PELVIC LIMBS 



707 



extension of the "aponeurosis of the biceps femoris muscle. The tibia 

 has an upper extremity or head, a shaft, and a lower extremity. 



The Head is expanded from before backward and from side to side, 

 and each lateral mass is termed a tuberosity. 



The superior or proximal surface (Fig. 543) of the head is tri- 

 angular ; the apex of the triangle is directed to the front and slightly 



FIG. 543. 



Posterior Side. 



Posterior Crucial Ligament. 



Inner Tuberosity. 

 Inner Articular Surface 



Anterior Crucial Ligament. 



Tubercle with 



UGAMENTUM PATELL/E. 



External Semilunar Cartilage. 



Outer Articular Surface. 



Outer Tuberosity. 



Internal Semilunar 

 Cartilage. 



Groove for Tendon. 



Anterior Side. 



LEFT TIBIA, PROXIMAL END. 



outward ; the base, which nearly equals in length the two sides, faces 

 backward and somewhat inward. The triangular surface is divided by 

 a transverse depression into an anterior and a posterior half. 



The greater part of the anterior half is rough for ligamentous 

 attachment, and is pierced by numerous foramina for vessels. Its 

 well-defined lateral margins are distinctly emarginate, and the ante- 

 rior angle is transversely truncate. It is flat behind, and then gently 

 convex from behind forward ; it finally becomes more smooth, and 

 arches boldly downward to a transverse swelling of the upper end of 

 the anterior border of the bone, known as the tubercle of the tibia. 



The posterior half of the upper surface of the head is occupied by 

 the smooth outer and inner articular surfaces of the tuberosities and 

 the median antero-posterior groove which separates them. Its lateral 

 margins are gently arcuate ; the posterior margin is deeply incised in 

 the middle line by the popliteal notch. 



The outer articular surface is larger than the inner surface. It 

 is ovoid in outline, with the long axis directed from in front back- 

 ward and outward. From side to side it is gently concave, and from 

 before backward it is strongly arcuate. It is inclined from in front 



