What is the main function of the tibialis posterior muscle?

The tibialis posterior muscle plays a crucial role in the movement and stability of the foot and ankle. Its primary functions include plantarflexion and inversion of the foot.

Plantarflexion is the movement that points the toes downward, which is essential for activities such as walking, running, and jumping. This action comes into play particularly during the push-off phase of gait when one needs to propel the body forward.

Inversion refers to the movement that turns the sole of the foot inward. This function is vital for maintaining balance and adapting to uneven surfaces. It helps keep the foot stable during activities that require lateral stability and control.

These dual functions of the tibialis posterior are integral for both mobility and endurance, particularly in maintaining the arch of the foot and accommodating the body's weight during movement.