CEREBROSPINAL NERVES. 
371 
the first pair are the olfactive , which proceed from the bulbs 
(1) of the olfactive peduncles, into the cavity of the nose. 
Next to these are the optic nerves (2), which may be partly 
traced to the optic ganglia, and i a & 
partly to the thalami optici. The 2 
third (3), fourth (4), and sixth pairs 
(6), are nerves of motion only, and 
are distributed to the muscles of 
the eye. The fifth pair is for the 
most part a nerve of sensation 
only. Before leaving the skull, it 
divides into three great branches; 
of which the first (5) passes into 
the orbit (or cavity in which the 
eye is lodged), endows the parts 
contained in it with sensibility, 
and then comes out beneath the 
eyebrow, to be distributed to the 
forehead and temples ; the second 
ip') passes just beneath the orbit, 
and makes its way out upon the 
face, supplying the cheeks, nose, 
upper lip, &c., which it endows 
with sensibility; whilst the third 
(5"), which (like the spinal nerves) 
possesses a motor root also, supplies 
the muscles of mastication with 
the power of moving, and the 
parts about the mouth with sensi¬ 
bility. The seventh pair (7), or 
facial, is the general motor nerve 
of the face; and this does not 
endow the parts which it supplies 
with the least sensibility. Beneath 
the origin of this nerve is seen the 
cut extremity of another trunk, 
that of the auditory nerve (8), or 
nerve of hearing. At 9 is seen the glosso-pharyngeal nerve, 
which supplies the back of the mouth and pharynx, and is 
concerned in the act of swallowing. Originating from the 
upper part of the spinal cord (or medulla bloongata) very near 
b b 2 
Fig. 197.— Brain and Spinai 1 
Cord op Man. 
