The tibialis anterior muscle is a muscle of the anterior compartment of the lower leg. It originates from the upper portion of the tibia; it inserts into the medial cuneiform and first metatarsal bones of the foot. It acts to dorsiflex and invert the foot. This muscle is mostly located near the shin.
It is situated on the lateral side of the tibia; it is thick and fleshy above, tendinous below. The tibialis anterior overlaps the anterior tibial vessels and deep peroneal nerve in the upper part of the leg.
The tibialis anterior muscle is innervated by the deep fibular nerve, and recurrent genicular nerve (L4).[2]
Variation
A deep portion of the muscle is rarely inserted into the talus, or a tendinous slip may pass to the head of the first metatarsal bone or the base of the first phalanx of the great toe.[citation needed]
The muscle acts to dorsiflex and invert the foot.[2] It is the largest dorsiflexor of the foot.[1] The muscle also contributes to deceleration.[4][better source needed]
Function
The muscle helps maintain the medial longitudinal arch of the foot.[2] It draws up and holds the toe in a locked position. The tibialis anterior aids in any activity that requires moving the leg or keeping the leg vertical. It functions to stabilize the ankle as the foot hits the ground during the contact phase of walking (eccentric contraction) and acts later to pull the foot clear of the ground during the swing phase (concentric contraction). It also functions to 'lock' the ankle, as in toe-kicking a ball, when held in an isometric contraction.[5][better source needed]
The movements of tibialis anterior are dorsiflexion and inversion of the ankle. However, actions of tibialis anterior are dependent on whether the foot is weight bearing or not (closed or open kinetic chain). When the foot is on the ground, the muscle helps to balance the leg and talus on the other tarsal bones so that the leg is kept vertical even when walking on uneven ground.[citation needed]
Clinical significance
A tibialis anterior hernia is a rare type of hernia in which fat or other material protrudes through a defect in the tibialis anterior muscle.[6] It may be caused by trauma, such as an inadvertent kick to the lower leg from an opposing player in a football match.[citation needed]
Additional images
medial view of dissected ankle has two muscles
Lateral aspect of right leg.
Tibialis anterior muscle
Cross-section through top third and second third of right leg.
Tibialis anterior muscle
Ankle joint. Deep dissection. Lateral view *This has some structures labelled incorrectly e.g. tibialis anterior, extensor hallucis longus and cuboid bone
