54 ANATOMY AND PHYSIOLOGY. 



the fever and constitutional disturbance that arise when this joint 

 becomes inflamed. It lies very superficial, being covered only by 

 the skin in the greatest part of its extent, and hence it is very 

 easily wounded by a cut or prick from any sharp instrument. It is 

 never dislocated, except by such a force as destroys it altogether. 



The ankle is a hinge-joint, having one lateral ligament on its 

 inner, and three on its outer side. The upper surface of the astra- 

 galus^ as has been already said, is like the half of a broad pulley ; 

 it plays against the lower hollow end of the tibia, and is received 

 between the two ankles, formed by it and the fibula. This part of 

 the astragalus is narrower behind than in front, so that when the foot 

 is at right angles to the leg, as when we stand on it, the broad part 

 is between the ankles, and it is firmly fixed ; but when the foot is 

 extended, pointed downwards, the narrow part is brought between 

 them, so as to admit of the toes being directed to either side. The 

 ankle joint may be dislocated forwards or to either side. This 

 never happens without one <*f the ankles being broken off; the 

 ligaments being so strong that the bone will break rather than they 

 should give way. The dislocation of the ankle can scarcely take 

 place without a wound co-existing. I may here mention what is 

 meant by a compound, and w r hat by a simple dislocation. A simple 

 dislocation is one where the bones are displaced, but the skin is 

 unbroken ; a compound one is not more serious, in so far as the 

 bones are concerned, but is accompanied with a wound leading into 

 the joint. In the same way, a simple fracture is where a bone is 

 broken, without a wound ; a compound one is where there is a 

 wound communicating with the broken surfaces. The joints across 

 the foot are numerous. There is one joint across the middle of the 

 tarsus or solid part of the foot, which in some persons admits of 

 much lateral motion, and in such feet, is liable to be sprained. 

 Another joint runs across between the bones of the tarsus and those 

 of the instep. The joints of the toes require nothing particular to 

 be said of them, only that in persons who live very freely and 

 drink much wine, they are apt to become affected with gout ; and 

 in elderly people the joint at the ball of the great toe is liable to 

 be drawn so as to make a projection on the inner side of the 

 foot, become exposed to pressure from the shoe, and produce 

 corns. 



The most common disease of joints is their inflammation. Some- 

 times this is acute, as after injuries or from rheumatism. The 

 synovial bag becomes inflamed, and forms an inordinate quantity of 



