When the sound strikes the tympamc membrane, the membrane vibrates and the vibration of The membrane

y skin and middle ear side by mucous membrane. The middle ear cavity contains three small pieces of bone, called ssicles, viz (i) malleus (= hammer), (ii) incus (= anvil) and (in) stapes (= stirrup*) They are so named because of iheir hapes, the handle of the malleus is attached with the central part of the tympanic membrane, the central part of the-hembrane being called 'umbo'. The malleus In turn is attached by ligaments with incus and the incus with the stapes he foot plate of the stapes rests on the 'oval window' of the cochlea (figs.10B2.4.2(a) and 10B2.4.3) When the sound strikes the tympamc membrane, the membrane vibrates and the vibration of The membrane, is transmitted through ossicles till it reaches the foot of the stapes. The foot of the stapes thus develops a rock' "Anwl= block of iron on a blacksmith works his metal. Stirrup = (horse) rider's foot step consisting of a loop. These two bones, look like anvil nd stirrup respectively, ing movement and the axis of the movement is perpendicular to the long axis of the body of the erson. Middle ear muscles (MEM) In the middle ear cavily. two muscles, called (i) tensor tympam, and (ii) stapedtus, xist. Their functions are not fully clear. On the whole, the functions of the MEMs however, appear to be as follows (i) he tensor fympam, which is attached to the malleus, when contracts causes the tympanic membrane to become taut and hus its contraction causes reduction of the amplitude of vibration of the ear drum, which the, the ear drum) is thus rotected from injury when the pressure or the sound wave is too high.