THE TARSUS 



The Tarsus (Ossa Tarsi). 



263 



The tarsal bones are seven in number, viz., the calcaneus, talus, cuboid, navicular, 

 and the first, second, and third cuneiforms. 



The Calcaneus (os calcis) (Figs. 264 to 267). The calcaneus is the largest of the 

 tarsal bones. It is situated at the lower and back part of the foot, serving to 

 transmit the weight of the body to the ground, and forming a strong lever for 

 the muscles of the calf. It is irregularly cuboidal in form, having its long axis 

 directed forward and lateralward; it presents for examination six surfaces. 



Sulcus calcanei 

 Middle articular surface for talus 



Posterior articular surface for talus 



Trochlear process 

 Groove for Peronceus longus 



Lateral process* 



Tuberosity 



FIG. 266. Left calcaneus, lateral surface. 



Middle articular surface for talus 



Sustentaculum tali 

 Posterior articular surface for talus 



Tuberosityi 



Anterior articular surface 

 for talus 



Sulcus for Flexor 



hallucis longus 

 Medial process 



FIG. 267. Left calcaneus, medial surface. 



For cuboid bone 



Surfaces. The superior surface extends behind on to that part of the bone which 

 projects backward to form the heel. This varies in length in different individuals, 

 is convex from side to side, concave from before backward, and supports a mass of 

 fat placed in front of the tendo calcaneus. In front of this area is a large usually 

 somewhat oval-shaped facet, the posterior articular surface, which looks upward 

 and forward ; it is convex from behind forward, and articulates with the posterior 

 calcaneal facet on the under surface of the talus. It is bounded anteriorly by a 

 deep depression which is continued backward and medialward in the form of a 

 groove, the calcaneal sulcus. In the articulated foot this sulcus lies below a similar 

 one on the under surface of the talus, and the two form a canal (sinus tarsi) for the 





