THE RABBIT. 107 



11. Posterior Cranial Nerves. The next series of 

 nerves (v., vn., ix., and x.), have much more resemblance to 

 spinal nerves. They are mixed nerves, i.e. contain both 

 sensory and motor fibres, though some of their branches 

 may contain only one of the two. Their sensory fibres 

 come from unipolar cells in a ganglion at the side of the 

 hind-brain (bulb), and they have branches running to other 

 ganglia which resemble those of the sympathetic. But the 

 dorsal and ventral roots tend to run together, and are never 

 as distinct as those of spinal nerves. These nerves, along 

 with vni. (auditory), arise in order from the sides of the 

 bulb. 



12. Trigeminal Nerve. Nerve v. has a large ganglion 

 (the gasseriari) from which its sensory fibres come. It 

 divides into three branches (hence its name). The first 

 two are sensory : they emerge from the skull by foramina 

 in the alisphenoid, called the foramen lacerum anterius and 

 foramen rotund urn respectively.* The first (v.i), called 

 ophthalmic, runs on the dorsal side of the eye, and is dis- 

 tributed to the skin of the upper part of the face. The 

 second, or maxillary (v. 2 ), runs ventral to the eye, through 

 the maxilla, and is distributed to the skin of the snout, 

 especially to the tactile " whiskers," or vibrissae. The third 

 branch, or mandibular (v. 3 ), runs through the foramen 

 ovale * then turns down towards the lower jaw, sends a 

 branch to the tongue (its only sensory, gustatory branch), 

 continues on the inner side of the mandible, eventually 

 passes through a foramen in the mandible and is distributed 

 to the muscles of the lower jaw, and to the teeth. 



13. Facial Nerve. Nerve vn., though included in the 

 mixed nerves, is practically all motor in the rabbit. Its 

 relation to the ear should be noted. It is strictly anterior 

 to the essential parts of the ear (internal ear), but runs 

 through the periotic bone and then bends back so as to run 

 posterior to the tympanic chamber (chap, x., 6), and emerges 



* These statements are strictly true of the dog, but in the rabbit 

 these three foramina are united into one. These and the foramina 

 subsequently named are all shown on figs. 45 and 46. 



