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TEXT-BOOK OF PHYSIOLOGY. 



the pons each axon divides into two branches, one of which passes upward 

 a short distance, the other passes downward, descending as far as the 

 second cervical segment. Both branches give off a number of collaterals, 

 some of which terminate in fine end-tufts around nerve-cells in the sub- 

 stantia gelatinosa. 



2. The Peripheral Branches. The peripheral axons emerge from the 

 peripheral end of the ganglion of Gasser in three distinct and separate 

 branches, each of which is distributed to a different region of the face 

 and head. 



i. The ophthalmic branch passes forward and subdivides into three large 

 branches, the frontal, the lachrymal, and the nasal. The ultimate 



termination of the branches of 

 these nerves is as follows: viz., 

 the conjunctiva and skin of the 

 upper eyelid, the cornea, the skin 

 of the forehead and the nose, the 

 lachrymal gland and caruncle, 

 and the mucous membrane of 

 the nose (Fig. 273). 

 2. The superior maxillary branch 

 passes forward through the fora- 

 men rotundum, crosses the 

 spheno-maxillary fossa, enters 

 the infra-orbital canal, and emer- 

 ges at the infra-orbital foramen. 

 In its course it gives off a num- 

 ber of branches which are dis- 

 tributed as follows: viz., to the 

 integument and conjunctiva of 

 the lower lid, the nose, cheek, 

 and upper lip, the palate, the 

 teeth of the upper jaw, and the 

 alveolar processes (Fig. 274). 

 3. The inferior maxillary branch passes through the foramen ovale, after 

 which it subdivides into three branches the auriculo-temporal, the 

 lingual, and the inferior dental. The ultimate branches are distributed 

 as follows: viz., the external auditory meatus, the side of the head, the 

 mucous membrane of the mouth, the anterior portion of the tongue, the 

 arches of the palate, the teeth and alveolar process of the lower jaw and 

 the integument of the lower part of the face (Fig. 275). 

 The afferent axons thus serve to bring into relation the skin, mucous 

 membranes of the head and face, and other sentient structures, with certain 

 sensor end-nuclei in the pons, medulla oblongata, and adjoining structures. 

 Cortical Connections. The afferent portion of the trigeminal nerve 

 is brought into physiologic relation with the sensor portion of the cerebral 

 cortex by means of nerve-fibers which have their origin in the cells around 

 which the terminal branches of the centrally coursing fibers arborize. The 

 cells situated in the substantia gelatinosa give off axons, which after a short 

 course cross the median line, enter the fillet and then ascend in the general 



FIG. 273. OPHTHALMIC BRANCH OF THE 

 FIFTH, i. Ganglion of Gasser. 2. Oph- 

 thalmic division of the fifth. 3. Lachrymal 

 branch. 4. Frontal branch. 5. External 

 frontal. 6. Internal frontal. 7. Supra- 

 trochlear. 8. Nasal branch. 9. External 

 nasal. 10. Internal nasal. (Hirschjeld.) 



