Омыртқалы жануарлардың аяқ анатомиясы

Anatomical structure found in vertebrates
the anatomical structure

The foot (: feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.

The human foot has two longitudinal arches and a transverse arch maintained by the interlocking shapes of the foot bones, strong ligaments, and pulling muscles during activity. The slight mobility of these arches when weight is applied to and removed from the foot makes walking and running more economical in terms of energy. As can be examined in a footprint, the medial longitudinal arch curves above the ground. This arch stretches from the heel bone over the "keystone" ankle bone to the three medial metatarsals. In contrast, the lateral longitudinal arch is very low. With the cuboid serving as its keystone, it redistributes part of the weight to the calcaneus and the distal end of the fifth metatarsal. The two longitudinal arches serve as pillars for the transverse arch which run obliquely across the tarsometatarsal joints. Excessive strain on the tendons and ligaments of the feet can result in fallen arches or flat feet.

The muscles acting on the foot can be classified into extrinsic muscles, those originating on the anterior or posterior aspect of the lower leg, and intrinsic muscles, originating on the dorsal (top) or plantar (base) aspects of the foot.

All muscles originating on the lower leg except the popliteus muscle are attached to the bones of the foot. The tibia and fibula and the interosseous membrane separate these muscles into anterior and posterior groups, in their turn subdivided into subgroups and layers.

Extensor group: the tibialis anterior originates on the proximal half of the tibia and the interosseous membrane and is inserted near the tarsometatarsal joint of the first digit. In the non weight bearing leg, the tibialis anterior dorsiflexes the foot and lift its medial edge (supination). In the weight bearing leg, it brings the leg toward the back of the foot, like in rapid walking. The extensor digitorum longus arises on the lateral tibial condyle and along the fibula, and is inserted on the second to fifth digits and proximally on the fifth metatarsal. The extensor digitorum longus acts similar to the tibialis anterior except that it also dorsiflexes the digits. The extensor hallucis longus originates medially on the fibula and is inserted on the first digit. It dorsiflexes the big toe and also acts on the ankle in the unstressed leg. In the weight bearing leg, it acts similarly to the tibialis anterior. Peroneal group: the peroneus longus arises on the proximal aspect of the fibula and peroneus brevis below it. Together, their tendons pass behind the lateral malleolus. Distally, the peroneus longus crosses the plantar side of the foot to reach its insertion on the first tarsometatarsal joint, while the peroneus brevis reaches the proximal part of the fifth metatarsal. These two muscles are the strongest pronators and aid in plantar flexion. The peroneus longus also acts like a bowstring that braces the transverse arch of the foot.

The superficial layer of posterior leg muscles is formed by the triceps surae and the plantaris. The triceps surae consists of the soleus and the two heads of the gastrocnemius. The heads of gastrocnemius arise on the femur, proximal to the condyles, and the soleus arises on the proximal dorsal parts of the tibia and fibula. The tendons of these muscles merge to be inserted onto the calcaneus as the Achilles tendon. The plantaris originates on the femur proximal to the lateral head of the gastrocnemius and its long tendon is embedded medially into the Achilles tendon. The triceps surae is the primary plantar flexor. Its strength becomes most obvious during ballet dancing. It is fully activated only with the knee extended, because the gastrocnemius is shortened during flexion of the knee. During walking it not only lifts the heel, but also flexes the knee, assisted by the plantaris. In the deep layer of posterior muscles, the tibialis posterior arises proximally on the back of the interosseous membrane and adjoining bones, and divides into two parts in the sole of the foot to attach to the tarsus. In the non weight bearing leg, it produces plantar flexion and supination, and, in the weight bearing leg, it proximates the heel to the calf. The flexor hallucis longus arises on the back of the fibula on the lateral side, and its relatively thick muscle belly extends distally down to the flexor retinaculum where it passes over to the medial side to stretch across the sole to the distal phalanx of the first digit. The popliteus is also part of this group, but, with its oblique course across the back of the knee, does not act on the foot.

On the top of the foot, the tendons of extensor digitorum brevis and extensor hallucis brevis lie deep in the system of long extrinsic extensor tendons. They both arise on the calcaneus and extend into the dorsal aponeurosis of digits one to four, just beyond the penultimate joints. They act to dorsiflex the digits. Similar to the intrinsic muscles of the hand, there are three groups of muscles in the sole of foot, those of the first and last digits, and a central group:

Muscles of the big toe: the abductor hallucis stretches medially along the border of the sole, from the calcaneus to the first digit. Below its tendon, the tendons of the long flexors pass through the tarsal canal. The abductor hallucis is an abductor and a weak flexor, and also helps maintain the arch of the foot. The flexor hallucis brevis arises on the medial cuneiform bone and related ligaments and tendons. An important plantar flexor, it is crucial to ballet dancing. Both these muscles are inserted with two heads proximally and distally to the first metatarsophalangeal joint. The adductor hallucis is part of this group, though it originally formed a separate system (see contrahens). It has two heads, the oblique head originating obliquely across the central part of the midfoot, and the transverse head originating near the metatarsophalangeal joints of digits five to three. Both heads are inserted into the lateral sesamoid bone of the first digit. The adductor hallucis acts as a tensor of the plantar arches and also adducts the big toe and might plantar flex the proximal phalanx. Muscles of the little toe: Stretching laterally from the calcaneus to the proximal phalanx of the fifth digit, the abductor digiti minimi form the lateral margin of the foot and are the largest of the muscles of the fifth digit. Arising from the base of the fifth metatarsal, the flexor digiti minimi is inserted together with abductor on the first phalanx. Often absent, the opponens digiti minimi originates near the cuboid bone and is inserted on the fifth metatarsal bone. These three muscles act to support the arch of the foot and to plantar flex the fifth digit. Central muscle group: The four lumbricals arise on the medial side of the tendons of flexor digitorum longus and are inserted on the medial margins of the proximal phalanges. The quadratus plantae originates with two slips from the lateral and medial margins of the calcaneus and inserts into the lateral margin of the flexor digitorum tendon. It is also known as the flexor accessorius. The flexor digitorum brevis arises inferiorly on the calcaneus and its three tendons are inserted into the middle phalanges of digits two to four (sometimes also the fifth digit). These tendons divide before their insertions and the tendons of flexor digitorum longus pass through these divisions. Flexor digitorum brevis flexes the middle phalanges. It is occasionally absent. Between the toes, the dorsal and plantar interossei stretch from the metatarsals to the proximal phalanges of digits two to five. The plantar interossei adduct and the dorsal interossei abduct these digits, and are also plantar flexors at the metatarsophalangeal joints.

Humans usually wear shoes or similar footwear for protection from hazards when walking outside. There are a number of contexts where it is considered inappropriate to wear shoes. Some people consider it rude to wear shoes into a house and a Māori Marae should only be entered with bare feet. Foot fetishism is the most common sexual fetish.

A paw is the soft foot of a mammal, generally a quadruped, that has claws or nails (e. g., a cat or dog's paw). A hard foot is called a hoof. Depending on style of locomotion, animals can be classified as plantigrade (sole walking), digitigrade (toe walking), or unguligrade (nail walking). The metatarsals are the bones that make up the main part of the foot in humans, and part of the leg in large animals or paw in smaller animals. The number of metatarsals are directly related to the mode of locomotion with many larger animals having their digits reduced to two (elk, cow, sheep) or one (horse). The metatarsal bones of feet and paws are tightly grouped compared to, most notably, the human hand where the thumb metacarpal diverges from the rest of the metacarpus.

The word "foot" is used to refer to a " linear measure was in Old English (the exact length has varied over time), this being considered the length of a man's foot; a unit of measure used widely and anciently. In this sense the plural is often foot. The current inch and foot are implied from measurements in 12c." The word "foot" also has a musical meaning; a " metrical foot (late Old English, translating Latin pes, Greek pous in the same sense) is commonly taken to represent one rise and one fall of a foot: keeping time according to some, dancing according to others." The word "foot" was used in Middle English to mean "a person" (c. 1200). The expression " to put one's best foot foremost first recorded 1849 (Shakespeare has the better foot before, 1596)". The expression to " put one's foot in (one's) mouth "say something stupid" was first used in 1942. The expression "put (one's) foot in something" meaning to "make a mess of it" was used in 1823. The word "footloose" was first used in the 1690s, meaning "free to move the feet, unshackled"; the more "figurative sense of "free to act as one pleases" was first used in 1873. Like "footloose", "flat footed" at first had its obvious literal meaning (in 1600, it meant "with flat feet") but by 1912 it meant "unprepared" (U. S. baseball slang).