98 SURGICAL APPLIED ANA TOMY. [Chap. VIL 



pterygoid muscle (the muscle mainly answerable for 

 the luxation) contract vigorously, the condyle is soon 

 drawn over the eminence into the zygomatic fossa, the 

 interarticular cartilage remaining behind. On reaching 

 its new position it is immediately drawn up by the 

 temporal, internal pterygoid, and masseter muscles, and 

 is thereby more or less fixed. A specimen in the 

 Musee Dupuytren shows that the fixity of the 

 luxated jaw may sometimes depend upon the catching 

 of the apex of the coronoid process against the malar 

 bone. 



Excision of the inferior maxilla. Con- 

 siderable portions of the lower jaw can be excised 

 through the mouth without external wound. In 

 excising one entire half of the maxilla a cut is made 

 vertically through the lower lip down to the point of 

 the chin, and is then continued back along the inferior 

 border of the jaw, so as to end near the lobule of 

 the ear, after having been carried vertically upwards 

 in the line of the posterior border of the ramus. The 

 soft parts divided may be considered under three 

 heads : (1) Those concerned in the first incision ; (2) 

 in clearing the outer surface of the bone ; (3) in 

 clearing the inner surface of the bone. 



1. (a) In the anterior vertical cut : Skin, etc., 

 orbicularis oris, inferior coronary and inferior labial 

 vessels, branches of submental artery, levator menti, 

 mental vessels and nerve, some radicles of anterior 

 jugular vein. (5) In the horizontal cut : Skin, etc., 

 platysma, branches of superficial cervical nerve, 

 branches of supramaxillary part of facial nerve, facial 

 artery and vein at edge of masseter, and inframax- 

 illary branch of facial nerve (not necessarily divided). 

 i (c) The posterior vertical incision would not go down 

 to the bone, and would merely expose the surface of the 

 parotid gland, and part of posterior border of masseter 

 muscle. 



