Astragalos

Astragalos, usually rendered astragalus in English, refers to several related uses tied to the notion of a knucklebone or ankle bone. In anatomy, it denotes the astragalus or talus, the uppermost ankle bone that connects the leg to the foot. In archaeology and gaming, astragali are knucklebones used as dice. In botany, the name appears in the genus Astragalus, the milkvetches.

Anatomically, the astragalus is a short, wedge-shaped bone that forms the core of the ankle joint. It articulates superiorly with the tibia and fibula and inferiorly with the calcaneus, with additional facets for adjacent bones such as the navicular. It helps transmit body weight from the leg to the foot and enables hinge-like motion of the ankle, including dorsiflexion and plantarflexion.

Historically, astragali—knucklebones—were used as gaming pieces. Made from the tarsal bones of sheep or goats, players tossed them to generate numbers and determine outcomes in various games. The practice also had divinatory associations in some cultures and regions of the ancient world.

Botany, the term appears in the large genus Astragalus within the legume family Fabaceae. This genus encompasses thousands of species, known commonly as milkvetches. They occupy a wide range of habitats and ecological roles; some species are important forage crops, while others have medicinal or toxic properties. Astragalus membranaceus is a well-known species used in traditional Chinese medicine as huang qi.

Etymology stems from Greek astragalos meaning “ankle bone” or “knucklebone,” a reflection of the bone’s historical and linguistic significance.