410 ANATOMY IN A NUTSHELL. 



LESSON CXV. 



The ninth cranial nerve called the glosso-pharyngeal passes to the tongue 

 and the pharynx. It supplies the raucous membrane of the pharynx, tonsil, 

 and fauces with ordinary sensation, and the tongue it supplies with a nerve of 

 taste. This nerve is a compound nerve. Its superficial origin is in the 

 groove between the olivary and restiform bodies. (Plate CLXXXVII). Its 

 DEEP ORIGIN is from the lower part of the floor of the fourth ventricle from three 

 main points. (1) from a nucleus of gray matter beneath the inferior fovea, (2) 

 from the funiculus solitarius, (3) from the nucleus ambiguus. The nucleus 

 ambiguus gives motor branches to the glosso-pharyngeal and the tenth nerves 

 and to the bulbar part of the spinal accessory nerve. The sensory fibers of the 

 ninth nerve are in the jugular and petrosal ganglia. Van Gehuchten says that 

 the fasciculus solitarius is the only sensory nucleus of this nerve. The ninth 

 nerve passes from its superficial origin outward to leave the skull through the 

 centra] part of the jugular foramen. It has a sheath of dura mater of its own 

 and is situated external to and in front of the pneumogastric and spinal acces- 

 sory nerves. It descends in front of the internal carotid artery and beneath 

 the styloid process and muscles attached to it to the lower border of the Stylo? 

 pharyngeus muscle. The nerve now passes inward, lying upon the Stylo- 

 pharyngeus and the Middle constrictor of the pharynx. It finally passes be- 

 neath the Hyo-glossus muscle to its destination. This nerve has two ganglia 

 upon it . The jugular ganglion or superior one is in the upper part of the groove 

 in which the nerve is placed while passing through the jugular formen. It is 

 quite smal] and may be regarded as a segmentation of the lower ganglion. The 

 petrous ganglion is the inferior one and is situated in the lower border of the 

 petrous portion of the temporal bone. It is much larger than the superior one. 

 Fibers arise from it to connect this nerve with the tenth and the sympathetic. 

 It sends two filaments to the pneumogastric, one of which passes to the auricu- 

 lar branch of the pneumogastric, and the other to the ganglion of the root of 

 the tenth. The branch which passes to the sympathetic passes to the superior 

 cervical ganglion, and the branch which passes to the facial nerve arises from 

 the nerve below the petrous ganglion and joins the facial just after it leaves the 

 stylo-mastoid foramen. (Plate CCXXII). 



It- branches of distribution are, (1) tympanic branch, called Jacobson's 

 nerve, comes from the petrous ganglion and passes in a small canal in the lower 

 surface of the petrous portion of the temporal bone. The lower opening of this 

 canal is on a ridge between the carotid canal and the jugular fossa. This nerve 

 now passes to the tympanum and forms the typmanic plexus. This plexus 

 gives off (a I a greater pari of the small superficial petrosal, (b) a branch to the 

 large superficial petrosal, (c) branches to the tympanic cavity, (d) branches to 

 the carotid plexus,(e) to the Eustachian tube, (f) to fenestra ovalis, (g) to fen- 

 estra rotunda. 



(2) Pharyngeal branches which are three or four in number unite with 

 the pharyngeal branches of the pneumogastric and sympathetic nerves to form 



