THE CRANIAL NERVES. 



523 



become related by means of their end-tufts with primal 

 ganglia. 



The nerves^ of general sensibility have their origin in the ganglia 

 on their trjjflKs. and in this respect resemble the spinal nerves. FroST 

 ion cell there emerges a short axon process which soon 

 divides into a central and a peripheral branch. The former passes 

 toward and into the gray matter located beneath the floor of the 

 fourth ventricle, where its end- 

 tuf ly ar"b<3f!ze about nerve-cells. 

 The latter (the peripheral branch) 

 passes toward the general periph- 

 ery to be distributed to skin and 

 mucous membranes (Fig. 236). 



The nerves of motion have 

 their origin in trie nerve^ells in 

 the gray jnatter beneath the 



agnprhirf nf Sylyjyp anH IwipatVi 

 the floor Of tljfi fom*h vpntnVlp 



(Fig. 237). The axons emerging 

 from these cells course per- 

 ipherally to be distributed to 

 skeletal muscles. In some of the 

 motor nerves, and in some 

 sensory nerves as well, there are 

 to be found efferent fibers of 

 smaller size which have a similar 

 origin and which become related 

 through the intervention of 

 sympathetic ganglia (peripheral 

 neurons) with visceral muscles 

 and glands. These nerves have 

 been termed autonomic nerves. 



The Cerebral Connections 

 of the Cranial Nerves. Each 

 of these three groups of cranial 

 nerves has special connections 

 with the cerebral cortex. 



The nerves of sp_ecial_sense for the most part terminate in primary 

 basal ganglia, around theTcells of which their central end-tufts ar- 

 borize. Fromjhe.se cells a fflflfi arise which pass upward and directly 

 or indirectly come into physiologic relation with sensor nerve-cells 

 in the cerebral cortex. 



The nerves of general sensibility terminate in the gray matter 

 beneath thejlcx)r_j)j^^ around the nerve-cells of 



wrnclTTGeir end-tufts arborize. These groups of nerve-cells are 



FIG. 235. SUPERFICIAL ORIGIN or THE 

 CRANIAL NERVES FROM THE BASE 

 OF THE ENCEPHALON. i. Olfactory. 

 2. Optic. 3. Motor oculi. 4. 

 Patheticus. 5. Trigeminal. 6. Abdu- 

 cens. 7. Facial. 7'. Nerve of 

 Wrisberg. 8. Auditory. 9. Glosso- 

 pharyngeal. 10. Pneumogastric. 

 ii. Spinal accessory. 12. Hypo- 

 glossal. 



