220 SKELETON. 



is cellular at its extremities ; but compact in the body, where it 

 presents a cavity occupied by cancellated matter. It will now 

 be understood how it articulates with the fibula, externally, at 

 both ends; with the os femoris above; and with the astragalus 

 below. 



Of the Fibula, (Ptront.) 



The fibula is placed at the external side of the tibia, and ex- 

 tends from the head of the latter to the foot : it is much smaller, 

 and not quite so long as the tibia, and is so articulated with it 

 as to be on a line with its posterior face. It is to be studied in 

 its two extremities and in its body. 



The upper extremity of the fibula is considerably enlarged 

 and irregular. It presents, above, a small articular face di- 

 rected upwards and very slightly concave, by which it joins the 

 corresponding face of the tibia. This surface is bounded be- 

 hind by a sort of styloid process, into which is inserted the ten- 

 don of the biceps flexor cruris. The circumference of the bone, 

 in advance of this, furnishes attachment to the external lateral 

 ligament of the knee. 



The inferior extremity of the fibula is also enlarged, being 

 flattened on its tibial side, but more rounded externally. This 

 part of the fibula is called the malleolus externus. It descends 

 lower than the internal ankle,, and is also more prominent and 

 large. Its tibial side presents, below, a small triangular slightly 

 convex articulating surface, which reposes against the side of 

 the astragalus ; behind, and somewhat below it, is a small rough 

 depression, which, with the adjoining inferior margin of the bone, 

 gives origin to the three fasciculi of the external lateral ligament 

 of the ankle. Above the articular surface, the bone is rough 

 and slightly rounded where it is received into the side of the 

 tibia, and sends oft' many short ligamentous fibres to it. The 

 anterior margin of this extremity of the fibula is thin and pro- 

 jecting, the posterior surface is flat and broad, and is slightly 

 scooped out into a longitudinal groove, which transmits the 

 tendons of two peronei muscles. The pointed termination 

 below, of the malleolus externus, is sometimes called the coro- 

 noid process. 



