THE TIBIA. 



295 



Styloid process. 



Fibula. 





outward by the tendons of the fol- 

 lowing muscles : Tibialis anticus, 

 Extensor proprius hallucis. Ex- 

 tensor longus digitoruui. 



The posterior surface (Fig. 221) 

 presents, at its upper part, a prom- 

 inent ridge, the oblique lint' of the 

 tibia, which extends from the back 

 part of the articular facet for the 

 fibula obliquely downward, to the 

 internal border, at the junction of 

 its upper and middle thirds. It 

 marks the limit for the insertion 

 of the Popliteus muscle, and serves 

 for the attachment of the popliteal 

 fascia and part of the Soleus, 

 Flexor longus digitorum, and Tib- 

 ialis posticus muscles : the tri- 

 angular concave surface, above and 

 to the inner side of this line, gives 

 attachment to the Popliteus mus- 

 cle. The middle third of the pos- 

 terior surface is divided by a 

 vertical ridge into two lateral 

 halves : the ridge is well marked 

 at its commencement at the oblique 

 line, but becomes gradually indis- 

 tinct below : the inner and broader 

 half gives attachment to the Flexor 

 longus digitorum, the outer and 

 narrower to part of the Tibialis 

 posticus. The remaining part of 

 the bone presents a smooth surface 

 covered by the Tibialis posticus, 

 Flexor longus digitorum, and 

 Flexor longus hallucis muscles. 

 Immediately below the oblique line 

 is the medullary foramen, which is 

 directed obliquely downward. 



The Lower Extremity, much 

 smaller than the upper, presents five 

 surfaces : it is prolonged downward, 

 on its inner side to a strong pro- 

 the internal. iiinlh'<;lns. The 

 i)it\ //->/ surface of the bone is 

 quadrilateral, and smooth for artic- 

 ulation with the astragalus. This 

 surface is concave from before back- 

 ward, and broader in front than be- 

 hind. It is traversed from before 

 backward by a slight elevation, 

 separating two lateral depressions. 

 It is narrow internally, where the 

 articular surface becomes continu- 

 ous with that on the inner malleolus. The anterior surface of the lower extrem- 

 ity is smooth and rounded above, and covered by the tendons of the Extensor 

 muscles of the toes ; its lower margin presents a rough transverse depression, for 



FIG. 221. Bones of the right leg. Posterior surface. 



