616 



THE CRANIAL NERVES. 



portion of the temporal bone, and presents, successively, two ganglionic 

 enlargements, the jugular ganglion, and the petrous ganglion. 



After leaving the skull, the glosso-pharyngeal nerve appears between the 

 internal carotid artery and the jugular vein, and is directed downwards over 

 the carotid artery and beneath the styloid process and the muscles con- 

 nected with it, to the lower border of the stylo-pharyngeus muscle. Here, 

 changing its direction, the nerve curves inwards to the tongue, on the 

 stylo-pharyngeus and the middle constrictor muscle of the pharynx, above 

 the upper laryngeal nerve ; and, passing beneath the hyo-glossus muscle, 

 ends in branches for the pharynx, the tonsil, and the tongue. 



Fig. 414. Fig. 414. DIAGRAMMATIC! SKETCH 



PROM BEHIND OF THE ROOTS OF THE 

 NERVES OF THE EIGHTH PAIR, WITH 

 THEIR GANGLIA AND COMMUNICA- 

 TIONS (from Beudz). 



A, part of the cerebellum above the 

 fourth ventricle ; B, medulla oMon- 

 gata; C, posterior columns of the spinal 

 cord ; 1, root of the glosso-pharyngeal 

 nerve ; 2, roots of the pneumo-gastric ; 



3, 3, 3, roots of the spinal accessory, 

 the uppermost number indicating the 

 filaments intermediate between the 

 spinal accessory and pneumo-gastric ; 



4, jugular ganglion of the glosso-pha- 

 ryngeal ; 5, petrous ganglion ; 6, 

 tympanic branch ; 7, ganglion of the 

 root of the pneurao-gastric ; 8, auri- 

 cular branch ; 9, long ganglion on the 

 trunk of the pneumo-gastric; 10, 

 branch from the upper ganglion to the 

 petrous ganglion of the glosso-pharyn- 

 geal ; 11, inner portion of the spinal 

 accessory ; 12, outer portion ; 13, 

 pharyngeal branch of the pneumo- 

 gastric ; 14, superior laryngeal 



branch ; 15, twigs connected with the sympathetic ; 16, fasciculus of the spinal accessory 

 prolonged with the pneumo-gastric. 



The jugular ganglion, the smaller of the two ganglia of the glosso- 

 pharyngeal nerve, is situated at the upper part of the osseous groove in 

 which the nerve is laid during its passage through the jugular foramen. 

 Its length is from half a line to a line, and the breadth from half to three 

 fourths of a line. It is placed on the outer side of the trunk of the nerve, 

 and involves only a part of the fibres, a small fasciculus passing over the 

 ganglion, and joining the nerve below it. 



The petrous ganglion is contained in a hollow in the lower border of the 

 petrous part of the temporal bone (receptaculuin ganglioli petrosi), and 

 measures about three lines in length. This ganglion includes all the fila- 

 ments of the nerve, and resembles the gangliform enlargement of the facial 

 nerve. From, it arise the small branches by which the glosso-pharyngeal is 

 connected with other nerves at the base of the skull : these are the tympanic 

 nerve, and the branches which join the pneumo-gastric and sympathetic. 



CONNECTING BEANCHES, AND TYMPANIC BRANCH. 



From the petrous ganglion spring three small connecting filaments. One passes 

 to the auricular branch of the pneumo-gastric, one to the upper ganglion of the sym- 



