THE FIFTH NERVE, OR TRIGEMINAL 



6i 3 



serian ganglion. The nerve appears at the ventral surface of the pons 

 near its front edge, at some distance from the mid-line. 



Motor Functions. The first and second divisions of the nerve, which 

 arise wholly from the larger root, are purely sensory. The third division is 

 joined by the motor root of the nerve and is of course both motor and sensory. 



Motor branches of the lesser or non-ganglionic portion of the fifth supply 

 the muscles of mastication, namely, the temporal, masseter, two pterygoid, 

 anterior part of the digastric and mylohyoid. Filaments are also said to 

 supply the tensor tympani and tensor palati (Kolliker). The motor func- 



VM. 



FIG. 410. Section Across the Pons, About the Middle of the Fourth Ventricle, py, 

 Pyramidal bundles; po, transverse fibers passing po l , behind, and po 2 , in front of py; r, 

 raphe; o.s, superior olive; a.V, bundles of ascending root of V. nerve enclosed in a pro- 

 longation of the substance of Rolando; VI, the sixth nerve; nVI, its nucleus; VII, facial 

 nerve; VII. a, intermediate portion; nVII, its nucleus; 77/7, auditory nerve, nVIII, 

 lateral nucleus of the auditory. (After Quain.) 



tion of these branches is proved by the violent contraction of all the muscles 

 of mastication in experimental irritation of the third or inferior maxillary 

 division of the fifth nerve; by paralysis of the same muscles when the nerve 

 is divided or disorganized; and by the retention of the power of these muscles 

 when the facial nerve is paralyzed. Whether the branch of the fifth nerve 

 which is supplied to the buccinator muscle is entirely sensory, or in part 

 motor also, must remain for the present doubtful. From the fact that this 

 muscle, besides its other functions, acts in concert or harmony with the 

 muscles of mastication in keeping the food between the teeth, it might be 

 supposed from analogy that it would have a motor branch from the same 

 nerve that supplies them. However, the so-called buccal branch of the fifth 

 is, in the main, sensory. 



Sensory Functions. All the anterior and antero-lateral parts of the face 



