THE CRANIAL NERVES. 251 



membrane of -the nose and the adjacent sinuses, and finally supplies 

 the skin upon the crown of the head, the forehead, and the root and 

 point of the nose, Fig. 62. The second division, or superior maxillary, 

 supplies branches to the lining membrane of the nose, and Eustachian 

 tube, to the sinus in the upper jawbone, to the palate, to the upper 

 teeth and gums, and to the skin upon the side of the nose, the cheek, 

 and upper lip. The third, or largest division, the inferior maxillary, 

 supplies branches to the muscles of mastication, an important branch 

 to the anterior two-thirds of the tongue, named the gustatory nerve, or 

 nerve of taste, common sensory branches to the lower teeth and gums, 

 the floor of the mouth, and the skin of the external ear, temple, lower 

 part of the cheek and face, lower lip, and chin; and, lastly, branches 

 to a few neighboring muscles, and to the parotid gland. All three of 

 the divisions of this large nerve, give off sensory branches ; but only 

 the third division supplies motor branches. The three divisions of 

 the fifth nerve, are connected by some or other of their smaller 

 branches, with certain ganglia of the sympathetic nerve, and also with 

 the facial nerve. 



The sixth pair, or abducent nerves, abducentes oculorum, 6, arise 

 from between the pons and the medulla oblongata, receiving fibres from 

 both these parts. They supply a single muscle of the eyeball, viz., 

 the external rectus, which abducts the eye ; hence the special name of 

 these nerves. 



The seventh pair of cranial nerves, 7, consist, on each side, of two 

 portions, one soft, destitute of a firm neurilemma, named the portio 

 mollis, the other harder and round, named the portio dura; these are 

 distinctly different nerves. The portio mollis is the auditory nerve, 

 or nerve of hearing ; it arises at the back of the medulla oblongata, 

 from the floor of the fourth ventricle, and coursing forward, imme- 

 diately behind the pons, passes from the cranial cavity into an opening 

 in the petrous portion of the temporal bone, named the internal audi- 

 tory meatus or canal, at the bottom of which it pierces the bone by 

 minute openings, and is then distributed to the complicated chambers 

 of the internal ear. The portio dura arises also from the medulla ob- 

 longata, passes, with the portio mollis, into the internal auditory 

 meatus, and there communicates with it; but it then leaves that nerve 

 and escapes by a special opening, the stylo-mastoid foramen, through 

 the base of the skull, and emerges close to the inner side of the mas- 

 toid process. As it passes through the temporal bone, it presents a 

 gangliform swelling, which is connected with two neighboring sympa- 

 thetic cranial ganglia. It next descends outwards, behind the border 

 of the lower jaw, running through and supplying the parotid gland, 

 and then dividing into numerous branches (see Fig. 62), like the foot 

 of a bird, hence named pes anserinus or goose's foot, ramifies over the 

 face, and supplies all the facial muscles. It also supplies, partly, the 

 muscles of the outer ear, and likewise one little muscle of the tym- 

 panum or middle ear, and gives off a remarkable branch, named the 

 chorda tympani, which descends to the submaxillary salivary gland, 

 and joins the gustatory nerve. 



The eighth pair of nerves, 8, placed along the side of the medulla 



