Which muscle everts the subtalar ankle joint?

The muscle responsible for everting the subtalar joint is the peroneus longus. Eversion refers to the motion that turns the sole of the foot outward, away from the midline of the body. The peroneus longus, along with the peroneus brevis, plays a key role in this movement by allowing the lateral aspect of the foot to lift and rotate outward during activities such as walking and running.

The action of the peroneus longus is particularly important in maintaining balance and stability on uneven surfaces, as well as assisting in the overall mobility of the foot and ankle. The muscle originates from the upper part of the fibula and runs down the lateral side of the leg, eventually attaching to the base of the first metatarsal and the medial cuneiform bone, which facilitates its evertor function.

The other options pertain to different muscle actions: tibialis anterior primarily acts as a dorsiflexor and inverter of the foot, the brachialis is involved in elbow flexion (having no role in ankle or foot movements), and the adductors are responsible for bringing the thighs together and do not influence the subtalar joint at all.