240 



THE CRANIAL NERVES. 



in the malar bone. While still in the orbit, it is joined by a communicating filament 

 (in some cases by two filaments) from the . lachrymal nerve. The nerve is then 

 inclined upwards in the temporal fossa between the bone and the temporal muscle, 

 and perforating the aponeurosis over the muscle nearly an inch above the zygoma, 

 ends in cutaneous filaments over the fore part of the temporal region. The 

 cutaneous ramifications are united with the facial nerve, and sometimes with the 

 auriculo-temporal branch of the third division of the fifth. 



(#) The malar branch (r. zygomalicofacialis) lies at first in the loose fat in the 

 lower angle of the orbit, and is continued to the face through the malar canal of the 

 malar bone, where it is frequently divided into two filaments. It is distributed to 

 the skin over the malar bone, after forming a communication with the facial nerve. 



Varieties. The temporo -malar nerve is subject to frequent deviations from the arrange- 

 ment above described. Thus, either branch may be smaller than usual, or even absent, in 

 which case the other division of the nerve may be distributed over a larger area, or the 

 temporal branch may be reinforced or replaced by the lachrymal nerve, the malar branch by 

 the infraorbital nerve. The temporal branch, instead of perforating the malar bone 

 frequently passes into the temporal fossa through the anterior end of the spheno-maxillary 

 fissure. 



The superior dental or alveolar nerves are, as a rule, three in number, 

 anterior, middle, and posterior, but the middle is sometimes conjoined with the 

 anterior, while the posterior is frequently represented by two separate offsets. 



Fig. 159. DEEP VIEW OF THE 



SUPERIOR MAXILLARY 



SERVE AND THE SPHF.XO- 

 PALATINE GANGLION, &C, 



(From Sappey, after 

 Hirschfeld and Leveille.) 

 I 



1, superior maxillary 

 nerve ; 2, posterior superior 

 dental ; 3, middle superior 

 dental ; 4, anterior superior 

 dental ; 5, superior dental 

 plexus ; 6, spheno-palatine 

 ganglion ; 7, Vidian nerve ; 

 8, its great superficial petrosal 

 branch ; 9, its great deep 

 petrosal branch ; 10, a part 

 of the sixth nerve, receiving 

 twigs from the carotid plexus 



of the sympathetic ; 11, superior cervical sympathetic ganglion ; 12, its ascending branch ; 13, facial 

 nerve; 14, glosso-pharyngeal nerve ; 15, its tympanic branch ; 16, carotico-tympanic twig joining the 

 sympathetic ; 17, filament to the fenestra rotunda ; 18, filament to the Eustachian tube ; 19, filament 

 to the fenestra ovalis ; 20, small superficial petrosal nerve. 



The posterior superior dental nerve arises from the superior maxillary trunk before 

 it enters the infraorbital groove, and immediately divides into two branches (often 

 separate at their origin), which descend with the posterior dental artery on the 

 zygomatic surface of the upper jaw. They send small external filaments to the gum 

 and the adjacent part of the mucous membrane of the cheek, and then enter the 

 posterior dental canals to terminate in offsets to the molar teeth and the lining 

 membrane of the antrum. 



Variety. The posterior dental nerve has been seen in a few instances of large size, and 

 replacing the buccal nerve, which was absent as a branch of the inferior maxillary, in the 

 supply of the cheek. 



