eversion

Eversion is the act of turning a body part outward, away from the midline. In anatomy, eversion refers to turning a part laterally and is the opposite of inversion, which turns a part inward. The term is used in various medical contexts, including ophthalmology (eyelid eversion) and surgical descriptions where tissues are turned inside out. The word derives from Latin eversionem, from e- “out” and vertere “to turn.”

In the foot, eversion occurs at the subtalar joint, causing the sole to tilt away from the midline. The primary evertors are the peroneus longus and peroneus brevis; invertors are the tibialis anterior and tibialis posterior. A normal amount of eversion helps with shock absorption during walking, but excessive eversion is associated with overpronation and can contribute to injuries such as plantar fasciitis, medial knee strain, and ankle instability.

Eyelid eversion is a clinical maneuver in which the upper or lower eyelid is rolled away from the eyeball to expose the palpebral conjunctiva. It is routinely performed during eye examinations to inspect for foreign bodies, conjunctival pathology, or irritation. Eversion can also describe any procedure that turns a tissue outward to facilitate inspection or access.