1 84 



THE NERVOUS SYSTEM 



the extrinsic muscles of the eye. Johnston (1909) has shown that the large 

 unipolar cells of the mesencephalic nucleus of the fifth neroe which give rise 



Fig. 131. Diagram of the nuclei and central connections of the trigeminal nerve: A, Semi- 

 lunar ganglion; B, mesencephalic nucleus, N. V.; C, motor nucleus, N. V.; D, motor nucleus, N. 

 VII E, motor nucleus, N. XII ; F, nucleus of the spinal tract of N. V. ; G, sensory fibers of the sec- 

 ond order of the trigeminal path: a, ascending and b, descending branches of the sensory fibers, 

 N. V.; c, ophthalmic nerve; d, maxillary nerve; e, mandibular nerve. (Cajal.) 



to the fibers of the mesencephalic root of that nerve, are probably sensory in 

 function. Willems (1911) and Allen (1919) believe that these are sensory fibers 



