SENSE ORGANS. 589 
cinereum or infundibulum), to which the pituitary body 
_ is attached. : 
The optic lobes, a pair of oval bodies, between and 
below which is the iter. 
The cerebellum, a very narrow transverse band. 
The medulla oblongata, on the roof of which the pia 
mater forms a very vascular “ choroid plexus.” 
The cavities of the brain and the canal of the spinal cord 
are in the adult lined by ciliated epithelium. _ 
The cranial nerves are, as usual, on each side the 
following :— 
(1) Olfactory, from the olfactory lobe to the nose ; 
(2) Optic, crossing and interlacing with its fellow ; 
(3) Oculomotor, to four muscles of the eye ; 
(4) Pathetic, to the superior oblique eye muscle ; 
(5) Trigeminal, with ophthalmic, maxillary, and mandibular branches ; 
(6) Abducens, to the external rectus eye muscle ; 
(7) Facial, arising along with the auditory, with a ganglion uniting 
with the Gasserian ganglion of,the trigeminal, with a palatine 
branch to the roof of the mouth, and a hyoid branch to the 
lower jaw ; 
(8) Auditory, to the ear ; 
(9) Glossopharyngeal, to the tongue and some of its muscles; with 
a ganglion which unites with that of the tenth ; 
(10) Vagus, with branches to lungs, heart, stomach, etc. 
The spinal cord gives origin to ten pairs.of spinal nerves, and is 
swollen at the origin of those which go to the limbs. Around the 
union of the anterior and posterior roots lie sacs with crystals of 
carbonate of lime. 
The sympathetic system consists of about ten pairs of ganglia—(a) 
united by branches to the spinal nerves; (4) united to one another by 
longitudinal trunks which accompany the dorsal aorta and the systemic 
arches, and end anteriorly in the Gasserian ganglion; (c) giving off 
branches to the heart, the aorta, and the viscera in the pelvic region. 
Sense organs.—The eyes project on the top of the head 
and on the roof the mouth. There is a third eyelid. 
The transparent cornea in front, the firm sclerotic surround- 
ing the eyeball, and the sheath of the optic nerve, are as 
usual continuous. The next layer includes the vascular 
and pigmented choroid and the brilliant iris. Internally is 
the sensitive retina, while vitreous humour fills the cavity 
behind the lens. 
The internal ears have the usual parts, and lie within the 
auditory capsules, which are in great part bounded by the 
