A MANUAL OF DENTAL ANATOMY. 



canals to the incisors, not traceable far. It is nearer to the 

 outer than to the inner surface of the jaw in the latter half 

 of its course, and is apt to be very close to the ends of the 

 roots of the wisdom teeth, and to those of the bicuspids. 

 The alveolar processes of the lower jaw, at their posterior 

 part, diverge more widely than those of the upper jaw, the 

 relative antagonism between the upper and lower teeth 

 being preserved in this region b}' the former having an in- 

 clination outwards, the latter inwards. The ascending rami 

 join the body at an angle which is very obtuse in the foetus, 

 nearly a right angle in the adult, and once again obtuse in 

 advanced old age ; the explanation of this change will be 

 given under the head of the Development of the Jaw. 



The articulation of the human lower jaw is peculiar, and 

 allows of a degree of play unusual in a joint. The ovoid 

 condyles, when the jaw is at rest, are lodged in depressions, 

 the glenoid fossae of the temporal bone, formed partly by the 

 squamous and partly by the vaginal portions of the bone. 

 The posterior half of the cavity is rough, and lodges a portion 

 v of the parotid gland : the anterior is smooth, and is bounded 

 in front by the eminentia articularis, which is the middle 

 root of the zygoma, enters into the formation of the joint, 

 and is coated over by cartilage. Between the condyle of the 

 lower jaw and the temporal bone lies a moveable inter- 

 articular Jibro -cartilage, which is an irregular bi-concave oval 

 plate, the edges of which are united with the capsular liga- 

 ment, so that the joint is divided into two cavities, furnished 

 with separate synovial membranes (unless when, as some- 

 times is the case, the fibro-cartilage is perforated in its 

 centre). 



The joint is described as having four ligaments : the 

 capsular, stylo-maxillary, internal and external lateral 

 ligaments. 



The capsular ligament is but feebly pronounced, and 

 hardly deserves the name ; the stylo-maxillary reaches from 



