DORSUM OF FOOT

 DORSUM OF FOOT

•       The muscles of the dorsum of the foot are a group of two muscles, which together represent the dorsal foot musculature.They are named extensor digitorum brevis and extensor hallucis brevis.

•       muscles lie within a flat fascia on the dorsum of the foot (fascia dorsalis pedis) and are innervated by the deep fibular or peroneal nerve.

 

•       Extensor digitorum brevis

•       Origins: Superolateral surface of calcaneus bone

•       Insertions: Middle phalanges of toes 2-4

•       Innervation: Deep fibular/peroneal nerve (S1, S2)

•       Function: Distal interphalangeal joints 2-4: Toe extension

•       Extensor hallucis brevis

•       Origins: Superolateral surface of calcaneus bone

•       Insertions: Proximal phalanx of great toe

•       Innervation: Deep fibular/peroneal nerve (S1, S2)

•       Function: Metatarsophalangeal joint 1: Toe extension

 DORSALIS PEDIS ARTERY

•       Origin: It is the direct continuation of the anterior tibial artery.

•       Course: It begins midway between the 2 malleoli (at the ankle joint) superficial in position and is crossed by the inferior extensor retinaculum and the first tendon of extensor digitorum brevis.

 

•       Relations:

•       On its lateral side lie the terminal part of the deep peroneal nerve and the extensor digitorum longus tendons.

•        On the medial side lies the tendon of extensor hallucis longus. Its pulsations can easily be felt.

•       Termination by passing downward into the sole between the two heads of the first dorsal interosseous muscle, where it joins the lateral plantar artery and completes the plantar arch

•       The deep peroneal nerve (deep fibular nerve) begins at the bifurcation of the common peroneal nerve between the fibula and upper part of the peroneus longus, passes infero-medially, deep to extensor digitorum longus, to the anterior surface of the interosseous membrane, and comes into relation with the anterior tibial artery above the middle of the leg; it then descends with the artery to the front of the ankle-joint, where it divides into a lateral and a medial terminal branch.

 •       Medial terminal branch - This nerve accompanies the dorsalis pedis artery along the dorsum of the foot, and, at the first interosseous space, divides into two dorsal digital nerves which supply the adjacent sides of the great and second toes,communicating with the medial dorsal cutaneous branch of the superficial peroneal nerve. Before it divides it gives off to the first space an interosseous branch which supplies the metatarsophalangeal joint of the great toe and sends a filament to the first Interosseous dorsalis muscle.

•       Lateral terminal branch - This nerve passes across the tarsus, beneath the extensor digitorum brevis, and supplies the extensor digitorum brevis. This nerve ends in a pseudoganglion deep to the extensor digitorum brevis. From the pseudoganglion, three minute branches are given off to supply the tarsal joints and the metatarsophalangeal joints of the second, third, and fourth toes.

 

DORSAL FASCIA OF FOOT

•       It is the continuation of the deep fascia of the leg (crural fascia).

•       Apart from the muscles of the dorsum of the foot, it incloses the tendons of the anterior muscles of the leg, dorsalis pedis vessels (continuation of the anterior tibial artery) and branches of the deep peroneal nerve. In contrast the dorsal venous network (rete venosum dorsale pedis) lies above the fascia and is easily visible due to the relatively thin and low-fat skin.