806 



DISSECTION OF THE EAK. 



Fallopius; ^ one ( c /*) which marks the situation of the aqueduct of Fallopius, 

 and contains the facial nerve. Lastly, in front of this ridge, and 

 close to the roof of the fore part of the cavity, is the ending of the 



and canal of canal for the tensor tympani muscle (ctt). The canal is separated from 

 the Eustachian tube (et] below it by a thin plate of bone named 

 the cochleariform process (cp) ; this becomes expanded on reaching the 



or* 



tensor 

 tympani. 



FIG. 



296. INNER WALL OF THE LEFT TYMPANUM : 

 NATURAL SIZE. 



THREE TIMES THE 



pr. Promontory. 



fo. Fenestra ovalis. 



fr. Fenestra rotunda. 



py. Pyramid. 



cf. Canal of the facial nerve (aque- 

 duct of Fallopius), cut obliquely. 



cf*. Ridge formed by the canal of 

 the facial nerve. 



am. Antrum mastoideum. 



tt. Tegmen tympani. 



ctt. Canal of the tensor tympani. 



cp. Cochleariform process. 



et. Eustachian tube. 



cc. Carotid canal. 



cty. Canal of tympanic nerve. 



jf. Jugular fossa. 



tympanic cavity, and being bent upwards, prolongs the canal 



beyond the end of the Eustachian tube. In most cases the outer 



wall of the tympanic portion of the canal is partly formed by 



fibrous tissue. The aperture by which the tendon of the muscle 



escapes is placed a little above and in front of the fenestra ovalis. 



On outer The outer boundary of the cavity is formed by the membrana 



memb?ana tvm P an i ( n g- 2 ^5, c), and the surrounding bone. Above and in 



tympani and front of the membrane is the upper opening of the Glaserian fissure, 



fissure!* 11 which is occupied in the fresh condition by the long process of one 



of the small bones (malleus) and some fibres of its anterior ligament, 



