THE TIBIA. 



193 



Head 

 Styloid process. 



Tibia. 



flattened : it is triangular, broad 

 above, and perforated by large vas- 

 cular foramina ; narrow below, 

 where it terminates in a prominent 

 oblong elevation of large size, the 

 tubercle of the tibia ; the lower 

 half of this tubercle is rough, for 

 the attachment of the ligamentum 

 patellae ; the upper half presents a 

 smooth facet supporting, in the 

 recent state, a bursa which sep- 

 arates the ligament from the bone. 

 Posteriorly the tuberosities are 

 separated from each other by a 

 shallow depression, the popliteal 

 notch, which gives attachment to 

 part of the posterior crucial liga- 

 ment and part of the posterior 

 ligament of the knee-joint. The 

 inner tuberositi/ presents poste- 

 riorly a deep transverse groove, 

 for the insertion of one of the 

 fasciculi of the tendon of the 

 Semi-membranosus. Its lateral 

 surface is convex, rough, and 

 prominent : it gives attachment to 

 the internal lateral ligament. The 

 outer tuberositi/ presents posteriorly 

 a flat articular facet, nearly circu- 

 lar in form, directed dowmvard, 

 backAvard, and outward, for articu- 

 lation with the fibula Its lateral 

 surface is convex and rough, more 

 prominent in front than the in- 

 ternal : it presents a prominent 

 rough eminence, situated on a level 

 with the upper border of the tuber- 

 cle of the tibia at the junction of 

 its anterior and outer surfaces, for 

 the attachment of the ilio-tibial 

 band. Just below this the Ex- 

 tensor longus digitorum and a slip 

 from the Biceps are attached. 



The Shaft of the tibia is of a 

 triangular prismoid form, broad 

 above, gradually decreasing in size 

 to its most slender part, at the 

 commencement of its lower fourth, 

 where fracture most frequently 

 occurs ; it then enlarges again 

 toward its lower extremity. It 

 presents for examination three 

 borders and three surfaces. 



The anterior border, the most 

 prominent of the three, is called 

 the crest of the tibia, or, in popu- 

 lar language, the shin ; it commences above at the tubercle, and terminates below 



13 



Internal malleolus. 



External malleohts. 

 FIG. 133. Bones of the right leg. 



Anterior surface. 



