The tibialis anterior is a muscle that originates towards the top and outside of the of the tibia— the larger and more medial (inner) of the two shin bones—and inserts into the medial cuneiform and first metatarsal bones of the foot The tibialis anterior also connects to the interosseous membrane a thin fibrous tissue that stabilizes the tibia to the fibula.
The tibialis anterior dorsiflexes the foot which means it flexes the foot in an upward direction such as drawing the toes towards the knee. It also inverts, or turns the foot in towards the midline of the body.
The tibialis is the only muscle at the front of the shin. And there isn’t much of it in comparison to the calf muscles at the back—soleus and gastrocnemius.
The tibialis anterior is a fusiform muscle which means it has a long thin shape that is wider in the middle and thinner at each end where it connects. A fusiform muscle is arranged this way to provide the greatest degree of flexion, which also allows for a wide range of motion.
This size and shape of the tibialis anterior is interesting in comparison to its counterpart the tibialis posterior. The tibialis posterior is a penniform muscle, a type of muscle shaped like a feather with a long line of attachment to the bone which makes this type of muscle very powerful (more on this at some point).
The tibialis anterior is an essential muscle for walking though it works differently if the foot is on or off the ground. It stabilizes the ankle when the foot is on the ground and pulls the foot off the ground to step forward, both of which it accomplishes through contraction (eccentric and concentric).
The tibialis anterior also works in a relationship with the tibialis posterior acting as both an antagonist and synergist. There is another fascinating relationship that the tibialis anterior has with the fibularis longus which I will explore in a future post.