184 WILLIAM F. ALLEN 



buccinatorius (fig. 3, Biic.) happens to be the most cephaUc 

 branch of the masticator nerve. Curving around the inner 

 surface of the temporal muscle, it enters the floor of the orbit a 

 little median to the pterygoid nerve, where it branches ventrally 

 to supply the mouth cavity. Serial sections from experiment 

 no. 65 show no degenerated motor fibers in this nerve. Two 

 Nn. temporales profundi appear directly behind the buccal nerve 

 to innervate the temporal muscle. Only one of these nerves, 

 the larger and most peripheral, is shown in figure 3 (Tern.). 

 Immediately behind the deep temporal nerves there is a larger 

 branch of the masticator, designated as the N. pterygoideus 

 (fig. 3, Pter.). This nerve assumes a lateral and cephalic course, 

 passing between the mandible and temporal muscle, enters the 

 floor of the orbit a little lateral to the buccal nerve, and following 

 along the dorsal surface of the pterygoid muscles, sends numerous 

 branches to them. Before entering the orbit it gives off a branch 

 to the masseter muscle. Some text-books on mammalian anatomy 

 describe a similar nerve as the N. buccinatorius, but the nerve 

 described above is purely a motor nerve, producing a contraction 

 of the pterygoid muscles upoiLstunulation, and series no. 65 shows 

 that it is full of degenerated motor nerve fibers. The N. masse- 

 tericus (fig. 3, Mas.) is the last branch of the masticator nerve. 

 It is fully as large as the pterygoid nerve and. at first pursues a 

 lateral cephalic course immediately behind the pterygoid nerve, 

 and upon reaching the outer surface of the mandible, breaks up 

 into several branches for the masseter muscle. Like the ptery- 

 goid and deep temporal nerves, it is purely a motor nerve as 

 was shown by stimulation, and in tracing this nerve peripherally 

 in series no. 65, branches containmg degenerated motor fibers 

 can be traced to masseter muscle fibers (fig. 30, Mas.). 



To return to figure 3, where the purely sensory nerves are 

 drawn in outline and the motor nerves are cross-barred, it will 

 be seen that the ophthalmic and maxillary divisions of the tri- 

 geminus are sensory and the mandibular division is mixed. Of 

 the three components of the mandibular, the masticator nerve is 

 mainly motor (see previous footnote excluding muscle sense from 

 this statement), only the small buccal branch being sensory; the 



