Understanding the Subtalar Joint
The subtalar joint, sometimes referred to as the talocalcaneal joint, is a crucial part of the ankle complex. Located at the meeting point of the talus and the calcaneus, this joint plays a significant role in the overall function and stability of the lower ankle. While some medical sources include the navicular bone as part of this joint, the true anatomical subtalar joint consists solely of the talus and the calcaneus.
Functionally, the subtalar joint is classified as a plane synovial joint, similar to a hinge joint but operating on a different axis. As a result, its range of motion is somewhat limited, allowing for only a few specific movements.
Understanding Ankle Inversion and Eversion
Aside from its primary function of extending and flexing, the ankle possesses the remarkable ability to move laterally as well, a movement known as pronation and supination. Two important movements that fall under this category are inversion and eversion. Eversion involves moving the foot outwards, shifting the weight onto the side of the foot that houses the big toe. Conversely, inversion refers to the movement of the foot inwards, shifting the weight onto the outer edge of the foot or the side where the little toe is located.