Extensor Hallucis Longus Muscle – Anatomy, Nerve Supply

Blood Supply of Extensor Hallucis Longus Muscle

The anterior tibial artery supplies the extensor hallucis longus muscle. The anterior tibial artery arises from the popliteal artery, which originates from the superficial femoral artery, a branch of the common femoral artery off of the external iliac artery. As the superficial femoral artery passes through the adductor hiatus into the popliteal fossa, it becomes the popliteal artery. The popliteal artery then divides toward the distal end of the popliteal fossa to give rise to the anterior and posterior tibial arteries. The anterior tibial artery passes from the posterior popliteal fossa to the anterior leg through the interosseous membrane between the tibia and fibula. It continues down the anterior portion of the leg to supply all of the muscles of the anterior compartment including the extensor hallucis longus before terminating as the dorsalis pedis artery as it passes into the foot.

The lymphatic vessels of the lower limb divide into two major groups—superficial and deep vessels. The superficial lymph vessels of the lower limb further subdivide into two groups: a medial group, which follows the greater saphenous vein, and a lateral group, which follows the small saphenous vein. There are also deep lymph vessels including the anterior tibial, posterior tibial and peroneal vessels that follow the course of the corresponding arteries and veins. The lymph vessels of the lower limb drain into the popliteal, superficial inguinal, deep inguinal, external iliac and lumbar? or aortic lymph nodes.

Nerves Supply of Extensor Hallucis Longus Muscle

The tibial nerve, composed of spinal roots L4, L5, S1, S2, and S3, innervates the flexor hallucis longus; it receives the majority of its nerve supply from the S1 and S2, but also receives innervation from L5 as well via the muscular branch of the tibial nerve.[rx]

The deep peroneal nerve innervates the extensor hallucis longus. The deep peroneal nerve is one of the terminal branches of the common peroneal nerve, which originates from the sciatic nerve. The sciatic nerve branches at the apex of the popliteal fossa into the tibial and common peroneal nerves. The tibial nerve continues its course down the leg, posterior to the tibia supplying the deep muscles of the posterior leg. It terminates by dividing into two sensory branches, medial and lateral plantar nerves.[rx] The common peroneal artery follows the medial border of the biceps femoris, running in a lateral and inferior direction continuing over the head of the gastrocnemius.[rx] The common peroneal nerve wraps around the neck of the fibula passing between the attachments of the fibularis longus muscle to supply the lateral compartment of the leg.[rx] It then divides and terminates into the superficial peroneal, which will supply the lateral compartment of the leg and the deep peroneal which will supply the anterior compartment of the leg including the extensor hallucis longus.[rx] The nerve roots of the deep peroneal artery are L4 to S1. Injury to the deep peroneal nerve can result in foot drop and consequently gait difficulty and a characteristic high step gait.

Functions of Extensor Hallucis Longus Muscle

The primary action of the extensor digitorum longus is to extend the lateral four toes at the metatarsophalangeal joint. This means that when acting independently, it is unable to extend the entire length of the toes, extending only at metatarsophalangeal, while at the interphalangeal joints the toes remain flexed. However, contracting together with lubricants which are the main extensors of the interphalangeal joints, this muscle contributes to extension at every joint between the bones of the lateral four toes.

Acting in synergy with tibialis anterior, extensor hallucis longus and fibularis tertius, this muscle participates in dorsiflexion of the foot when their proximal attachments are fixed. When the distal attachments are fixed and the body is in the anatomical position, all four muscles bring the trunk and lower limb to the front. This action moves the body weight-bearing point from the proximal to the distal part of the foot.

All of these actions are important for the gait cycle; the dorsiflexion angulates and lifts the foot above the walking surface, while the toe extension keeps the toes extended until the heel hits the ground.