tibialis

Tibialis is a term used in anatomy to denote muscles in the lower leg that are associated with the tibia or are located near it. In humans, the principal muscles bearing this name are the tibialis anterior and the tibialis posterior. They belong to different compartments of the leg and contribute to distinct movements of the foot and ankle.

Tibialis anterior is found in the anterior compartment of the leg. It originates from the lateral condyle and upper two-thirds of the lateral surface of the tibia, and from the interosseous membrane. It inserts on the medial and plantar aspects of the first metatarsal base and the medial cuneiform. Its primary actions are dorsiflexion of the ankle and inversion of the foot. It is innervated by the deep peroneal (fibular) nerve and supplied by the anterior tibial artery. Clinically, it can be involved in overuse injuries such as shin splints or tibialis anterior tendonitis.

Tibialis posterior lies in the deep posterior compartment. It originates from the posterior surfaces of the tibia and fibula and the interosseous membrane. It inserts mainly on the navicular and other tarsal bones, with extensions to the cuneiforms and bases of the metatarsals. Its actions include plantarflexion of the ankle and inversion of the foot, and it helps support the medial arch. It is innervated by the tibial nerve and supplied by the posterior tibial artery. Dysfunction of this muscle or tendon can contribute to flat foot and related instability.