108 



ZOOLOGY. 



from the skull behind the bulla, by the stylo-mastoid foramen. 

 It then runs forwards close under the skin of the cheek as 

 the facial nerve, and is distributed to the muscles of the 

 face. Besides this main trunk, two other small branches 

 must be noted a palatine branch, given off before the 



Fig. 58. DISTRIBUTION OF CHIEF CRANIAL NERVES OF BABBIT. 



tympanic chamber is reached, and a chorda tympani, given 

 off in that chamber and distributed to the salivary glands. 



14. Auditory Nerve. Nerve vm., unlike the two in 

 front and the two behind it, is purely sensory, yet it has no 

 ganglion. Its fibres belong to Si-polar cells within the bulb 

 itself. It enters the periotic bone, but never emerges from 

 it to the exterior of the skull, as it is exclusively distributed 

 to the internal ear, or essential organ of hearing, which is 

 completely enclosed in the periotic. 



15. Glossopharyngeal Nerve. Nerve ix. emerges by 

 the foramen lacerum posterius, curves round between 

 the larynx and the posterior cornu of the hyoid, and is 

 distributed to the sides of the throat and the posterior half 

 of the tongue. It is mainly sensory (nerve of taste), but in 

 part motor. 



16. Vagus Nerve. The tenth nerve has such a re- 

 markable distribution for a cranial nerve, extending as it 



