Corpus: Tibialis anterior muscle
Synonym: anterior tibial muscle
1. Definition
The tibialis anterior muscle is a long, spindle-shaped skeletal muscle located in the lower extremity. It belongs to the anterior group of lower leg muscles, functioning primarily as an extensor.
2. Anatomy
2.1. Origin
The origin of the tibialis anterior muscle is the lateral condyle and the proximal half or proximal two-thirds of the lateral surface of the tibia. Additional fibers originate from the interosseous membrane and the muscular septum, which separates it from the extensor digitorum longus muscle.
2.2. Attachment
The tendon of the tibialis anterior muscle passes under the superior and inferior extensor retinaculum of the foot on the medial side of the ankle joint to the foot. It attaches plantarly to the medial cuneiform bone and dorsally to the base of the first metatarsal bone. The subtendinous bursa of tibialis anterior is situated between the tendon and the bone near the attachment point.
2.3. Topography
In the proximal part of the lower leg, the muscle overlies the anterior tibial artery and the deep fibular nerve.
3. Innervation
The tibialis anterior muscle is innervated by the deep fibular nerve (segments L5, S1), which is a branch of the common fibular nerve from the sciatic nerve.
4. Function
The tibialis anterior muscle facilitates dorsiflexion or extension, supination, and adduction of the foot. Its traction helps stabilize the ankle joint, particularly during the initial phase of ground contact when walking or running. It acts as an antagonist to the fibularis longus muscle.
5. Clinic
Paralysis of the tibialis anterior muscle results in a condition known as stepper gait.