Tibialis Anterior Muscle

The tibialis anterior (TA), the most medial and superficial dorsiflexor, is a slender muscle that lies against the lateral surface of the tibia. The long tendon of TA begins halfway down the leg and descends along the anterior surface of the tibia. Its tendon passes within its own synovial sheath deep to the superior and inferior extensor retinacula to its attachment on the medial side of the foot. In so doing, its tendon is located farthest from the axis of the ankle joint, giving it the most mechanical advantage and making it the strongest dorsiflexor.

Although antagonists at the ankle joint, tibialis anterior and the tibialis posterior (in the posterior compartment) both cross the subtalar and transverse tarsal joints to attach to the medial border of the foot. Thus, they act synergistically to invert the foot.

See Also: Tibialis Posterior Muscle

Tibialis Anterior Anatomy

The tibialis anterior lies superficially and is easily palpable just lateral to the anterior border of the tibia. As the foot is inverted and dorsiflexed, the large tendon of the tibialis anterior can be seen and palpated as it runs distally and slightly medially over the anterior surface of the ankle joint to the medial side of the foot.

Origin

The tibialis anterior muscle originates from the lateral condyle of tibia, proximal 1/2 – 2/3 or lateral surface of tibial shaft, interosseous membrane and from deep surface of the fascia cruris.

Insertion

Its tendon passes under superior and inferior extensor retinacula and insert on medial and plantar surfaces of 1st cuneiform and on base of first metatarsal.

Innervation

Tibialis anterior muscle is innervated by the deep peroneal nerve (L4, L5).

Blood Supply

It’s supplied by the anterior tibial artery.

Action

The tibialis anterior muscle acts to dorsiflex the ankle joint and inverts the hindfoot. During gait cycle, it dorsiflexes the foot in preparation for heel strike (late swing phase). TA Eccentrically contracts after heel strike.

Tibialis Anterior Strain

Tibialis anterior strain (Shin Splints) is characterized by edema and pain in the area of the distal two thirds of the tibia, results from repetitive microtrauma of the tibialis anterior, which causes small tears in the periosteum covering the shaft of the tibia and/or of fleshy attachments to the overlying deep fascia of the leg.

Shin splints are a mild form of the anterior compartment syndrome. Shin splints commonly occur during traumatic injury or athletic overexertion of muscles in the anterior compartment, especially tibialis anterior, by untrained persons. Often, persons who lead sedentary lives develop shin splints when they participate in long-distance walks. Shin splints also occur in trained runners who do not warm up and cool down sufficiently. Muscles in the anterior compartment swell from sudden overuse, and the edema and muscle tendon inflammation reduce the blood flow to the muscles. The swollen muscles are painful and tender to pressure.

Rupture of the tibialis anterior tendon (TAT) is an uncommon pathology. However, in the event of a rupture, if the patient experiences significant loss of dorsiflexion and inversion accompanied by gait disorder, the treatment of choice is surgical repair or reconstruction. In surgery, the tendon is reattached to the bone.

To test the tibialis anterior, the person is asked to stand on their heels or dorsiflex the foot against resistance; if normal, its tendon can be seen and palpated.

References & More

1. Clinically Oriented Anatomy – 8th Edition
2. Juneja P, Hubbard JB. Anatomy, Bony Pelvis and Lower Limb: Tibialis Anterior Muscles. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513304/