208 ANATOMY FOR NURSES. [CHAP. XVIII. 



1. Olfactory. 7. Facial. 



2. Otpic. 8. Auditory. 



3. Motor oculi. 9. Glosso-pharyngeal. 



4. Pathetic. 10. Pneumo-gastric. 



5. Trifacial. 11. Spinal-accessory. 



6. Abducens. 12. Hypo-glossal. 



The first or olfactory nerve is the special nerve of the sense 

 of smell. It arises by three roots from the interior of the brain, 

 and sends numerous fibres through the perforated plate of the 

 ethmoid bone, to be distributed to the mucous membrane lining 

 the nasal chamber. 



The second or optic nerve is the special nerve of the sense of 

 sight. It enters the orbit and is distributed to the interior of 

 the eyeball. Before entering the orbit the nerve is connected 

 with its fellow of the opposite side by a band or commissure, 

 and from this union it may be traced back along the optic tract 

 to its deep origin in the central gray matter of the brain. 



The third or motor oculi nerve is the chief mover of the eye ; 

 it supplies all the muscles of the eye with the exception of the 

 superior oblique and external rectus. Its origin may be traced 

 back to the gray matter in the medulla oblongata. 



The fourth or pathetic nerve, the smallest of the cranial 

 nerves, supplies the superior oblique muscle of the eye. It 

 arises close to the third nerve. 



The fifth or trifacial nerve is the largest of the cranial nerves. 

 It arises by two roots, a posterior or sensory, and an anterior 

 or motor. The posterior root is larger than the anterior, and 

 has a ganglion developed on it. The fibres from the two roots 

 coalesce into one trunk, and then subdivide into three large 

 branches: the ophthalmic, the superior maxillary, and the 

 inferior maxillary. The ophthalmic branch is the smallest, and 

 is a sensory nerve. It supplies the eyeball, the lachrymal gland, 

 the mucous lining of the eye and nose, and the skin and mus- 

 cles of the eyebrow, forehead, and nose. The superior maxil- 

 lary, the second division of the fifth, is also a sensory nerve and 

 supplies the skin of the temple and cheek, the upper teeth, and 

 the mucous lining of the mouth and pharynx. The inferior 

 maxillary is the largest of the three divisions of the fifth, and is 

 both a sensory and motor nerve. It sends branches to the tem- 

 ple and the external ear; to the teeth and lower jaw; to the 



