TBR CRANIAL OH ENCEPHALIC NERVES. 819 



between the two pterygoid muscles, then between the inner and deep face of the 

 maxiUa, arriving at the inferior dental foramen, througii which it passes and 

 runs along the whole coui-se of the canal, escaping at last by the mental foramen 

 to form an expansion of terminal branches similar to those of the supcirior 

 maxillary Tierve, and named the mental nerves. 



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

 band ; hut heyoud 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 nerve. 



3. The /lerre of the internal pterygoid muscle. 



4. The superficial temporal or subzjjqomatic nerve. 



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



5. The gustatory nerve. 



6. The mylo-hgoiihan 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 : this 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 til»res 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, corroborated 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 structm-es ; 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 destitute of voluntary 

 motor fibres. In describing each branch in particular, we shall notice their 

 special properties. 



1, Masseteric Nerve (Fig. 453, 9 ; 459, 2). — It is detached from the prin- 

 cipal trunk, in front of, 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 to 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. 453, 14 : 459, 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 and great molar gland ; leaving this, it is 

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



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