Användare:Tanzania/översättningar/arkiverad/7

Fotens muskler kan delas in i yttre muskler, de som sitter på den främre eller bakre delen av underbenet, och inre muskler, på ovan- eller undersidan av foten.

Alla muskler som sitter på underbenet, förutom popliteusmuskeln, är fästa på fotens ben. Skenbenet och vadbenet, samt de intraossala membranen delar upp musklerna i främre och bakre grupper, som i sin tur är uppdelade i undergrupper och lager.^[1]

Tibialis sitter på den proximala delen av skenbenet och de intraossala membranen och är infogad i den delen av stortån som är närmast tåvalken. I det ej viktbärande benet spänner tibialis foten dorsalt och lyfter dess mediala kant (supination). I det viktbärande benet tar det benet mot fotens baksida, likt i snabbt gångtempo. Extensor hallucis longus sitter medialt på adbenet och är infogat i den första tån. Såsom namnet antyder dorsiflexas stortån och agerar även på vristen i det obetonade benet. I det viktbärande benet agerar det likt främre skenbensmuskeln (tibialis anterior).^[2]

Peroneal group: peroneus longus arises on the proximal aspect of the fibula and peroneus brevis below it on the same bone. Together, their tendons pass behind the lateral malleolus. Distally, peroneus longus crosses the plantar side of the foot to reach its insertion on the first tarsometatarsal joint, while peroneus brevis reaches the proximal part of the fifth metatarsal. These two muscles are the strongest pronators and aid in plantar flexion. Longus also acts like a bowstring that braces the transverse arch of the foot. ^[3]

Deep and superficial layers of posterior leg muscles

Posterior group

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 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. 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 and its strength becomes most obvious during ballet dancing. It is fully activated only with the knee extended because the gastrocnemius is shortened during knee flexion. During walking it not only lifts the heel, but also flexes the knee, assisted by the plantaris. ^[4]

In the deep layer of posterior muscles 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. flexor hallucis longus arises on the back of the fibula (i.e. 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. ^[5]

On the back (top) of the foot, the tendons of extensor digitorum brevis and extensor hallucis brevis lie deep to 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. ^[6]

Mall:Triple image

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: 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. It is an abductor and a weak flexor, and also helps maintain the arch of the foot. flexor hallucis brevis arises on the medial cuneiform bone and related ligaments and tendons. An important plantar flexor, it is crucial for ballet dancing. Both these muscles are inserted with two heads proximally and distally to the first metatarsophalangeal joint. 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. Adductor hallucis acts as a tensor of the plantar arches and also adducts the big toe and then might plantar flex the proximal phalanx. ^[7]

Muscles of the little toe: Stretching laterally from the calcaneus to the proximal phalanx of the fifth digit, abductor digiti minimi form the lateral margin of the foot and is the largest of the muscles of the fifth digit. Arising from the base of the fifth metatarsal, flexor digiti minimi is inserted together with abductor on the first phalanx. Often absent, 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. ^[8]

Central muscles of foot

Central muscle group: The four lumbricales arise on the medial side of the tendons of flexor digitorum longus and are inserted on the medial margins of the proximal phalanges. 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 flexor accessorius. Flexor digitorum brevis arise 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 adducts and the dorsal interossei abducts these digits and are also plantar flexors at the metatarsophalangeal joints. ^[9]