THE LEG. 217 



SECT. II. OF THE LEG. 



Two bones form the leg, the tibia and the fibula, to which 

 may be added the patella, from its attachment to the tibia. 



Of the Tibia, (Tibia.) 



The tibia is placed at the internal side of the leg, and extends 

 from the thigh to the foot. After the os femoris, it is the long- 

 est and the largest bone in the skeleton. It is divided into the 

 body and the two extremities. 



The superior extremity of the tibia is oval, transversely, and 

 presents an extent of surface suited to the articular face of the 

 two condyles of the os femoris, to which it is joined. It has 

 here two superficial cavities for receiving the ends of the con- 

 dyles; one of them is internal and the other external. The in- 

 ternal is the deeper and more extensive of the two, and, being 

 oval, has its long diameter in an antero-posterior direction. 

 The external, besides being smaller and more superficial, is 

 more circular; and, from the want of elevation in its margins, 

 scarcely presents at all the appearance of a cavity. These 

 two cavities, which approach to within half an inch of each 

 other, are kept entirely separated by an elevated triangular 

 ridge, with a broad base, called the spinous process of the tibia. 

 The summit of the ridge presents two tubercles, one at each 

 end, separated by a pit, which serves to attach the posterior 

 end of the external semi-lunar cartilage. The ridge is placed 

 nearer the posterior than the anterior margin of the tibia. Its 

 base, in front, is depressed by the attachment of the anterior 

 crucial ligament, and just before this is a rough, triangular 

 space, extending to the anterior margin of the bone, and co- 

 vered by fat in the recent subject. Between the ridge and 

 the posterior margin of the bone is a deep depression for the 

 attachment of the posterior crucial ligament. 



The circumference of the superior part of the tibia, just be- 

 low its articular surface, is flat before, somewhat flat and con- 

 VOL. I. 19 



