156 Anatomy of Skeleton 



really consisting of two tubercles placed side by side : the non-articular surface in 

 front of the spine is wide and triangular, but is narrowed behind and falls away in a 

 popliteal notch. 



The two masses of bone which support the inner and outer articular surface are 

 termed the inner and outer tuberosities respectively : the inner tuberosity has a groove 

 on its inner and back aspect for the insertion of Semimembranosus, and the outer 

 has the upper fibular facet, for the head of that bone, on its lower, outer, and back 

 aspect. 



On the front of the bone, between the two tuberosities and at a lower level, is the 

 prominent tubercle for the attachment of the ligamentum patellae : this process is 

 included in the epiphysis of the upper end. 



The shaft is broadened above and below, but is mainly three-sided : it has a 

 prominent anterior border (subcutaneous border), an inner or poster o-internal border, 

 and an outer or interosseous border : the subcutaneous inner surface is between the 

 front and inner margins, the slightly hollowed outer surface for the Tibialis anticus 

 lies between the anterior crest and the interosseous border, and the posterior surface 

 between the interosseous and inner margins. The posterior surface is wide above, 

 where the triangular area for insertion of Popliteus is bounded below by the oblique 

 line running down and in : below this the shaft is partly divided by the faint vertical 

 line into an outer area for Tibialis posticus and an inner for Flexor longus digit orum : 

 a large nutrient foramen, the largest in the body, is situated a little distance below 

 the oblique line. 



Towards its lower end the shaft enlarges and the anterior sharp margin becomes 

 less denned and turns somewhat inwards, so that the outer surface comes to look 

 a little forwards. 



The lower end, as a result of this thickening, presents an anterior surface Covered 

 by the tendons, etc., going to the dorsum of the foot, internal to which the ill-defined 

 front margin is prolonged down on to the front of the (internal) malleolus, a projection 

 downwards that forms the inner prominence of the ankle and rests against the side of 

 the astragalus : it consequently has an articular surface on its outer side. The inner 

 margin runs on to the inner and back part of the malleolus, and bounds a well-marked 

 groove for Tibialis posticus tendon. The posterior surface of the lower end presents, 

 in addition to this groove, a second broader but very badly marked groove further out 

 for tendon of F. longus hallucis. The outer surface presents a small lower fibular 

 facet or impression with a rough ligamentous area above it. The lower surface is articular 

 for the astragalus, concave from before backwards, and slightly convex from side 

 to side. 



FIBULA. (Fig. 129). 



The upper end, or head, is enlarged, presenting an articular surface for the tibia, 

 looking upwards, forwards, and inwards : behind and outside this a prominent styloid 

 process, for attachment of external lateral ligament and Biceps : the whole mass 

 is continuous below with the shaft at what is termed the neck. 



Shaft is long and slender, with a sharp anterior margin running up its length : 

 immediately internal to this is the narrow anterior surface, for the extensor muscles, 

 bounded by the interosseous or inner border : the flexor surface lies behind this and 

 comprises the inner and the posterior surfaces, which are separated to a great extent 

 by the poster o-internal . border that runs into the interosseous line in the lower part 

 of the shaft. The posterior surface lies between the postero-internal and the postero- 

 external border, and is for F. longus hallucis and, in its upper third, for Soleus, while 



