55 2 



THE AUDITORY APPARATUS 



round which the tendon of the muscle turns abruptly, in a 

 lateral direction, towards the malleus. 



The medial wall, which intervenes between the tympanum 

 and the labyrinth, presents certain important points for study. 

 The greater part of this wall bulges laterally, into the cavity, 

 in the form of a very evident elevation termed the promontory. 

 Above the posterior part of the promontory there is an oval 

 foramen, the fenesfra vestibuli. Its long axis is directed 

 antero-posteriorly, and it opens into the vestibular part of 



Recessus 

 epitympanicus 



Body of inc 



Short cms 



of incus 

 Ligament 



of incus 



!horda tym- 

 pani nerve 

 Pyramid 



Foot of stapes 



; Superior ligament of malleus 



Head of malleus 



Anterior ligament 

 of malleus 



Handle of malleus 



FIG. 236. Left Membrana Tympani and Chain of Tympanic Ossicles 

 seen from the inner aspect. (Howden.) 



the labyrinth in the macerated bone, but is closed in the 

 recent state by the footpiece of the stapes, the most medial 

 of the auditory ossicles. The pyramid, on the posterior wall, 

 is immediately posterior to the fenestra vestibuli. Above the 

 fenestra vestibuli, in the angle formed by the meeting of 

 the roof and medial wall of the tympanum, and there- 

 fore in the recessus epitympanicus, is an antero- posterior 

 ridge. This is produced by the canalis facialis bulging into 

 the tympanum. The wall of the canal is very thin, and 

 allows the white colour of the facial nerve, which is contained 

 within the canal, to be readily seen. Below the posterior 

 end of the promontory is the fenestra cochlea, an aperture 



