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Other Terms: Heel bone, Os calcis, Calcanéus
Inspection of the calcaneus reveals an irregular shaped rectangular cube with its long axis similar to the long axis of the foot. Its distal face forms a small, smooth articular surface. Its posterior or proximal face forms a roughened calcaneal tubercle. The dorsal face forms wide, smooth articular surfaces anteriorly becoming rough and narrowed posteriorly. Both plantar and lateral faces are rough and flattened. The medial face presents as a shallow hollow.
This is a Latin term that came to mean the heel. Its origin is from the Latin calx that translates as chalk or limestone, possibly from its appearance to a chunk of limestone.
The calcaneus articulates with two bones: the talus and cuboid. There are three articular surfaces for the talus. The largest is the slightly convex oval surface for the body of the talus. Anteromedial to this is the medial articular surface for the talus on the dorsal aspect of the sustentaculum tali. Anterolateral to this surface is the small anterior facet for the talus, which may sometimes blend with the medial facet. The latter two facets are shallowly concave. The distal end forms an obliquely directed, oval, articular surface that is convex in the transverse plane and concave in the vertical plane. This surface articulates with the cuboid bone.
Ossification of the calcaneus typically occurs from one central center forming during the sixth fetal month, but variations to this onset can range from anywhere between the fourth and seventh month. A second epiphyseal center appears as a distal lateral cap beginning in the sixth year in females and the eighth year in males. This epiphysis fuses to the main bone during the fourteenth and sixteenth year respectively.