TYMPANIC CAVITY 



5 11 



tympanum and the jugular fossa. It separates the tympanum 

 from the bulb of the internal jugular vein, and an exten- 

 sion of an inflammatory condition of the middle ear, through 

 the bone to the vein, may lead to thrombosis (clotting). 



Ampulla of lateral semi-circular canal 

 Ampulla of superior semi-circular canal 



Utricle 

 Saccule 



Facial nerve 



Aditus to tympanic antrum 



Facial nerve 



Acoustic nerve 

 (upper division) 

 Acoustic nerve 

 (lower division) 



Cochlea 



Auditory tube 



External acoustic 

 mea.tus 



Head of malleus 



\ Remains of anterior 

 \ process of malleus' 



Handle of malleus 



cus (long crus of) 



! I 



Air cell I 



I 



Membrana tympani 



Styloid process Facial nerve 

 FIG. 209. The Tympanic Cavity and adjacent parts (semi-diagrammatic). 



The posterior or mastoid wall presents, in its upper part, 

 the opening or aditus which leads from the recessus epi- 

 tympanicus into the tympanic antrum, and below that, close 

 to the medial wall, is a small hollow conical projection termed 

 the pyramid (Fig. 213). The pyramid is perforated on its 

 summit, and the aperture leads into a canal which curves 

 backwards and then downwards until it opens into the lower 



