the first; at the maximum of its contraction, it can somewhat bend the first phalanx over the metatarsal bone; in addition, it informs the IV and V fingers of some deviation inwards, which is especially evident in the position of their nail phalanges. This last action is explained by the oblique (inside outward) direction of the tendons of the IV and V fingers on the sole. If the action of its accessory head and the action of the short common finger flexor are added to the action of the general long flexor of the fingers, then this deviation is destroyed.

Duchenne and Poirier completely deny the action of the long common flexor of the fingers on the ankle joint during the upper support. Braus, on the other hand, believes that with the upper support, the common long flexor of the fingers can produce plantar flexion, supination (turning the sole inside) and abduction medially (from the midline of the foot), with supination being most pronounced, plantar flexion being the least, and abduction medially corresponding to the action posterior tibial muscle. When a person is in a standing position, the long flexor of the fingers strengthens the arches of the foot and can extend the lower leg (plantar flexion) when raising the torso on toes.

Innervation: tibial nerve (n. tibialis, L V and S I).

Short common finger flexor(m. flexor digitorum communis brevis, Fig. 74) starts from the lower surface of the calcaneal tubercle, from the posterior third of the upper surface of the plantar aponeurosis and from the intermuscular septa. At the level of the base of the metatarsal bones, it forms four tendons, which split longitudinally at the level of the first phalanges and, having passed the corresponding tendons of the long

the common flexor of the fingers, pass through the bone-fibrous sheath and are attached to the sides of the second phalanges, reaching their articulations with the third. Their attitude and construction are quite consistent with the attitude and construction of the superficial and deep flexor of the fingers, which were described above. The tendon of the flexor of the fifth finger is sometimes very thin and is not pierced by the tendon of the common long flexor of the fingers, sometimes it is completely absent.

The short common flexor of the fingers flexes the second (phalanges) and almost does not show 4 its action on either the first or third phalanges. With a lower support, its main action is to strengthen the longitudinal arch of the foot (Fig. 74) and plantar aponeurosis.

Innervation: plantar internal nerve (n. plan-taris medialis, L V and S I).

flexor thumb longus(m. flexor hallucis longus, Fig. 66-19, 15) is the most external muscle deep posterior muscle layer of the lower leg; it begins on the middle lower third of the posterior surface of the fibula; going down and inside, it passes into the tendon, located in the groove located on the posterior surface of the talus, fits under the internal process of the calcaneus (sustentaculum tali) and goes to the inner edge of the foot.

On this path, the tendon of the long flexor of the thumb crosses with the tendon of the long common flexor of the fingers, connects to it with a tendon bundle and then, passing between both parts of the short flexor of the thumb and both sesamoid bones of the metacarpophalangeal joint of the thumb, reaches its nail phalanx, where it attached (Fig. 74-4).

The long flexor thumb strongly flexes the second phalanx and has little effect on the metatarsophalangeal joint. Duchenne completely rejects its influence on the ankle joint. According to Braus, the flexor hallucis longus plays a large role in pushing the foot off the ground. It is also necessary to note its importance in relation to the movements of the entire foot. It is predominantly a plantar flexor, but at the same time, with the upper support, it abducts the foot inwards and supinates it. With lower support, the long flexor of the big toe strengthens the arch of the foot in the longitudinal direction and counteracts the formation of a flat sole (pes planum).

Innervation: tibial nerve (n. tibialis, L V and S I-II).

Flexor thumb short(m. flexor hallucis brevis, Fig. 74-2; 75-1) is divided into two parts. Both of its parts start from the sphenoid bones, from the ligamentous apparatus connecting the plantar surface of the calcaneus and metatarsal bones, and from the plantar aponeurosis. Heading towards the thumb along the metacarpal bone, the short flexor of the thumb is divided into two parts and attached to the tubercle of the first phalanx: one on the outside, the other on the inside. Both tendons have sesamoid ossicles.

Rice. 75. deep muscles feet. (Poirier.) 1 - short flexor of the thumb, 2 - transverse head of the adductor thumb muscle, 2 "- oblique head of the adductor thumb muscle, 3 - short flexor of the V finger, 4 - muscle opposing the V finger, 5 - tendon of the long peroneal muscle - its course along the plantar surface and attachment

The short flexor thumb flexes the thumb at the metatarsophalangeal joint, which is especially important when standing on toes. Acting with separate heads, the short flexor of the thumb can abduct the first phalanx to one side and the other (from the midline of the foot). Starting from the deep ligamentous apparatus of the foot and to the side of the plantar aponeurosis, it strengthens the internal longitudinal arch of the foot along with other muscles.

Fifth finger flexor short(m. flexor digiti quinti, Fig. 75-3) starts from the fibrous sheath of the long peroneal muscle, from the crest of the lower surface of the cuboid bone, from the base of the metatarsal bone of the fifth finger and is attached to the base of the first phalanx of the fifth finger. It flexes the V finger at the metatarsophalangeal joint, and also strengthens the outer longitudinal arch of the foot through the plantar aponeurosis.

Innervation: external plantar nerve (n. plantaris lateralis, S I-II).

Muscles that abduct the toes to kick three and outward from the midline of the foot

Abduction, which is possible in the metatarsophalangeal joints, is performed in the same way as on the hand, by means of the interosseous and vermiform muscles, and in the thumb and small fingers, also by specially abducting muscles. Only the opposing muscle of the thumb is missing here; as for the same muscle of the fifth finger, it is sometimes observed. On the foot, as well as on the hand, in this group there should be 10 abductor and adductor muscles. Of these, the muscles that abduct and adduct the thumb, as well as the abductor of the thumb, are located on the sole, and the rest are between the metatarsal bones, which is why they, like the muscles of the hand, are called interosseous. The worm-like muscles, which were mentioned in the description of the long common flexor of the fingers, being located on the inside of its tendons, also take part in the abduction of the II finger and the adduction of the III, IV and V fingers.

On the foot, the middle line, towards which adduction (adductio) will be performed and away from which abduction (abductio) will be performed, coincides with the middle line of the second finger. Thus, only the second finger will have two interosseous muscles that abduct to both sides of the midline, while the remaining fingers will have interosseous muscles that abduct from the midline and lead to it.

At the thumb, we have an independent muscle that abducts the thumb and an independent adductor.

Abductor thumb muscle(m. abductor hallucis, Fig. 74-3) lies superficially under the fascia on the inner edge of the foot and forms an elevation of the thumb. The abductor muscle starts directly from the lower part of the inner surface of the calcaneal tubercle, as well as from the ligamentous apparatus of the foot and plantar aponeurosis; it is attached by a well-developed tendon to the inner edge of the first phalanx, fusing with the tendon of the inner head of the short flexor of the thumb. Sometimes the abductor thumb muscle sends a tendon extension to the extensor tendon of the thumb. It produces the abduction of the thumb from the midline of the foot, in which it is partly helped by the inner head of the short flexor of the thumb.

The muscle that abducts the thumb can be attributed to a static type: pinnate arrangement of fibers (powerful tendon). Its main value is to strengthen the inner arch of the foot. Abduction of the thumb is weakly expressed.

Innervation: internal plantar nerve (n. plantaris medialis, L V and S I).

adductor thumb muscle(m. adductor hallucis, Fig. 75-2, 2 ") consists of two heads. One of them, obliquely located, starts from the cuboid bone, from the third sphenoid, second and third metatarsal bones, and also from the fibrous sheath of the long peroneal muscle and goes obliquely from the middle of the foot to the first finger.The second head, transversely located, starts from the head of the metatarsal bone of the fourth finger and, on the way to the first finger, crosses the heads of all other metacarpal bones in the transverse direction, receiving separate muscle bundles from them and from the intermetatarsal ligaments.

The obliquely located head, approaching the first finger, fuses with the outer head of the short flexor of the thumb and together with it will bring the thumb to the midline of the foot. The transversely located head of the adductor thumb muscle is more independent than was observed on the hand, and some (Lebuk) even indicate that this muscle has an independent attachment on the first phalanx: on the one hand, it sends a continuation to the rear of the thumb to its extensor , on the other hand, part of the fibers, passing through the attachment of the oblique head of the adductor muscle of the thumb and its short flexor, ends at the bone-fibrous sheath of the thumb. The oblique head has the strongest adductor effect on the first phalanx of the big toe and, as Duchene points out, is an active ligament that does not allow the heads of the metatarsal bones to diverge, and thus strengthens the transverse arch of the foot.

Innervation: internal and external plantar nerves (n. n. plantares medialis et lateralis, S I-II).

Abductor fifth finger muscle(m. abductor digiti quinti, Fig. 74-5), like the muscle that removes the thumb, is located superficially, but only on the outside. The muscle abducting the V finger begins from the lower surface of the posterior external tubercle of the calcaneus, from the inwardly facing surface of the plantar aponeurosis and from the intermuscular septum that separates it from the short flexor of the fingers. Heading forward along the metacarpal bone of the fifth finger, it ends in outer surface the base of the first phalanx of the fifth finger and on the lower surface of the marsupial ligament of the metatarsophalangeal joint.

In most cases, the muscle that abducts the V finger is only a flexor of the first phalanx, and only in children can it still be abducted. Being located on the outside from the heel to the main phalanx of the fifth finger, it, of course, has a great influence on strengthening the outer arch.

Innervation: external plantar nerve (b. plantaris lateralis, S I-II).

The abduction and adduction of the remaining fingers is performed with the help of the interosseous muscles; they are located like the interosseous muscles of the hand, on the one hand, in the deepest layer on the sole (interosseous internal muscles), on the other hand, on the back of the foot (interosseous external muscles). As on the hand, there are three internal interosseous muscles on the foot, four on the outside; the inner ones will lead to the midline of the foot, the outer ones will lead away from the midline; you just need to remember that the midline of the foot passes through the second toe and therefore two abductors will be at the second toe, and not at the third, as we saw on the hand.

Adductor internal interosseous muscles(m. m. interossei interni, Fig. 76) start from the posterior third of the lower edge of each of the last three metacarpal bones (V, IV and III) and from the lower surface of their base. They lie more superficial than the interosseous spaces themselves, so that they completely cover the lower surface of the metacarpal bones. They end in a completely different way than the internal interosseous muscles of the hand: in most cases, they are attached only to the lateral internal (on the side of the thumb) part of the first phalanx and to the bursal ligament of its joint; they do not continue to the extensor tendon of the fingers.

According to their location and attachment, the internal interosseous muscles are the muscles leading to the midline of the foot III, IV and V fingers; the second finger has no adductor muscle, since it lies on the midline of the foot, and the big one has its own adductor, described above (Fig. 75-2).

Innervation: deep branches of the external plantar nerve (rami profundi n. plantaris lateralis, S I-II).

Abductor external interosseous muscles(m. m. interossei externi, Fig. 77) are located on the back of the foot, fulfilling all the gaps between the metacarpal bones. They are biceps and start from the lateral parts of the metacarpal bones facing each other, from the lower surface of their bases and the dorsal interosseous fascia. Starting from two opposite sides, they form pennate muscles, the tendons of which are attached to the base of the first phalanges and to the bursal ligament of the joint on the outside of the III and IV fingers and on both sides of the II finger. They do not continue to the extensor tendon of the fingers; rather, you can find continuations to the cartilaginous thickenings of the bag of the metatarsophalangeal joint.

The interosseous muscles of the IV, III and II fingers are abducting from the midline of the foot. These movements in the foot are very limited, as they are constantly constrained by shoes, and are most marked in children or people who do not wear shoes. Approaching the first phalanx from both sides, more from the plantar surface, and combining its action with the action of the internal interosseous muscles, the external interosseous muscles of the IV, III and II fingers bend the first phalanx; the same movement is produced by the abductor V finger in combination with the internal interosseous V finger.

Innervation: deep branches of the external plantar nerve (n. plantaris lateralis, S I-II).

vermiform muscles(m. m. lumbricales,) mentioned above when describing the long common flexor of the fingers, from the tendons of which they begin, also take part in the abduction of the fingers. Located on inside of each tendon of the II, III, IV and V fingers, they are attached to the inside of the first phalanges of the same fingers, and, therefore, will contribute to the work of the interosseous muscles that produce abduction in their direction. In the second finger, they will produce abduction from the midline, and in the remaining (III, IV and V) fingers, they will lead to the midline.

The vermiform muscles, to a certain extent, can participate in the flexion of the first phalanges.

Innervation: internal plantar nerve (n. plantaris medialis); external plantar nerve (n. plantaris lateralis to the first, third and fourth, L V and S I-II).

To the muscles of the foot, one must also add a non-permanent muscle that opposes the fifth finger.

Opposite V finger muscle(m. opponens digiti quinti, Fig. 75-4). Man does not have an opposing muscle of the thumb, since the thumb, being one of the main points of support, has lost all significance for grasping. The opposing muscle of the fifth finger is important for adapting the sole to uneven ground. Even when it exists, it is poorly developed and not completely separable from the flexor brevis and abductor digit V. It differs from the muscles mentioned only in that it is attached not to the first, but to the metacarpal bone of the fifth finger. During its contraction, the muscle opposing the V finger pulls the metacarpal bone somewhat inward (towards the midline of the foot) downwards.