Tibialis anterior muscle
|Tibialis anterior muscle|
Lateral aspect of right leg.
|Latin||musculus tibialis anterior|
|Upper 1/2 & Lateral Condyle of Tibia|
|medial cuneiform and first metatarsal bones of the foot|
|anterior tibial artery|
|Deep Fibular (peroneal) nerve (L5)|
|Actions||Dorsiflexion and Inversion of the foot|
|Fibularis longus, Gastrocnemius, Soleus, Plantaris, Tibialis posterior|
|Anatomical terms of muscle|
In human anatomy, the tibialis anterior (// or //) is a muscle that originates in the upper two-thirds of the lateral (outside) surface of the tibia and 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.
It arises from the lateral condyle and upper half or two-thirds of the lateral surface of the body of the tibia; from the adjoining part of the interosseous membrane; from the deep surface of the fascia; and from the intermuscular septum between it and the extensor digitorum longus.
The fibers of this fusiform muscle are relatively parallel to the plane on insertion, ending in a tendon, apparent on the anteriomedial dorsal aspect of the foot close to the ankle.
After passing through the most medial compartments of the transverse and cruciate crural ligaments, it is inserted into the medial and under surface of the medial cuneiform bone and the base of the first metatarsal bone.
Deep peroneal (fibular) nerve, branch of common peroneal (fibular) nerve (L4, L5, S1).
The tibialis anterior muscle is the most medial muscle of the anterior compartment of the leg. The tibialis anterior is responsible for dorsiflexing and inverting the foot. The muscle has two origins, one being the lateral tibial condyle and the other being the upper lateral surface of the tibia, and inserts on the medial surface of the medial cuneiform and adjoining part of base of the first metatarsal of the foot allowing the toe to be pulled up and held in a locked position. It also allows for the ankle to be inverted giving the ankle horizontal movement allowing for some cushion if the ankle were to be rolled. It is innervated by the deep peroneal nerve and acts as both an antagonist and a synergist of the tibialis posterior. However, the most accurate antagonist of the tibialis anterior is the peroneus longus. The tibialis anterior aides in the activities of walking, running, hiking, kicking a ball, or 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.
Essentially, 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.
Traumatic injuries to the lower limb are often associated with contact team sports. Injuries in the foot and ankle have been reported to account for up to 25% of injuries in 19 sports. In a case report of a 22 year old female university student, the athlete sustained an injury from the impact of kicking the ball in a game of Gaelic football. Examinations of the athlete revealed foot drop gait, lack of active dorsiflexion, and a visibly apparent and palpable absence of the tibialis anterior tendon at the ankle. The foot drop gait and the lack of active dorsiflexion can be explained by the absence of the tibialis anterior tendon. The tibialis anterior tendon is responsible for dorsiflexion and inverting the foot. It also resists backward tipping of the body such as standing on a moving boat deck and helps support the medial longitudinal arch of the foot. The absence of the muscle would lead to the lack of dorsiflexion and a foot drop gait that makes walking a challenge. Surgery revealed a complete traumatic tear of the tibialis anterior at the musculotendinous junction which was subsequently sutured back to the belly where the rupture had occurred through absorbable interrupted sutures.
|Wikimedia Commons has media related to Tibialis anterior muscle.|
- Origin, insertion and nerve supply of the muscle at Loyola University Chicago Stritch School of Medicine
- Anatomy photo:15:st-0415 at the SUNY Downstate Medical Center
- Constantinou, M (2004). "Traumatic Tear of Tibialis Anterior during a Gaelic Football Game: A Case Report". British Journal of Sports Medicine 38 (6). doi:10.1136/bjsm.2003.007625.
- Saladin, Kenneth (2015). Anatomy & Physiology: The Unity of Form and Function (7 ed.). McGraw-Hill Education. ISBN 978-0-07-340371-7.