86 FORM AND ACTION. 



must have been furnished with the deep socket and complete re- 

 ception of the ball into it, which we observe in the articulation now 

 under our consideration. 



A beautiful contrivance, however, in defence of dislocation, 

 whether it be likely to happen from the extensive motion enjoyed 

 by the hip joint, or from the resistance it opposes to the force of 

 the weight and shocks it receives, is the round ligament, as it has 

 been named ; a ligament or round cord, characteristically short 

 and strong, one end of which is affixed to the centre of the spherical 

 head of the os femoris, while its other end is rooted into the floor 

 of the socket in which that head plays : thus in nowise interfering 

 with the revolutions and turnings of the ball within its socket — in 

 nowise limiting or abridging the movements of the hind limb, 

 and yet most effectually, in all those varied movements, preserving 

 the hip joint from dislocation. By the depth of the acetabulum, 

 for so the socket in the pelvis is called — which in the recent sub- 

 ject is still further deepened by an edging of cartilage or gristle, 

 whose flexibility admits of all the required latitude of motion ; by 

 the round ligament; and by the thick and powerful muscles by 

 which it is on every side invested, is the hip joint preserved 

 from displacement : indeed, without rupture or laceration of the 

 round ligament it is impossible for dislocation to take place. 



Another remarkable feature in the os femoris is the huge ill— 

 shapen projection proceeding from its upper and posterior part, 

 which has got the name of greater trochanter, by way of dis- 

 tinguishing it from a process much less in magnitude arising from 

 the body of the bone. This protuberant portion of bone may be 

 regarded in the light of an elbow, or a hock, or any other pro- 

 jection whose use is to serve as a lever of the most favourable 

 description, compatible with the situation it is in and to the muscles 

 to be attached to it. Into the great trochanter are inserted those 

 powerful muscles which extend the haunches after they have been 

 flexed and advanced underneath the body, and in this act of exten- 

 sion propel the machine forward : no wonder, therefore, that it 

 should have been constructed, in respect to magnitude and posi- 

 tion, in a manner to offer the greatest possible leverage. When we 

 see the quarters straight and lengthy, and the stifles prominent 

 and jutting well forwards, we may take it for granted that the 



