astragali

Astragalus is a term used for a bone in the ankle, with the plural form astragali in Latin. In anatomical usage, the astragalus refers to the talus, the bone that forms the lower part of the ankle joint. Each human foot contains one talus, so an adult has two astragali, one on each side.

Anatomy and function: The talus sits between the lower leg bones (the tibia and fibula) and the foot. Its upper surface forms the ankle mortise with the tibia and fibula, allowing dorsiflexion and plantarflexion of the foot. The inferior surface articulates with the calcaneus (heel bone) at the subtalar joint, enabling inversion and eversion. The head of the talus articulates with the navicular bone anteriorly. The talus has no muscular attachments and is stabilized by ligaments and surrounding soft tissues. Its unique shape and central position in the foot make it critical for transferring body weight from the leg to the foot and for maintaining ankle stability.

Clinical notes: The talus can be injured through falls or high-energy trauma, with fractures of the talar neck being particularly serious due to the risk of disrupted blood supply and avascular necrosis. Degenerative changes can occur with age, injury, or uneven load bearing, sometimes contributing to ankle or subtalar joint arthritis.

Other uses: In archaeology and cultural history, astragali (knucklebones) are the ankle bones from sheep or goats used as gaming pieces in ancient cultures, serving as dice or for divination. The term and its plural are also used in zoology to describe the same bone in various vertebrates.