CRANIAL NERVES. 517 



and ends in the face below the orbit. And the last, or the inferior 

 maxillary //< : /T<>. passe? through the foramen ovale to reach the 

 lower jaw, the lower part of the face, and the tongue. 



The small root of the fifth nerve, lying in the same tube of the Small root, 

 dura mater as the large one, passes beneath the ganglion without 

 communicating with it, and joins only one of the three trunks derived 

 from the ganglion: if the ganglion be raised, this root will be seen 

 to enter the inferior maxillary nerve. 



Those branches of the ganglion which are unconnected with the Difference in 

 small or motor root, viz., the ophthalmic and superior maxillary, f}]e roots* 

 are solely nerves of sensibility ; but the inferior maxillary, which 

 is compounded of both roots, is a nerve of sensibility and motion. 

 It will moreover be subsequently seen that the fibres of the motor 

 root are almost entirely confined to that part of the inferior maxillary 

 nerve which supplies the muscles of the lower jaw, and that the 

 larger branches of the nerve are wholly sensory in function. 



The ophthalmic m-rve is the onlv one of the three trunks which Ophthalmic 

 , . , ,. . , : r ,, ,. T , . nerve enters 



needs a more special notice in this stage ot the dissection. It is orbit ; 



continued through the sphenoidal fissure and the orbit to the fore- 

 head. In form it is a flat band, and is contained in the wall of 

 the cavernous sinus below the third and fourth nerves. Near the 

 orbit it divides into three branches, frontal, nasal, and lachrymal. 



In this situation it is joined by filaments of the cavernous plexus supplies 

 of the sympathetic, and gives a small recurrent filament (fig. 189, f) inJts course, 

 to the tentorium cerebelli. 



The SIXTH or ABDUCENT NERVE (fig. 189, 6 ) enters the orbit Sixth nerve 

 through the sphenoidal fissure, and supplies one of the orbital O us sinus ; 

 muscles. It pierces the dura mater behind the body of the 

 sphenoid bone in the wall of the inferior petrosal smus, and 

 crosses the space of the cavernous sinus, to gain the outer wall 

 with the other nerves. 



In the sinus the nerve is placed close against the outer side of joins sym- 

 the carotid artery ; and it is joined by one or two large branches P atbetic - 

 of the sympathetic nerve surrounding that \<- 



The SEVENTH or FACIAL and the EIGHTH or AUDITORY NERVES Seventh and 

 (fig. 189, ~) pass together into the internal auditory meatus, the nerves leave 

 facial being the smaller and higher of the two. At the bottom of skull to- 

 the meatus they separate ; the facial nerve courses through the 

 aqueduct of Fallopius to the face, and the auditory nerve is 

 distributed to the internal ear. 



The NINTH or GLOSSO-PHARYNGEAL, the TENTH, PNEUMO-GASTRIC Ninth, 

 or VAGUS, and the ELEVENTH or SPINAL ACCESSORY NERVES (tig. 189, 8 ) gf"^^" 1 

 pass through the middle compartment of the jugular foramen, nerves pass 

 The glosso-pharyngeal is external to the other two, and has a fJj^SjJ 1 

 distinct opening in the dura mater. The spinal accessory nerve foramen. 

 asi-eiids through the foramen magnum and, together with the 

 vagus, enters an aperture in the dura mater close to the occipital 

 bone. 



The TWELFTH or HYPOGLOSSAL NERVE (fig. 189, 9 ) is the motor Twelfth 

 nerve of the tongue, and consists of two small pieces, which pierce n 



