THE TIBIA 



101 



small elevation near the distal end of the ])one. The internal border (Alargo medi- 

 alis) is rounded in its u})per half, to which th(> popliteus muscle is attached, and a 

 tubercle is found on this part. The lower part is a rough line on well-marked bones. 

 The external border (Crista interossea) is concave in its upper part and concurs 

 with the fibula in the formation of the interosseous space of the leg; a smooth im- 

 pression indicates the course of the anterior til)ial vessels through the space to the 



Spine 



External condyle 



Head of fibula 



Vascular impression \--~ 



Shaft of jibula — 

 External border of tibia 



T uberosity 



1^ " Groove for tendon of anterior 



extensor and peroneus tertius 



— Groove for lateral extensor tendon 



External malleolus 

 Fig. 68. — Right Tibia and Fibula of Horse, External View, 



front of the leg. Lower down the border di\-ides and incloses a narrow triangular 

 surface. 



The proximal extremity (Extremitas proximalis) is large and three-sided. It 

 bears two lateral eminences, the internal and external condyles (Condylus medialis, 

 laterahs). Each presents a somewhat saddle-shaped surface for articulation with 

 the condyle of the femur and the semilunar cartilage. The spine or intercondy- 

 loid eminence (Eminentia intercondyloidea) is the central prominence, upon which 

 the articular surfaces are continued; it consists of a high inner part and a lower 



