DISEASES OF THE NEBVOUS SYSTEM. 115 



side of the cerebellum to the other. Anterior to the pons Varolii are 

 two white bundles the crura cerebri. Their continuation with the 

 medulla oblongata is covered by the pons Varolii; anteriorly they run 

 "i 1 1 1< > the cerebral hemispheres. At th e anterior part of the fissure which 

 separates the crura cerebri is the pituitary gland and the tuber cincrcum. 

 From the under surface of each of the cerebral hemispheres proceeds 

 anteriorly an appendage called the olfactory lobe. 



The arrangement of the gray and white substances of the brain is, to 

 a great extent, the reverse of that of the spinal cord, the gray being 

 external and the white internal, except as regards the medulla ob- 

 longata. in which the gray matter forms centers in its substance. 



The average weight of the .brain in cattle as compared to the weight 

 of the entire body, is estimated as 1 to 860; or, in other words, if the 

 weight of the animal be 860 pounds, the weight of the brain will be 1 

 pound. 



The cranial nerves are given oft* by the brain; they are in pairs, as 

 follows: (1) Olfactory the nerves of the special sense of smell. (2) 

 Optic the nerves of the special sense of sight. (3) Oculo-motor sup- 

 ply impulse to all the muscles which move the eyeball, except three. 

 (4) Pathetic! motor nerve to the muscle which rotates the eyeball in- 

 ward and upward. (5) Trifacial nerves of various functions. They 

 are in three divisions and each division has numerous branches. The 

 ophthalmic division supplies sensation to the eye and forehead. The 

 superior maxillary division supplies sensation to the skin of the face, to 

 tin- membrane within the nose, and gives to the teeth in the upper jaw 

 tin-ir M-ii^itiwui-^. Tin- in'--i ir in t\ill,i!y !ivi>ion supplies BensatUH 

 to the teeth in the lower jaw, to the tongue, mouth, and the skin over 

 the lower jaw. Some of the fibers of this pair aid in supplying the spe- 

 rm I sense of taste. This pair also supplies motor fibers to the muscles 

 which move the jaw in the act of mastication. (6) Abducentes motor 

 nerve to the muscle which turns the eyeball outward. (7) Facial sup- 

 plies motor impulses to various muscles about the head. (8) Auditory 

 the nerves of the special sense of hearing. (9) Glosso-pharyngeal 

 contains motor and sensory fibers to the tongue and pharynx. It also 

 supplies fibers to aid in the special sense of taste. (10) Piuuimogjvs- 

 tric sends fibers to the pharynx, larynx, trachea, bronchi, lungs, eso- 

 phagus, stomach, heart, and many other parts. Its functions are 

 numerous and important, being both motor and sensory. A branch 

 gives to the mucous membrane of the larynx its extraordinary sensi- 

 tiveness, while another branch supplies motor impulse to the muscles 

 of the larynx. Another branch is the inhibitory nerve of the heart. 

 Other branches are, thought to participate in exciting the production of 

 the gastric juice and the bile. The pncumogastric is connected at dif- 

 ferent parts with the sympathetic division. (11) Spinal accessory 

 motor nerves, accessory to the pneumogostric. (12) Hypoglossal motor 

 nerves of the tonjnie, and some fibers to a few other muscles. 



