DISSECTION OF THE HEAD. 



to Meckel's 

 ganglion, 

 tympanic of 

 glosso-pha- 

 ryngeal, and 

 sympa- 

 thetic ; 



nerve to 

 stapedius ; 



chorda 

 tympani 

 to lingual. 



Auditory 

 nerve. 



Otic 



ganglion. 



Dissection 

 to find it, 



proceed. One is the large superficial petrosal nerve ( 2 ), passing to 

 the Vidian ; another is a filament* of communication with the 

 small superficial petrosal nerve of the tympanic plexus ( 3 ) ; and the 

 third is the external superficial petrosal nerve* ( 4 ), which unites the 

 ganglion with the sympathetic on the middle meningeal artery. 



* The branch of the stapedius muscle arises at the back of the 

 tympanum, and is directed forwards to its muscle. 



Chorda tympani. This long but slender branch of the facial 

 nerve crosses the tympanum, and ends in the tongue. Arising about 



a quarter of an inch 

 from the stylo-mastoid 

 foramen, it enters 

 the tympanum below 

 the pyramid. In the 

 cavity (fig. 240, 5 ) the 

 nerve is directed for- 

 wards across the han- 

 dle of the malleus and 

 the membrana tympani 

 to an aperture on the 

 inner side of the Gla- 

 serian fissure, through 

 which it leaves the 

 tympanum. 



Outside the skull 



FIG. 241. THE OTIC GANGLION PROM THE the chorda tympani 

 INNER SIDE. 



a' 



a. Tensor tympani muscle. 



b. Internal pterygoid muscle. 



c. External carotid artery with 



the sympathetic on it. 



1. Otic ganglion. 



2. Small superficial petrosal nerve. 



3. Nerve to tensor tympani. 



4. Chorda tympani joining lingual. 



5. Nerve to internal pterygoid. 



6. Nerve to tensor palati. 



7. Auriculo- temporal nerve. 



joins the lingual nerve, 

 and continues along it 

 to the submaxillary 

 ganglion and the tongue 

 (p. 625). 



The AU DITORY 

 NERVE will be learnt 

 with the ear. Entering 

 the internal auditory 

 meatus with the facial 



nerve, it divides into 



an upper smaller, and a lower larger part, which are distributed to 

 the membranous labyrinth. 



OTIC GANGLION. At this stage of the dissection there is little to 

 be seen of the ganglion, but the student should keep in mind that 

 it is one of the things to be examined in a fresh part. Its situation 

 is on the inner aspect of the inferior maxillary nerve, immediately 

 below the foramen ovale, and it adheres closely to the trunk of the 

 nerve. 



Dissection (fig. 241). Putting the part in the same position as for 

 the examination of Meckel's ganglion, the dissector should define 

 the Eustachian tube and the muscles of the palate, and then take 

 away the levator palati and the cartilaginous portion of the tube, 



