. Animal physiology. Physiology, Comparative; Physiology, Comparative. 390 TYMPANIC APPARATUS. colds. Within the cavity of the tympanum, there is a very curious apparatus of small bones and muscles, which serves to establish a connection between the membrane of the drum, and the small membrane covering the entrance to the internal ear. These bones are four in number; and are termed the malleus or hammer («, Fig. 191) ; the incus, or anvil (b) ; the os orbiculare, a b a minute globular bone (c); and the stapes, or J-. | stirrup-bone (d). These bones are connected to- «=£?r Jf^s gether in the ma
. Animal physiology. Physiology, Comparative; Physiology, Comparative. 390 TYMPANIC APPARATUS. colds. Within the cavity of the tympanum, there is a very curious apparatus of small bones and muscles, which serves to establish a connection between the membrane of the drum, and the small membrane covering the entrance to the internal ear. These bones are four in number; and are termed the malleus or hammer («, Fig. 191) ; the incus, or anvil (b) ; the os orbiculare, a b a minute globular bone (c); and the stapes, or J-. | stirrup-bone (d). These bones are connected to- «=£?r Jf^s gether in the manner represented in Fig. 192; if \) where a a represents the wall of the tympanic JT"'c cavity; 5, the membrana tympani; c, one of the «r* long processes of the malleus, which is attached to the membrane; d, the head of the malleus, d which articulates with the incus; e, the other Fig. J91. , , Bones of the ear. long process of the malleus, which is acted on by the minute muscle,/; g, the incus, of which one leg is in contact with the wall of the cavity, g a whilst the other is connected ; with the orbicular bone, h; i, the stapes, of which the a upper end is connected with the orbicular bone, whilst the low- h er (which is of an oval form) is attached to the membrane that covers the entrance to i the internal ear; and k is \ \ \ a small muscle which acts ' \ \ upon this bone, in such a a b c b manner as to regulate its Ro. of the tympanum, with ° the Bones in their Places. movements. 517. The use of this apparatus is evidently to receive the sonorous vibrations from the air, and to transmit them to the membrane forming the entrance to the internal or essential part of the organ of hearing; in such a manner, that the sonorous vibrations excited in the latter may be much more powerful than they would be if the air acted immediately upon it. The usual state of the membrane of the tympanum appears to be rather lax. Please note that these images are extracted
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Keywords: ., bookauthorcarpenterwilliambenja, bookcentury1800, bookdecade1840
