Anatomy of the foot

introduction

The differences between humans and four-legged friends are most pronounced on the feet. In contrast to many four-legged friends, for a normal, secure stance, humans need a foot that rests on the ground with 2 or 3 points.

The foot is connected to the lower extremity via ankle joints. A distinction is made between the upper ankle joint (OSG) and the lower ankle joint (USG). The upper ankle joint has the important task of rolling the foot. The lower ankle, on the other hand, is responsible for better adaptation to sloping and uneven terrain. The toes also serve this purpose, with which it is also possible to “claw in”. Shock absorption takes place via the anatomical arch construction of the foot, which consists of several bones.

Ultimately, it can be said that the mobility of the foot is made possible by the upper and lower ankle. Ankle joints as such are joints that are fixed or secured by ligaments.

Foot bones

The foot (Pes) consists of a total of 26 bonesthat are in 3 different areas let divide:

• the tarsusTarsus (tarsus)

• the metatarsus (Metatarsus)

• the forefoot (Antetarsus)

Tarsus

The Tarsus can now be further subdivided:

Ankle bone (Talus):

The talus or talus has the so-called "bone body" on it. Trochlea or joint roller. It forms the important one Articulation of the upper ankle joint with the malleolar fork, an ankle fork or joint fork for the upper ankle joint.

Immediately behind the joint roller is the Processus posterior tali, the bone process of the talus. in the lower ankle however, the joint surfaces are formed by the Talar head together with the Scaphoid (Navicular bone).

Heel bone (Calcaneus):

The calcaneus forms the largest and longest bones of the foot skeleton. The basic shape of the calcaneus is cube-shaped and therefore has 6 surfaces. It lies with that Calcaneal tuberosity on the ground and is at the same time on the Formation of the lower ankle involved.

The tendon of the runs under a horizontal protrusion of bone on the heel bone in a groove Flexor hallucis longus muscle. The real function of the calcaneus is its property as Lever arm for the flexor muscles in the lower leg. Another important role played by this bone in fractures (breaks). Jumps from great heights often lead to fractures of this bone, which usually always have to be treated surgically.

Scaphoid (Navicular bone):

Put simply, it is Scaphoid nothing more than a kind Bone slicethat lies between the head of the talus and the three cuneiform bones. These are called as follows:

• Medial cuneiform bone

• Ossa cuneiformia intermedium

• Ossa cuneiformia laterale

The wedge shape of these bones is largely responsible for the anatomical transverse arching of the foot. They form joints with the so-called Ossa metatarsi 1, 2 & 3. These form the bony basis of the metatarsus.

Cuboid bone (Os cuboideum):

The cuboid bone is a pyramidal bone belonging to the tarsal family. It is between the 4th / 5th Metatarsal bones and the above Heel bone.

Joint formations occur at the lateral front end of the calcaneus and the Ossa metatarsi 4 & 5 come about. There is also a groove on the underside of the bone in which the tendon of the Peroneus longus muscle runs.

You can find further information under our topic: Tarsus.

Metatarsus

The Metatarsal bones (Metatarsal bone 1-5) together form the Metatarsus. A distinction is made between the bones themselves Base, shaft and one spherical heads.

The latter then forms a joint with the base of the toes. Of the Os metatarsi 1 is the thickest and at the same time the shortest metatarsal bone. Due to the high load, the Os metatarsi 5 the second thickest.

Forefoot (antetarsus)

The toes, too Digiti called, form the forefoot. Systemic numbering is also carried out here. This is how you distinguish Digitus pedis 1-5, where the Digitus pedis 1 the big toe (Hallux) and the Digitus pedis V represents the little toe.

The structure of toes 2-5 is the same. They each consist of a base phalanx, a middle phalanx and a distal toe phalanx. Just like the hand, the big toe consists of only 2 toe links or phalanges. Due to their lower mobility, the toe skeleton is regressed compared to the fingers of the hand.

Joints of the foot

Tarsal joints

With the exception of the ankle joints, all tarsal joints are amphiarthroses, i.e. "real" joints that have a joint space:

• Articulatio calcaneocuboidea

• Articulatio tarsi transversa (Chopart joint line)

This is where the talus and calcaneus are separated from the tarsal bones further forward:

• Articulatio cuneonavicularis

• Articulatio cuneocuboidea

• Articulationes intercuneiformes

Joints of the metatarsals

Tight joints bind the Metatarsus or his bone strong on:

• Articulationes tarsometatarsales: Tarsal metatarsal joints, which are reinforced by tight ligaments, are severely restricted in their freedom of movement. Only the two outer tarsometatarsal joints have slightly more freedom of movement.

• Articlationes intermetatarsales: This is a "real" joint between the bases of the 2nd-5th Metatarsal bones. This joint is also secured by tight ligaments and therefore restricted in its mobility.

Toe joints

The toe joints are what are known as Diathrosis, so "fake joints":

• Articulationes metatarsophalangea: Metatarsophalangeal joints between metatarsus and toes. From a functional point of view, these are ball joints with 2 degrees of freedom or movement.

• Articulationes interphalangea pedis: These joints are located between the middle and end joints of the toes. This type of joint is (functionally) a hinge joint.

Tape apparatus

Similar to the hand, the ligamentous apparatus is complex and consists of many strong, collagenous ligaments. Ligaments from the medial malleolus form a kind of collagen-fibrous plate (Deltoid ligament) and consist of the following 4 parts and are called the central collateral ligament:

• Pars tibiotalaris posterior

• Pars tibiocalcanea

• Pars tibiotalaris anterior

• Pars tibionavicularis

They all have a common origin at the inwardly facing malleolar fork, a protruding bone at the lower end of the tibia. Together with the lateral malleolar fork of the fibula, it encompasses the ankle bone in a fork shape.

The beginnings of the ligaments are on the ankle bone, the scaphoid bone and the heel bone, with 2 of them (Pars tibiocalcanea & Pars tibionavicularis) even have an additional effect on the lower ankle.

The function of these ligaments is of great importance for the mechanics of the foot. All four ligaments prevent valgization of the foot. This is a valgus position, i.e. a joint position in which the joint is bent laterally inward. A well-known example is the knock knees position in the knee. In addition, it inhibits pronation in the lower ankle joint, which corresponds to an elevation of the lateral edge of the foot while simultaneously lowering the inner edge of the foot.

The 3 lateral collateral ligaments that start from the outer ankle are called as follows:

• Posterior talofibular ligament

• Calcaneofibular ligament

• Talofibular anterior ligament

As already mentioned, the 3 bands also have a common origin. Their approaches are in each case on the bony process and neck of the ankle bone, as well as on the heel bone. The Calcaneofibular ligament is the only ligament that has an effect on the lower ankle.

Short foot muscles

The meaning of short foot muscles limited to that Tension of the arch of the foot.

There is also a clear structure here:

• Big toe box

• Little toe box

• Middle muscle box

However, it should be said that the arrangement as well as the supply by the annoy similar to the hand is.

Short muscles of the back of the foot

A distinction is made between the Extensor hallucis brevis muscle and the Extensor digitorum brevis muscle. Both have their origin on the upward facing surface of the calcaneus. This thin, but broad muscle pulls across the back of the foot and puts his tendon on the front Big toe on. Of the Deep fibular nerve from the spinal cord segment L5-S1 supplies this area. Both muscles function in the Extension of the big toe towards the back of the foot or the Extension of the 2nd-4th toe.

Short foot muscles of the sole of the foot

Muscles of the big toe box:

• Abductor hallucis muscle: It has several origins with its fibers. On the one hand on the bone process of the calcaneus and on the other hand on the scaphoid bone and a stiff tendon plate on the lower surface of the foot (plantar fascia). The nerves are supplied by the Medial plantar nerve from the spinal cord segment S1, S2. Its function is to bend and splay the big toe.

• Flexor hallucis brevis muscle: It is a two-headed muscle with origins on the inner side of the cuboid and the sphenoid. It also has a fibrous origin on the extension of the posterior tibial muscle (M. tibialis posterior). Both heads attach their sinewy ends to the central or lateral sesamoid bone. The function is limited to the flexion of the big toe.

• Adductor hallucis muscle: It's a two-headed muscle. With his Caput transversum it arises at the third to fifth metatarsophalangeal joint. The Caput obliquum arises from the cuboid bone, the outer sphenoid bone and the Ossa metatarsi 2-4 and lies in the middle box of the sole of the foot. The common tendon runs along the lateral sesamoid bone and attaches to the base of the big toe. The nerve stimulation is supplied via the Lateral plantar nerve from the segment S1, S2. Its function is to attach and flex the big toe.

Muscles of the little toe box:

• Abductor digiti minimi muscle

• Flexor digiti minimi brevis muscle

• Opponens digiti minimi muscle

Of the Lateral plantar nerve supplies all three muscles when a nerve is stimulated.

There is also no difference in function for any of the three muscles. They all result in an abortion and flexion of the little toe. However, their origins are different. So has the Abductor minimi muscle originates from the above-mentioned tendon plate, while the other two muscles are located on the 5th metatarsal (Os metatarsi 5) have their origin. Of the M. abducor digiti minimi, as well as the M. flexor digiti minimi brevis have their beginnings on the front phalanx of the little toe. Only the M. opponens digiti minimi starts at the back of the 5th metatarsal.

Muscles of the central box:

• Musculus flexor digitorum brevis: The origin lies on the tendon plate of the sole of the foot and on the heel hump of the calcaneus. Its approach is on the middle links of the 2nd-5th Toe. Here too, nerve stimuli are transmitted through the Medial plantar nerve from the spinal cord segment S1, S2. It causes the toe to flex in the metacarpophalangeal joint.

• Quadratus plantae muscle: The calcaneus serves as the origin for this muscle. Its approach is to the tendons of the Flexorum digitorum longus muscle. Of the Lateral plantar nerve supplies this muscle. Here, too, the function is to flex the toes. It also increases the effect of the Flexor digitorum longus muscle in the ankle.

• Musculii lumbricales: These are four muscles that originate from the tendons of the Flexor digitorum longus muscle to have. The attachments of these muscles extend on the front extremities of the 2nd-5th centuries. Toe. Here, too, the nerve stimuli are transmitted through the N. plantaris. However, both through its middle and outer part. All four muscles support the flexion of the toes in the base joint.

• Musculii interossei dorsales 1-4: The origin is at the metatarsal bones 1-5. Its approaches are on the front part of the end links 2-4. The toes 2-4 are spread apart by the Lateral plantar nerve conveyed.

• Musculii interossei plantares: Here, too, there are three muscles. They all have their origin in the metatarsal bones 3-5 and also start at the front part of the terminal phalanges of the toes 3-5. Of the Lateral plantar nerve causes toes 3-5 to attach to toe 2.