Overview

Tibialis anterior arises from the lateral condyle and the upper half of the lateral surface of the tibia and the interosseous membrane. Its tendon begins in the lower third of the leg, passes under the superior and inferior extensor retinacula (the most medial tendon there), and inserts on the medial and plantar surfaces of the medial cuneiform and the base of the 1st metatarsal.

It dorsiflexes the ankle and inverts the foot. In gait, it lifts the foot clear of the ground during swing. At heel strike it lowers the forefoot under control by eccentric contraction, preventing "foot slap". It also helps support the medial longitudinal arch. It is supplied by the deep fibular nerve (L4–L5), and the anterior tibial artery runs beside it on the interosseous membrane. Its tendon is easily seen and felt in front of the ankle when the foot is dorsiflexed and inverted.

Location: Anterior compartment of the leg, lateral to the tibia.

Anatomy

Origin: Lateral condyle and the upper half of the lateral surface of the tibia; interosseous membrane.
Insertion: Medial and inferior surfaces of the medial cuneiform and the base of the 1st metatarsal.
Action: Dorsiflexion of the ankle and inversion of the foot.
Innervation: Deep fibular (peroneal) nerve.
Nerve roots: L4–L5
Arterial supply: Anterior tibial artery.
Relations: The anterior tibial vessels and the deep fibular nerve lie lateral to it, between it and EHL/EDL. It is subcutaneous along the shin.

Function

Dorsiflexes the ankle
Inverts the foot
Controls lowering of the foot after heel strike; supports the medial arch

Clinical significance

Foot drop

Lesions of the deep or common fibular nerve (fibular neck fracture, compression), L4–L5 radiculopathy or anterior compartment syndrome weaken dorsiflexion. Patients develop a high-stepping (steppage) gait with the foot slapping down. Treated with an ankle–foot orthosis.

Anterior compartment syndrome and shin splints

Swelling within the tight anterior compartment (after tibial fracture or exertion) causes pain on passive plantarflexion and numbness in the first web space (deep fibular nerve). Medial tibial stress syndrome ("shin splints") affects the posteromedial tibial border instead.

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.