STNOVIAL JOINTS. 95- 



fche joint, and another is the round ligament, which passes 

 from the acetabulum to the head of the femur. Should 

 the latter rotate above a certain extent in its socket, the 

 round ligament and one side of the capsular ligament are 

 put on the stretch, and any further movement which might 

 dislocate the femur (that is remove the head from its 

 socket) is checked. Covering the inside of the capsular 

 ligament and the outside of the round ligament is a layer 

 of flat cells, which are continued in a modified form over 



FIG. 40. Section through the hip-joint. 



the articular cartilages and form the synovial membrane* 

 This, which thus forms the lining of the joint, is always 

 moistened in health by a small quantity of glairy synovial 

 fluid, something like the white of a raw egg in consis- 

 tency, and playing the part of the oil with which the con- 

 tiguous moving surfaces of a machine are moistened; it 

 makes all run smoothly with very little friction. 



In the natural state of the parts, the head of the femur 

 and the bottom and sides of the acetabulum lie in close 

 contact, the two synovial membranes rubbing together. 



