THE CRANIAL OR ENCEPHALIC NERVES. 715 



similar to those of the superior maxillary nerve, and named the mental 

 nerves. 



For the first third of its extent, the inferior maxillary nerve is a flattened 

 band ; but beyond this it becomes thicker, and acquires a funicular shape. 



At its origin it gives rise to four branches : 



1. The masseteric nerve. 



2. The buccal nerce. 



3. The nerve of the internal pterygoid muscle. 



4. The superficial temporal or subzygomatic nerve. 



After its emergence from between the two pterygoid muscles, it furnishes : 



5. The gustatory nerve. 



6. The mylo-hyoid nerve. 



In its intermaxillary course, it detaches : 



7. The dental branches. 



Also a triple series of collateral nerves which we will study before 

 describing the terminal branches ; these are : 



8. The mental nerves. 



The trunk of the inferior division of the fifth pair represents a mixed 

 nerve, because it is formed of sensitive and motor fibres. Is it the same for 

 each of the branches just enumerated ; that is, do they all contain fibres of 

 the two orders ? This is a question on which the dissection of the two 

 roots has taught us very little, for their fibres soon become confounded so 

 intimately that it has always been found impossible to follow them separately 

 into each nerve. But the study of the distribution of these branches, corrobo- 

 rated by physiological experiments, has greatly enlightened us in this 

 inquiry. We see among them nerves destined to the muscles, and others 

 to glandular or integumental structures; the first are therefore chiefly 

 composed of motor fibres, like all other muscular nerves ; and the second 

 exclusively contain sensitive fibres, or at least are deprived of voluntary 

 motor fibres. In describing each branch in particular we will notice 

 their special properties. 



1. MASSETERIC NERVE (Figs. 336, 9 ; 342, 2). It is detached from the prin- 

 cipal trunk, in front, though close to, the base of the cranium, bends round 

 the anterior face of the temporo-maxillary articulation, and passes through 

 the sigmoid notch of the inferior maxilla to descend into the texture of the 

 masseter muscle and there ramify. 



At its origin, this nerve furnishes two filaments which often proceed 

 from one very short trunk, and ascend into and expend themselves in the 

 temporal muscle ; this trunk is then the deep posterior temporal nerve. 



Before crossing the corono-condyloid notch, it detaches to this same 

 temporal muscle a small branch which represents the deep middle temporal 

 nerve. 



The destination of all these branches sufficiently proves that they are 

 motor. 



2. BUCCAL NERVE (Figs. 336, 14 ; 342, 4). This nerve, which is twice the 

 size of the preceding, arises from the same point, though slightly below it. It 

 is directed forwards, traverses the external pterygoid muscle, and reaches the 

 posterior extremity of the superior great molar gland ; leaving which, it is 

 placed beneath the buccal mucous membrane, and descends to the commissure 

 of the lips, along the inferior molar gland and the inferior border of the 

 alveolo-labialis muscle. 



