224 SKELETON. 



The superior face is deeply scooped out, at its fore part, and 

 is formed there into two articular surfaces, for joining with the 

 astragalus: these faces are separated from each other by a rough 

 fossa, which runs from within obliquely forwards and outwards. 

 The anterior external part of this fossa is deep, broad, and tri- 

 angular; the posterior part is narrow, is occupied by a ligament, 

 and allows the two articular surfaces to come nearer. Just 

 behind the fossa is the first articulating surface, lying parallel 

 with it; being oblong, convex, semi-cylindrical, and looking 

 obliquely upwards and forwards. Before the fossa is the se- 

 cond surface: it is oblong, much smaller than the first, and is 

 very frequently divided into two by a transverse notch, and is 

 concave. The part of the bone upon which this face is wrought, 

 is called, by the French, the little apophysis. I have frequent- 

 ly remarked, that the face posterior to the first mentioned fossa 

 is smaller and more vertical in the African than in the Eu- 

 ropean; the os calcis, behind it, is also smaller and longer. 

 The upper posterior face of the bone is somewhat concave. 



The under surface of the os calcis is slightly concave, longi- 

 tudinally. It is bounded, behind, by two tuberosities, of which 

 the internal is larger than the external; they both give origin 

 to muscles of the sole of the foot and to the aponeurosis 

 plantaris. There is also a tuberosity bounding the same sur- 

 face in front, from which arise the ligaments that connect this 

 bone with the adjoining ones. . 



The anterior extremity of the os calcis forms the greater 

 apophysis, and is terminated in front by a triangular and slight- 

 ly concave surface, by which it articulates with the os cu- 

 boides. The posterior extremity is convex and rough : con- 

 stitutes the heel, and near its middle receives the tendo-achillis; 

 the upper part is sloping and more smooth, in order to accom- 

 modate this tendon in the flexions of the foot. 



The external surface of the os calcis is flat, with the excep- 

 tion of a gentle rising in its middle; it is marked, occasionally, 

 by a superficial groove, indicating the course of the peronei 

 muscles. The internal surface is very concave, and obtains the 

 name of sinuosity; along it pass the tendons of several muscles 



