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The foot (: feet) is an anatomical structure found in many . It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is an organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.
The foot can be subdivided into the hindfoot, the midfoot, and the forefoot:
The hindfoot is composed of the talus bone (or ankle bone) and the calcaneus (or heel bone). The two long bones of the lower leg, the tibia and fibula, are connected to the top of the talus to form the ankle. Connected to the talus at the subtalar joint, the calcaneus, the largest bone of the foot, is cushioned underneath by a layer of fat.
The five irregular bones of the midfoot, the cuboid bone, navicular bone, and three cuneiform bones, form the arches of the foot which serve as a shock absorber. The midfoot is connected to the hind- and fore-foot by muscles and the plantar fascia.
The forefoot is composed of five and the corresponding five proximal long bones forming the metatarsus. Similar to the fingers of the hand, the bones of the toes are called phalanx bone and the big toe has two phalanges while the other four toes have three phalanges each. The joints between the phalanges are called interphalangeal and those between the metatarsus and phalanges are called metatarsophalangeal (MTP).
Both the midfoot and forefoot constitute the dorsum (the area facing upward while standing) and the planum (the area facing downward while standing).
The instep is the arched part of the top of the foot between the toes and the ankle.
There can be many near the metatarsophalangeal joints, although they are only regularly present in the distal portion of the first metatarsal bone.Platzer 2004, p. 220
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.Platzer 2004, p. 260
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 muscle is also part of this group, but, with its oblique course across the back of the knee, does not act on the foot.Platzer 2004, p. 264
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 tunnel. 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.Platzer 2004, pp. 270–72
Muscles of the fifth 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.Platzer 2004, p. 272
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.Platzer 2004, p. 274
This leaves humans more vulnerable to medical problems that are caused by poor leg and foot alignments. Also, the wearing of shoes, sneakers and boots can impede proper alignment and movement within the ankle and foot. For example, are known to throw off the neutral spine (this can also affect the lower back). For the sake of posture, flat soles with no heels are advised.
A physician who specializes in the treatment of the feet practices podiatry and is called a podiatrist. A pedorthist specializes in the use and modification of footwear to treat problems related to the lower limbs.
Bone fracture of the foot include:
This rolling inward motion as the foot progresses from heel to toe is the way that the body naturally absorbs shock. Neutral pronation is the most ideal, efficient type of gait when using a heel strike gait; in a forefoot strike, the body absorbs shock instead via flexion of the foot.
An overpronator does not absorb shock efficiently. Imagine someone jumping onto a diving board, but the board is so flimsy that when it is struck, it bends and allows the person to plunge straight down into the water instead of back into the air. Similarly, an overpronator's arches will collapse, or the ankles will roll inward (or a combination of the two) as they cycle through the gait. An individual whose bone structure involves external rotation at the hip, knee, or ankle will be more likely to overpronate than one whose bone structure has internal rotation or central alignment. An individual who overpronates tends to wear down their running shoes on the medial (inside) side of the shoe toward the toe area.
When choosing a running or walking shoe, a person with overpronation can choose shoes that have good inside support—usually by strong material at the inside sole and arch of the shoe. It is usually visible. The inside support area is marked by strong greyish material to support the weight when a person lands on the outside foot and then roll onto the inside foot.
Like an overpronator, an underpronator does not absorb shock efficiently, but for the opposite reason. The underpronated foot is like a diving board that, instead of failing to spring someone in the air because it is too flimsy, fails to do so because it is too rigid. There is virtually no give. An underpronator's arches or ankles do not experience much motion as they cycle through the gait. An individual whose bone structure involves internal rotation at the hip, knee, or ankle will be more likely to underpronate than one whose bone structure has external rotation or central alignment. Usually – but not always – those who are bow-legged tend to underpronate. An individual who underpronates tends to wear down their running shoes on the lateral (outside) side of the shoe toward the rear of the shoe in the heel area.
Foot fetishism is the most common sexual fetish.
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.France 2008, p. 537
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 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).
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