28 ANATOMY AND PHYSIOLOGY 



Clinical note. Dislocation of this joint easily occurs if the 

 mouth is opened too widely. 



The angle of the jaw or mandible, is the posterior extremity of the lower 

 border. The prominence of the angle differs in different people and at 

 different ages. 



ARTICULATIONS OF THE FACE 



The bones of the face are all irregular, and many of them are 

 very frail. They are fixed by sutures with one exception that 

 of the mandible which moves freely. (For description of a 

 movable joint, see page 17.) 



THE MANDIBULAR JOINT 



The mandibular joint is a hinge-joint, and the only movable 

 joint in the skull. The action may be felt in front of the ear. 



The bony surfaces are the condyle of the mandible and the 

 mandibular fossa of the temporal bone. They are covered with 



Capsule 



FIG. 19. MANDIBULAR JOINT. (After Morris.) 



cartilage and connected by ligaments forming a capsule, which is 

 sufficiently loose to allow the condyle to glide freely in the fossa, 

 back and forth or sidewise, as in opening and closing the mouth 

 and masticating the food. 



Surgical notes. If the mouth be suddenly opened very 

 widely, as in hearty laughing, dislocation easily results that is, 



