AUDITORY TUBE 559 



part of the medial surface of the manubrium of the malleus. 

 The tensor tympani receives its nerve of supply from the otic 

 ganglion. 



Chorda Tympani Nerve. The chorda tympani, which 

 traverses the tympanic cavity in close relation to the upper 

 part of the membrana tympani, is described on p. 546. 



Tympanic Plexus. This has been described previously 

 on p. 312. 



Tuba Auditiva (O.T. Eustachian). The auditory tube is 

 the passage which places the tympanic cavity in communica- 

 tion with the pharynx. Through it air reaches the tympanic 



Tympanic antrum 



Temporal line 

 rLxternal meatus \ j 



Mastoid notch (O.T. 

 Digastric fossa). 



Air-cells in mastoid part 

 of temporal bone 



FIG. 244. Dissection of the Tympanic Antrum and the mastoid part of 

 the temporal bone from the outer side. 



cavity and antrum and the mastoid cells. It consists of an 

 osseous and a cartilaginous portion. The osseous portion is 

 about half an inch in length. It is widest at its entrance 

 into the tympanum, and narrowest at its other end. The 

 cartilaginous portion is about an inch in length, and has been 

 already described on p. 383. 



Dissection: Second Method. On the opposite side the bony part of 

 the external meatus, the tympanic antrum, and the tympanic cavity should 

 be approached from the postero-lateral aspect. The dissection of the bone 

 should be carried out after the manner adopted by the surgeon when operat- 

 ing for the cure of extensive mastoid and middle ear disease, but, to 

 facilitate the dissection, and to gain better access to the bone, the auricle 

 may be removed by cutting through the cartilaginous part of the external 

 meatus. 



After the auricle has been cut away clear all the soft parts, including 



