xvii THK NKkVOL'S SVM I M 191 



divides into tlirce main divisions. It arises by two 

 roots, a motor root and a sensory root, and so resembles 

 a ^pinal nerve, and the sensory root, like that of a spinal 

 nerve, possesses a ganglion. It is the motor nerve for 

 the muscles of mastication and the sensor)- nerve for 

 the mouth and tongue. 

 The sixth pair. Motor nerve, going to one of the musrles 



(the external rectus muscle) which moves the eyeball. 

 The seventh pair. Motor nerve, going to the muscles of the 

 face, mouth, and lips, and therefore called the facial. 

 These muscles give rise to expression by drawing upon 

 and moving the skin of the face. 



The eighth pair. The auditory nerve, or nerve of hearing. 

 The ninth pair. The glosso-pharyngeal nerve, like the 

 fifth, partly sensory and partly motor. The main 

 sensory part goes to the tongue, and is the chief nerve 

 of taste. The motor part supplies the muscles of the 

 pharynx. 



The tenth pair. The vagus or pncumogastric nerve. A 

 large nerve which passes from the head down the neck 

 to the thorax and abdomen. It is partly motor and 

 partly sensory. It gives branches to the larynx, the 

 lungs, the heart, the uusophagus, the stomach, intestine, 

 and the liver. 



The eleventh pair. The spinal accessory nerve. Motor 

 nerve arising by many roots from the upper part of 

 the spinal cord and then running upwards, gaining 

 more fibres from the bulb before it passes out, as it 

 does, with the vagus nerve. It goes to certain muscles 

 of the neck. 



The twelfth pair. The hypoglossal nerve. Motor nerve 

 for the musrles of thr tongue. 



Of the cranial nerves the last six arise from the spinal 

 bulb, and all of the other six except the first two arise from 

 the purls of the brain just in front of the bulb. 



Tin- first two cranial nerves are not nerves like the others, 

 but in reality processes of the brain. 



The Functions of the Spinal Bulb. Thr spinal bulb, 

 besides giving rise to so many of the cranial nerves, is in 



