J 22 Bones of tte Leg. [Book IX. 



The leg has three bones, the tibia, the fibula, and 

 the patella. The tibia, which is the principal bone 

 of the kg, is a cylindrical bone of a ti iangular form, 

 larger above than below. The upper end of the 

 tibia is large, bulbous, and fpongy, and is divided 

 into two cavities by a rough irregular protuberance, 

 which is hollow at its mod prominent part, as well 

 before as behind. The two broad cavities at the 

 fide of this protuberance are not equal ; for the in- 

 ternal is oblong and deep, for receiving the internal 

 condyl of the os femoris ; while the external is more 

 fuperficial and rounder, for the external condyl. 

 The circumference of thefe* cavities is rough and 

 unequal, for the firm connection of the ligaments 

 of the joint. In this manner is formed a hinge or 

 ioint, which admits of motion in only two directions. 

 At the back part of this bone the fame canal is con- 

 tinued between the condyls, for tranfmitting blood- 

 veffels and nerves, as in the os femoris ; and there 

 are two eminences for the infertion of the other ends 

 of the crucial ligaments. At the interior part of this 

 bone is a cavity for the reception of the patella, which 

 correfponds with one between the condyls of the os 

 femoris. Below the external edge of the upper end 

 of the tibia is a flat furface of cartilage, for the con- 

 nection of the fibula ; and at its lower end therq 

 is a longitudinal cavity on the outfide, for receiving 

 the lower part of the fame bone. On the internal 

 part of the bottom of the tibia is a procefs, which 

 forms the inner malleolus or ankle-bone. Still lower, 

 at the extremity of the tibia, is a tranfverfe articulat- 

 ing cavity, covered with cartilage, and divided by a 

 ridge, which receives a bone of the foot called the 

 aftragalus.. The body of the tibia has three angles, 

 and as many flat furfaces. One of the flat furfaces 



