User:Tanyanika/Tibialis Anterior Draft

The tibialis anterior muscle is the most medial muscle of the anterior compartment of the leg. It functions to stabilise the ankle as the foot hits the ground during the contact phase of walking and acts later to pull the foot clear of the ground during the swing phase.

It originates from the lateral condyle of tibia, proximal ½ to 2/3’s of the lateral surface of the tibial shaft, the interosseous membrane between the tibia and fibula and the adjacent parts of the deep fascia enclosing the entire anterior compartment. From here it extends downwards and across to the medial aspect of the foot, anterior to the medial malleolus, but passing underneath the inferior and superior retinaculae, which prevent bowstringing of the tendon. The tendon is protected from friction from these two structures by a surrounding bursa. Tendon insertion is primarily on the plantar and medial surface of the medial cuneiform bone and also the plantar surface of the base of the first metatarsal. Its synergists are extensor digitorum longus and extensor hallucis longus.

Antagonists – plantar-flexors of the posterior compartment such as soleus and gastrocnemius

Essentially, the movements of tibialis anterior are dorsiflexion and inversion of the foot. 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. When the foot is off the ground, This muscle must produce at least 10deg of dorsiflexion to allow the foot

Pathology involving tibialis anterior

Related Topics

• Anterior Compartment
• Gait
• Leg anatomy

References

Romanes, G.J. (1996) Cunningham's Manual of Practical Antatomy; Vol. 1: Upper and Lower Limbs Fifthteenth Edition Oxford University Press New York

External Links

• Wheeless' Textbook of Orthopaedics http://www.wheelessonline.com/ortho/tibialis_anterior
• Lower Extremity Muscle Atlas http://www.rad.washington.edu/atlas2/tibialisanterior.html
• Gray's Anatomy - The Muscles and Fasciæ of the Leg http://education.yahoo.com/reference/gray/subjects/subject?id=129#i437