36 ELEMENTARY PHYSIOLOGY 



deepen the bony sockets of various joints by surrounding them at 

 their edges in the form of a ring. The sockets thus deepened are 

 better enabled to hold the rounded heads of the bones which 



Fig. 39. Interior Surface of the Parietal Bone, 



Showing the irregular, notched edges of the suture. 



Fig. 40. Section of the Bight Foot, 



Showing the nature of a sliding or gliding joint, synovial membranes, and synovial cavities ; 



also ligament and tendon. Showing also the arched form of the foot. 



t t 2j 3j 6, 7, 8, and 10, synovial cavities, surrounded by synovial membrane ; 4 and 5, liga- 

 ments ; 9, tendon. 



move in them, and, the cartilage being flexible and elastic, the 

 motion is not restricted. Cartilage also lines the surfaces of bones 



