THE NERVOUS SYSTEMo 115 



deep origin in the medulla oblongata, although the superficial 

 origin of some of them is some distance off. 



THE FIRST PAIR are known as the olfactory., or nerves of 

 smell. They pass out through the roof of the nose, and are 

 distributed to the lining of the nostrils. 



THE SECOND PAIR, or optic nerves, are distributed to the 

 eye-balls, and are the nerves of vision. These nerves do not 

 pass directly forward, one to each eye, but cross fibres with 

 each other before they leave the skull, making PJ close union 

 between the eyes. 



THE THIRD PAIR, THE FOURTH PAIR AND TH73 SIXTH PAIR 



supply the various muscles by which the eyes are moved. 

 These are called the motores oculi. 



THE FIFTH PAIR are called the trifacial, on account of each 

 dividing into three branches. These are the largest nerves 

 given off from the brain, and supply the skin of the face and 

 some of the deeper parts, such as the teeth, roof of mouth, 

 soft palate, tongue, etc. One branch supplies the sense of 

 taste. It is usually some of the branches of these nerves that 

 are affected in people who suffer from neuralgia of the face 

 and tooth-ache. 



THE SEVENTH PAIR, or facial, are the moving nerves of all 

 the muscles of expression in the face. They usually work 

 in perfect unisqn and cause the muscles to draw evenly, as in 

 laughing, singing, whistling, etc. When one of these nerves 

 is paralyzed it gives a very odd expression to the face. 



THE EIGHTH PAIR, or auditory, pass to the inner ears, and 

 are the nerves of hearing. 



THE NINTH PAIR, or glosso-pharyngeal, are distributed to the 

 mucous membrane of the pharynx and neighboring parts. 



THE TENTH PAIR, or pneumo-gastric, are the most widely 

 distributed of all the cranial nerves. They send branches to 

 the windpipe, lungs, gullet, stomach, heart, etc. 



