208 FIBULA. 



broader below, where it has the print of the peroneus tertius. 

 The posterior plane is broad and hollow, giving origin to the 

 larger share of the tibialis posticus. The internal angle of this 

 bone has a tendinous membrane fixed to it, from which some 

 fibres of the flexor digitorum longus take their rise. The 

 posterior surface of the fibula is the plainest and smoothest ; 

 but is made flat above by the splaeus, and is hollowed below by 

 the flexor pollicis longus. In the middle of this surface, 

 the canal for the medullary vessels may be seen slanting 

 downwards. 



The lower end of the fibula is extended into a spongy oblong 

 head : on the inside of which is a convex, irregular, and 

 frequently a scabrous surface, that is received by the external 

 hollow of the tibia, and so firmly joined to it by a very thin 

 intermediate cartilage and strong ligaments, that it scarce can 

 move. Below this the fibula is stretched out into a smooth 

 coronoid process, covered with cartilage on its internal side, 

 and is there contiguous to the outside of the first bone of the 

 foot, the astragalus, to secure the articulation. This process, 

 named malleolus externus, being situated farther back than is 

 the internal malleolus, and in an oblique direction, obliges us, 

 naturally, to turn the forepart of the foot outwards. At 

 the lower internal part of this process, a spongy cavity for 

 mucilaginous glands may be remarked ; from its point, ligaments 

 are extended to the bones of the foot, viz. the astragalus, os 

 calcis, and os naviculare ; and from its inside, short strong ones 

 go out to the astragalus. On the back part of it a sinuosity is 

 made by the tendons of the peronei muscles. When the 

 ligament, extended over these tendons from the one side of the 

 depression to the other, is broken, stretched too much, or made 

 weak by the sprain, the tendons frequently start forwards to the 

 outside of the fibula. 



The conjunction of the upper end of the fibula with the 

 tibia is by plain surfaces tipped with cartilage ; and at its lower 

 end the cartilage seems to glue the two bones together; not, 

 however, so firmly in young people, but that the motion at the 

 other end is very observable. In old subjects, the two bones 



