164 



Anatomy of Skeleton 



vertical lines (Fig. 134) and extends up to the outer part of the oblique line. Flexor 

 longus digitorum arises from the bone internal to the vertical line and below the oblique 

 line, which gives origin to the tibial head of Soleus : Soleus origin extends down the 

 inner margin also for a variable distance. 



We can now analyse the oblique line and see that (Fig. I33A) its value differs in its 

 inner and outer parts : an attempt should be made to recognise the various points 

 on the bones. The Tibialis posticus passes obliquely across the back of the bone from 

 its origin to the groove on the back of the malleolus, and is crossed by the Flexor 

 longus digitorum. Therefore, on the outer side of the groove, between it and the 

 groove for the long flexor of the great toe, the back of the lower end of the bone is in 

 relation with the long flexor of the other toes and the posterior tibial vessels and nerve. 



The deep transverse fascia of the leg separates the deep flexors and main vessels 

 lying on them from the Soleus. It is attached to the inner margin of the bone, then 

 between the Soleus and F. longus dig. to reach the tubercle from which its attach- 

 ment passes along the fibrous arch over the main vessels to reach the head of the 



F. loao. 



m. 



FIG. 136. Posterior view of right ankle, and of right tibia. 



fibula. It is thickened below, where it is fastened to the malleolus, to form the internal 

 annular ligament ; just below the origin of Soleus it is joined at the inner margin by 

 the deep fascia covering over that muscle, but lower down the deep fascia runs into it 

 further from tlje margin as the Soleus narrows to its insertion, so that the annular 

 ligament is really a compound of the two fasciae behind the inner ankle. 



The lower epiphysis includes the fibular facet : it has nothing attached to it but 

 ligaments. 



Observe that the posterior margin of the lower articular surface comes down lower 

 than the anterior margin, but the anterior margin is wider. 



The articular surface is concave sagittally and slightly convex from side to side, 

 corresponding with the surface of astragalus : among the ligamentous markings 

 round its margins may be found one for the transverse posterior ligament (Fig. 136). 

 The surface is prolonged on to the malleolus. 



Observe that the malleolus has its long axis directed downwards and forwards : 

 the attachments of ligaments to it are shown in the figures. 



The inner surface and subcutaneous border of the bone can be directly palpated 

 during life, practically throughout its extent. The whole upper end can be taken 

 between thumb and fingers and examined, but its central front part, above the tubercle, 

 is hidden by the patellar tendon and infrapatellar pad. 



