390 



HITCHCOCK'S ANATOMY 



are in fact rudimentary muscles, 5 in number. In some men 

 they have been so fully developed that the ears could be 

 moved by their action, while among quadrupeds there are but 

 few that do not possess this power. The Pinna somewhat 

 resembles a funnel, forming at its base an irregular tube called 

 the Auditory Canal, about half an inch in diameter and an 

 inch in length, which terminates with the Tympanum. A 

 few stiff hairs are found upon the sides of this canal, and in 

 the lining membrane some glands, which secrete the wax of 

 the ear. 



716. The Tympanum — Membrana Tympani. — Little 

 Cones of the Ear. — The Tympanum is an irregular cav- 

 ity located in the petrous portion of the Temporal bone, 

 measuring rather more than one half inch in its longest 

 diameter. At the point where the Auditory Canal joins 



the Tympanum, the 

 ElG * 359 * Membrana Tympani is 



found, which is simply 

 an impervious mem- 

 brane stretched between 

 the two cavities, dip- 

 ping inwards at an an- 

 gle of forty-five degrees. 

 To this membrane are 

 attached three muscles 

 for the purpose of ren- 

 dering this membrane 

 lax or tense, as may be 



View of the Cavity of the Tympanum, the Ossieula Auditus, and their Muscles, magni- 

 fied, a, a, Cavity of the Tympanum, b, Membrana Tympani, 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, Internal Muscle of the Malleus, ff, Anvil, h, Lenticular 

 Bone, i, Stapes. Muscular Stapedius. 



Can the ear ever be moved ? How many rudimentary muscles are placed on it? 716. 

 What is the tympanum ? Describe the membrana tympani. 



