IOO ATLAS AND TEXT- BOOK OF HUMAN ANATOMY. 



-The right tibia seen from in front (f). 

 -The right tibia seen from behind (f). 

 The right tibia seen from the outer surface (f). 

 The right fibula seen from the inner surface (-f ). 

 The right fibula seen from the outer surface (f). 

 The tibia and fibula seen from behind (f). 

 The upper ends of the tibia and fibula seen from above (^-). 

 152. — The lower ends of the tibia and fibula seen from below (^). 



of the tibia, the infraglenoidal margin (Fig. 144), and at the lower portion of the external surface 

 of this margin is an almost flat, elliptical, articular surface for the head of the fibula (Fig. 145), 

 while below it, the anterior surface of the bone presents a large roughened elevation, the tuber- 

 osity (Fig. 144). The entire upper end of the tibia is bent slightly backward toward the shaft 

 of the bone (Fig. 146). 



The shajt of the tibia is of a distinctly triangular prismatic form. It is thick at its junction 

 with the upper extremity, and as it passes downward becomes more slender, at first gradually 

 and then rapidly (Figs. 144 to 146). It presents for examination three borders and three sur- 

 faces. The sharp anterior crest (Fig. 144), somewhat S -shaped and beginning at the lower 

 margin of the tuberosity, separates the internal and external surfaces, w T hile the equally sharp 

 interosseous ridge (Figs. 145 and 146), directed toward the fibula (Fig. 147), is situated between 

 the external and posterior surfaces. The third border of the tibia is rounded; it separates the 

 inner and posterior surfaces and is known as the internal border. 



The upper portion of the posterior surface of the shaft exhibits a rough line, the popliteal or 

 oblique line (Fig. 145), which passes from above downward and from without inward from the 

 articular surface for the fibula to the internal border. Below it is situated the nutrient foramen, 

 which is usually very large and distinct, and leads into a canal which passes obliquely downward. 

 The nutrient canal of the tibia consequently runs in an opposite direction to that of the femur. 



The inner surface of the tibia, like its anterior border, is situated immediately beneath the 

 skin and may be easily felt. The outer surface presents no special characteristics. Toward the 

 lower end of the bone the borders (with the exception of the interosseous ridge) become rounded 

 off, so that in this portion the bone is almost cylindrical. 



The inferior extremity of the tibia is considerably smaller than the upper one, but it is 

 distinctly thicker than the lower portion of the shaft. Its inferior surface (Fig. 152) presents a 

 slightly concave articular surface for the astragalus, and upon its inner side there is a process 

 which projects below the remainder of the bone and is known as the internal malleolus (Fig. 144). 

 The external surface of this process forms an articular surface for the astragalus, and is directly 

 continuous with the inferior articular surface of the bone. Upon the posterior surface of the 

 internal malleolus is a broad groove (Fig. 144) for the tendon of the tibialis posticus muscle, 

 and the outer surface of the lower end of the bone presents a notch, the fibular notch, for the recep- 

 tion of the fibula (Fig. 146), this notch not being, however, an articular surface and therefore 

 not being covered wvvith cartilage 



