THE SKELETON. 



cuneiform, mesocuneiform, and entocuneiform. The os 

 calcis, or calcaneum, is the largest 

 bone of the tarsus, being twice as 

 long as broad (Fig. 43). Its caudal 

 end presents a groove for the ten- 

 don of the plantaris muscle. The 

 peroneal tubercle is on the outer 

 side of the distal extremity. The 

 sustentaculum, a shelf-like pro- 

 cess projecting from near the 

 middle of the inner side, supports 

 a facet for the tendon of the 

 flexor longus digitorum muscle 



(Fig. 53)- 

 The astragalus lies on the inner 



or mesal side of the calcaneum and 

 articulates with the tibia, fibula, cal- 

 caneum, and navicular. The bone 

 is composed of a body, neck, and 

 head. The body is proximal and 

 bears a trochlear surface for articu- 

 lation with the tibia. The head 

 bears a convex surface for articu- 

 lation with the navicular. The neck 

 is the constricted portion between 

 the body and the head. 



The navicular lies on the mesal 

 side of the foot and articulates with 

 the remaining six bones of the tar- 

 sus. It may be recognized by its 

 deep concave surface for articula- 

 tion with the astragalus, and also 



by the tuberosity, a process on its mesal plantar angle 

 (Fig. 43)- 



FIG. 43. DORSAL ASPECT 

 OF LEFT HIND-FOOT. 



ag, Astragalus; ar, articu- 

 lar surface of the tibia ; 

 cb, cuboid; cc, ectocu- 

 neiform; gr, groove for 

 the tendon of the plan- 

 taris; h, head of the 

 fourth metatarsal ; ic, 

 entocuneiform ; me, 

 mesocuneiform ; m } , hal- 

 lux or first metatarsal ; 

 w 2) w 3 , m 4 , and rw 5 , sec- 

 ond, third, fourth, and 

 fifth metatarsals ; nv, 

 navicular or scaphoid; 

 oc, os calcis, or calca- 

 neum; 3, proximal row 

 of phalanges; 2, middle 

 row of phalanges ; 1 , dis- 

 tal row of phalanges. 



