OF THE SENSE OF HEABING. 109 



ear, the middle ear, and the internal ear. The external ear is 

 composed of the pavilon or figured part of the ear, and the 

 auditory canal. 



The figured part of the ear is composed of a fibre-cartila- 

 ginous lamina, adhering to the 'edge of the auditory cana^and 

 covered with a very fine and thin skin, dry and tense, and is 

 so arranged as to form an acoustic tube. The lobe of the ear 

 is not supported by any cartilage. The auditory tube is 

 partly cartilaginous and partly osseous ; the integuments 

 pass into it, and terminate by a cul-de-sac over the drum of 

 the ear. It is in this tube or canal that we find the small 

 sebaceous follicles which secrete the cerumen that is, the 

 wax of the ear. 



d 



C 



Fig. 62. Tympanum and Ossicula Auditus.* 



The middle ear is composed of the tympanum, of the cavit}' 

 of the tympanum, and parts connected with it. 



The cavity of the tympanum is a cavity of an irregular form, 

 hollowed out in the substance of the rocky part of the tem- 

 poral bone, and separated from the auditory canal by the mem- 

 brane of the tympanum. Opposite to this membrane are two 

 openings, called the fenestra ovalis and rotunda. In the 

 back wall of the cavity is an opening leading to the mastoid 



* Represents the cavity of the tympanum, the ossicula auditus, and their 

 muscles, magnified. a a, cavity of the tympanum; b, membranatympani, or 

 rather the osseous circle to which it is attached ; c, handle of the malleus, 

 resting on the middle of the membrana tympani ; d, head of the malleus 

 articulating with the incus ; e, long handle of the malleus, passing into the 

 glenoidal fissure ; the anterior muscle of the malleus is attached to it ; f, in- 

 ternal muscle of the malleus; g, anvil; h, lenticular bone; t, stapes; 

 k, musculus stapedius. 



