THE CRANIAL NERVES. 539 



meatus, the side o the head, the mucous membrane of the 

 mouth, the anterior portion of the tojague, the arches of the 

 palajje, the teeh~and alveolar process of the lower jaw and the 

 integument of the lower part of the face (Fig. 250). 

 Cortical Connections. The nerve-cells around which the end- 

 tufts of the centrally coursing axons ramify collectively constitute 

 the " sensor end-nuclei " of the trigeminal nerve. From these cells 

 new axons arise which cross the median line, enter the fillet or 

 lemniscus, and ascend directly to the sensor area of the cerebral 

 cortex. 



Properties. Irritative pathologic lesions, e. g., pressure by 

 tumors, aneurysms, neuritis, degenerative changes in the ganglion 



FIG. 249. i. Superior maxillary nerve. 2, 3, 4, 5. Dental nerves. 6. Spheno- 

 palatine ganglion. 7. Vidian nerve. 8. Large superficial petrosal. 9. Carotid 

 branch of large petrosal. 10. Oculo-motor. n. Superior cervical ganglion. 12. 

 Carotid branches of this ganglion. 13. Facial. 14. Glosso-pharyngeal. 15. 

 Jacobson's nerve, and 16, 17, 18, 19, branches to the sympathetic, fenestra 

 rotunda, Eustachian tube. 20. Deep external petrosal. 21. Deep internal 

 petrosal. 



cells, or lesions which in any way gradually impair the physical or 

 chemic integrity of the nerve-fibers, give rise to a variety of painful 

 sensations referable to the seat of the lesion or to one or more regions 

 in the peripheral distribution of the nerve. Many of the various 

 forms of trigeminal neuralgia are caused by lesions of this character. 

 Exposure of the dental nerves from caries of Jhe teeth,jbhe presence 

 of rmnule foreign bodies in the conjunctiva, operative procedures in 

 the nasal chambers, all testify to the extreme sensibility of the nerve. 

 Division of the large root within the cranium is followed at once by 

 complete abolition of all sensibility in the head and face to which 

 its branches are distributed. The skin and mucous membranes, the 

 eye, nose, or teeth may be experimentally injured without any evi- 



