Editing Human leg (section)

==== Lower leg and foot ====
{| class="wikitable" style="float:right; margin-left:15px"
|+ Function of foot muscles<ref name="Platzer-266">Platzer (2004), p. 266</ref>
|-
! Movement !! Muscles<br />(in order of<br />importance)
|-
|Dorsi-<br />flexion
|
•Tibialis anterior<br />•Extensor digitorum<br />longus<br />•Extensor hallucis<br />longus
|-
|Plantar<br />flexion
|
•Triceps surae<br />•[[Fibularis longus|Fibularis (peroneus) longus]]<br />•[[Fibularis brevis|Fibularis (peroneus) brevis]]<br />•Flexor digitorum<br />longus<br />•Tibialis posterior
|-
|[[Eversion (kinesiology)|Eversion]]
|
•Fibularis (peroneus) longus<br />•Fibularis (peroneus) brevis<br />•Extensor digitorum<br />longus<br />•[[Fibularis tertius|Fibularis (peroneus) tertius]]
|-
|Inversion
|
•Triceps surae<br />•Tibialis posterior<br />•Flexor hallucis<br />longus<br />•Flexor digitorum<br />longus<br />•Tibialis anterior
|}
With the [[Popliteus muscle|popliteus]] (see above) as the single exception, all muscles in the leg are attached to the foot and, based on location, can be classified into an anterior and a posterior group separated from each other by the tibia, the fibula, and the [[Interosseous membrane of the leg|interosseous membrane]]. In turn, these two groups can be subdivided into subgroups or layers—the anterior group consists of the extensors and the peroneals, and the posterior group of a superficial and a deep layer. Functionally, the muscles of the leg are either extensors, responsible for the [[dorsiflexion]] of the foot, or flexors, responsible for the [[plantar flexion]]. These muscles can also classified by innervation, muscles supplied by the [[Common fibular nerve|anterior subdivision]] of the plexus and those supplied by the [[Tibial nerve|posterior subdivision]].<ref>Platzer (2004), p. 256</ref> The leg muscles acting on the foot are called the extrinsic foot muscles whilst the foot muscles located ''in'' the foot are called intrinsic.<ref name=Starkey2015>{{Cite book|last1=Starkey|first1=Chad|last2=Brown|first2=Sara|url=https://www.fadavis.com/product/athletic-training-examination-orthopedic-athletic-injuries-starkey-brown-4|title=Examination of Orthopedic & Athletic Injuries|publisher=[[F. A. Davis Company]]|year=2015|isbn=978-0-8036-4503-5|edition=4|page=175|language=en|chapter=8 - Foot and Toe Pathologies}}</ref>

Dorsiflexion (extension) and plantar flexion occur around the transverse axis running through the ankle joint from the tip of the medial malleolus to the tip of the lateral malleolus. Pronation (eversion) and supination (inversion) occur along the oblique axis of the ankle joint.<ref name="Platzer-266" />

===== Extrinsic =====
[[File:Gray437.png|thumb|left|upright=0.55|Anterior muscles]]

Three of the anterior muscles are extensors. From its origin on the lateral surface of the tibia and the interosseus membrane, the three-sided belly of the [[Tibialis anterior muscle|tibialis anterior]] extends down below the [[Superior extensor retinaculum of foot|superior]] and [[Inferior extensor retinaculum of foot|inferior extensor retinacula]] to its insertion on the plantar side of the [[medial cuneiform bone]] and the first [[metatarsal bone]]. In the non-weight-bearing leg, the anterior tibialis dorsal flexes the foot and lifts the medial edge of the foot. In the weight-bearing leg, it pulls the leg towards the foot. The [[Extensor digitorum longus muscle|extensor digitorum longus]] has a wide origin stretching from the lateral condyle of the tibia down along the anterior side of the fibula, and the interosseus membrane. At the ankle, the tendon divides into four that stretch across the foot to the dorsal [[aponeuroses]] of the last phalanges of the four lateral toes. In the non-weight-bearing leg, the muscle extends the digits and dorsiflexes the foot, and in the weight-bearing leg acts similar to the tibialis anterior. The [[Extensor hallucis longus muscle|extensor hallucis longus]] has its origin on the fibula and the interosseus membrane between the two other extensors and is, similarly to the extensor digitorum, is inserted on the last phalanx of big toe ("hallux"). The muscle dorsiflexes the hallux, and acts similar to the tibialis anterior in the weight-bearing leg.<ref>Platzer (2004), p. 258</ref> Two muscles on the lateral side of the leg form the fibular (peroneal) group. The [[fibularis longus|fibularis (peroneus) longus]] and [[fibularis brevis|fibularis (peroneus) brevis]] both have their origins on the fibula, and they both pass behind the [[lateral malleolus]] where their tendons pass under the [[fibular retinacula]]. Under the foot, the fibularis longus stretches from the lateral to the medial side in a groove, thus bracing the [[transverse arch of the foot]]. The fibularis brevis is attached on the lateral side to the tuberosity of the fifth metatarsal. Together, these two [[fibularis muscles]] form the strongest pronators of the foot.<ref>Platzer (2004), p. 260</ref> The fibularis muscles are highly variable, and several variants can occasionally be present.<ref>Chaitow (2000), p. 554</ref>

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Of the posterior muscles three are in the superficial layer. The major plantar flexors, commonly referred to as the [[triceps surae]], are the [[Soleus muscle|soleus]], which arises on the proximal side of both leg bones, and the [[Gastrocnemius muscle|gastrocnemius]], the two heads of which arises on the distal end of the femur. These muscles unite in a large terminal tendon, the [[Achilles tendon]], which is attached to the posterior tubercle of the [[calcaneus]]. The [[Plantaris muscle|plantaris]] closely follows the lateral head of the gastrocnemius. Its tendon runs between those of the soleus and gastrocnemius and is embedded in the medial end of the calcaneus tendon.<ref>Platzer (2004), p. 262</ref>

In the deep layer, the [[Tibialis posterior muscle|tibialis posterior]] has its origin on the interosseus membrane and the neighbouring bone areas and runs down behind the [[medial malleolus]]. Under the foot it splits into a thick medial part attached to the [[navicular bone]] and a slightly weaker lateral part inserted to the three cuneiform bones. The muscle produces simultaneous plantar flexion and supination in the non-weight-bearing leg, and approximates the heel to the calf of the leg. The [[Flexor hallucis longus muscle|flexor hallucis longus]] arises distally on the fibula and on the interosseus membrane from where its relatively thick muscle belly extends far distally. Its tendon extends beneath the [[flexor retinaculum of foot|flexor retinaculum]] to the sole of the foot and finally attaches on the base of the last phalanx of the hallux. It plantarflexes the hallux and assists in supination. The [[Flexor digitorum longus muscle|flexor digitorum longus]], finally, has its origin on the upper part of the tibia. Its tendon runs to the sole of the foot where it forks into four terminal tendon attached to the last phalanges of the four lateral toes. It crosses the tendon of the tibialis posterior distally on the tibia, and the tendon of the flexor hallucis longus in the sole. Distally to its division, the [[Quadratus plantae muscle|quadratus plantae]] radiates into it and near the middle phalanges its tendons penetrate the tendons of the [[Flexor digitorum brevis muscle|flexor digitorum brevis]]. In the non-weight-bearing leg, it plantar flexes the toes and foot and supinates. In the weight-bearing leg it supports the [[plantar arch]].<ref name="Platzer 2004, p 264" /> (For the [[Popliteus muscle|popliteus]], see above.)

===== Intrinsic =====
The intrinsic muscles of the foot, muscles whose bellies are located in the foot proper, are either dorsal (top) or plantar (sole).
On the dorsal side, two long extrinsic extensor muscles are superficial to the intrinsic muscles, and their tendons form the dorsal aponeurosis of the toes. The short intrinsic extensors and the plantar and dorsal interossei radiates into these aponeuroses. The [[Extensor digitorum brevis muscle|extensor digitorum brevis]] and [[Extensor hallucis brevis muscle|extensor hallucis brevis]] have a common origin on the anterior side of the calcaneus, from where their tendons extend into the dorsal aponeuroses of digits 1–4. They act to dorsiflex these digits.<ref>Platzer (2004), p. 268</ref>

The plantar muscles can be subdivided into three groups associated with three regions: those of the big digit, the little digit, and the region between these two. All these muscles are covered by the thick and dense [[plantar aponeurosis]], which together with two tough septa, form the spaces of the three groups. These muscles and their fatty tissue function as cushions that transmit the weight of the body downward. As a whole, the foot is a functional entity.<ref name="Platzer-270">Platzer (2004), p. 270</ref>

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The [[Abductor hallucis muscle|abductor hallucis]] stretches along the medial edge of the foot, from the calcaneus to the base of the first phalanx of the first digit and the medial sesamoid bone. It is an abductor and a weak flexor, and also helps maintain the arch of the foot. Lateral to the abductor hallucis is the [[Flexor hallucis brevis muscle|flexor hallucis brevis]], which originates from the medial cuneiform bone and from the tendon of the tibialis posterior. The flexor hallucis has a medial and a lateral head inserted laterally to the abductor hallucis. It is an important plantar flexor which comes into prominent use in [[classical ballet]] (i.e. for [[en pointe|pointe work]]).<ref name="Platzer-270" /> The [[Adductor hallucis muscle|adductor hallucis]] has two heads; a stronger oblique head which arises from the cuboid and lateral cuneiform bones and the bases of the second and third metatarsals; and a transverse head which arises from the distal ends of the third-fifth metatarsals. Both heads are inserted on the lateral sesamoid bone of the first digit. The muscle acts as a tensor to the arches of the foot, but can also adduct the first digit and plantar flex its first phalanx.<ref name="Platzer-272">Platzer (2004), p. 272</ref>

The [[Opponens digiti minimi muscle|opponens digiti minimi]] originates from the long plantar ligament and the plantar tendinous sheath of the fibularis (peroneus) longus and is inserted on the fifth metatarsal. When present, it acts to plantar flex the fifth digit and supports the plantar arch. The [[Flexor digiti quinti brevis muscle (foot)|flexor digiti minimi]] arises from the region of base of the fifth metatarsal and is inserted onto the base of the first phalanx of the fifth digit where it is usually merged with the abductor of the first digit. It acts to plantar flex the last digit. The largest and longest muscles of the little toe is the [[Abductor digiti quinti muscle (foot)|abductor digiti minimi]]. Stretching from the lateral process of the calcaneus, with a second attachment on the base of the fifth metatarsal, to the base of the fifth digit's first phalanx, the muscle forms the lateral edge of the sole. Except for supporting the arch, it plantar flexes the little toe and also acts as an abductor.<ref name="Platzer-272" />

The four [[Lumbrical muscle (foot)|lumbricales]] have their origin on the tendons of the flexor digitorum longus, from where they extend to the medial side of the bases of the first phalanx of digits two-five. Except for reinforcing the plantar arch, they contribute to plantar flexion and move the four digits toward the big toe. They are, in contrast to the lumbricales of the hand, rather variable, sometimes absent and sometimes more than four are present. The [[quadratus plantae]] arises with two slips from margins of the plantar surface of the calcaneus and is inserted into the tendon(s) of the flexor digitorum longus, and is known as the "plantar head" of this latter muscle. The three [[Plantar interossei muscles|plantar interossei]] arise with their single heads on the medial side of the third-fifth metatarsals and are inserted on the bases of the first phalanges of these digits. The two heads of the four [[Dorsal interossei muscles (foot)|dorsal interossei]] arise on two adjacent metatarsals and merge in the intermediary spaces. Their distal attachment is on the bases of the proximal phalanges of the second-fourth digits. The interossei are organized with the second digit as a longitudinal axis; the plantars act as adductors and pull digits 3–5 towards the second digit; while the dorsals act as abductors. Additionally, the interossei act as plantar flexors at the [[metatarsophalangeal joint]]s. Lastly, the [[Flexor digitorum brevis muscle|flexor digitorum brevis]] arises from underneath the calcaneus to insert its tendons on the middle phalanges of digit 2–4. Because the tendons of the flexor digitorum longus run between these tendons, the brevis is sometimes called ''perforatus''. The tendons of these two muscles are surrounded by a tendinous sheath. The brevis acts to plantar flex the middle phalanges.<ref>Platzer (2004), p. 274</ref>
{{See also|Table_of_muscles#Leg|l1=Table of muscles}}