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In frogs and toads, the tympanum is a large external oval shape membrane made up of nonglandular skin. [2] It is located just behind the eye. It does not process sound waves; it simply transmits them to the inner parts of the amphibian's ear, which is protected from the entry of water and other foreign objects.
In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit changes in pressure of sound from the air to the ossicles inside the middle ear, and thence to the oval window in the ...
The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear.The adult human ear canal extends from the auricle to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.
Auditory ossicles from a deep dissection of the tympanic cavity. Sound waves travel through the ear canal and hit the tympanic membrane, or eardrum. This wave information travels across the air-filled middle ear cavity via a series of delicate bones: the malleus (hammer), incus (anvil) and stapes (stirrup).
Perilymph and endolymph have unique ionic compositions suited to their functions in regulating electrochemical impulses of hair cells necessary for hearing. The electric potential of endolymph is ~80-90 mV more positive than perilymph due to a higher concentration of potassium cations (K +) in endolymph and higher sodium (Na +) in perilymph. [4]
The round window is situated below (inferior to) and a little behind (posterior to) the oval window, from which it is separated by a rounded elevation, the promontory.. It is located at the bottom of a funnel-shaped depression (the round window niche) and, in the macerated bone, opens into the cochlea of the internal ear; in the fresh state it is closed by a membrane, the secondary tympanic ...
Georg von Békésy (1899–1972) employed the use of a microscope in order to examine the basilar membrane located within the inner-ear of cadavers. He found that movement of the basilar membrane resembles that of a traveling wave; the shape of which varies based on the frequency of the pitch.
The petrotympanic fissure opens just above and in front of the ring of bone into which the tympanic membrane is inserted; in this situation it is a mere slit about 2 mm. in length. It lodges the anterior process and anterior ligament of the malleus, and gives passage to the anterior tympanic branch of the internal maxillary artery. The iter ...