GUIDE TO THE HEAD AND NECK 15^5 



relation with that branch of the parent trunk, the otic (Arnold's) ganglion 

 falls to receive consideration. The relation of the ganglion to the smcill 

 superficial petrosal and auriculo-temporal nerves is to be borne carefully in 

 mind. The ganglion lies immediately below the foramen ovale, between the 

 inferior maxUlary nerve and the cartilaginous part of the Eustachian tube, 

 and the middle meningeal artery is situated behind it. The source of the 

 motor root of the ganglion from the nerve to the internal pter\-goid muscle 

 will be readily understood, but the dissector must not overlook the small 

 superficial petrosal nerve, which conducts to the ganglion fibres of the glosso- 

 pharyngeal and facial nerves. The cartilaginous part of the Eustachian 

 tube in this vicinity may be made apparent by removing, at the discretion of 

 the dissector, the portion of the great wing of the sphenoid bone which lies 

 internal to the foramen ovale. This dissection will allow of the branches of 

 the otic ganglion being displayed. One branch will be found to pass upwards 

 and backwards to the tensor tympani muscle ; a second, downwards and for- 

 wards to the tensor palati muscle ; branches to the auriculo-temporal nerve ; 

 and a branch to the chorda tympani nerve. These, however, are extremely 

 difficult of dissection ; nevertheless, an effort made will not be without its 

 reward. 



Deep Dissection of the Neek. — A very complicated dissection has now to 

 be overtaken. It is impossible to lay down hard-and-fast instructions for 

 the guidance of the dissector. He is advised to make himself master of what 

 has been carefully stated in the text. The structures referred to are (i) the 

 glosso-pharyngeal, (2) the pneumogastric, (3) the spinal accessory, (4) the 

 hypoglossal, (5) the superior cervical ganglion of the sympathetic, nerves, 

 and (6) the cervical part of the internal carotid artery, along with the upper 

 part of the internal jugular vein. After he has done his best to study these 

 very important structures the dissector is to revise the styloid muscles and 

 ligaments, and thereafter the styloid process of the temporal bone is to be 

 nipped through, and turned downwards and forwards. This procedure may 

 be advisable in the course of the immediately preceding dissection. Without 

 doubt the dissector will find himself in very deep water here. He should, 

 however, try his best. When he gets clear of the difficulties in the upper 

 part of the neck near the base of the skull, his course is fairly clear. 



The spinal accessor}' nerve is to be completely mjistered, and its bulbar 

 part, of considerable importance, is to be shown applying itself to the ganglion 

 of the trunk of the pneumogastric. The distribution of the spinal part of the 

 nerve must by this time be familiar to the dissector. 



The glosso-pharyngeal nerve is to be followed in accordance with the 

 description which has been given of it in the text. 



The ganglion of the trunk of the pneumogastric nerve admits of easy 

 dissection, but must receive careful study. Its pharyngeal and superior 

 laryngeal branches demand most careful attention, and the relation to it of 

 the bulbar part of the spinal accessory nerve is to be specially noted. The 

 pharyngeal branch, conducting fibres of the bulbar part of the spinal accessory, 

 will be found to contribute largely to the pharyngeal plexus, the other con- 

 tributory nerves being derived from the glosso-pharyngeal and the superior 

 cervical ganglion of the sympathetic. The superior laryngeal nerve has 

 already been followed out in its internal and external laryngccil branches, but 

 the dissector should note that it must contain some of the fibres of the bulbar 

 part of the spinal accessory nerve. The parent trunk of the pneumogastric 

 is now to be carefully studied in its course down the neck. The dissector 

 will be already quite familiar with it. A superior aJid an inferior cervical 

 cardiac branch are to be kept in view. 



As regards (i) the auricular branch of the pneamogastric, colloquially 

 referred to as Arnold's nerve, and (2) the tjinpanic branch of the glosso- 

 pharyngeal nerve (Jacobson's nerve), the dissector is recommended to accept 

 these as described in the text, unless he desires to pursue a dissection of the 

 most intiicate nature possible. 



The sympathetic cord is now to be dissected. The superior cervical ganglion, 

 of great length and elliptical shape, can easily be shown, and an efifart 



