MCAT Behavioral Sciences Question 183: Answer and Explanation
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Question: 183
3. What structure in the middle ear generates vibrations that match the sound waves striking it?
- A. Basilar membrane
- B. Tympanic membrane
- C. Cochlea
- D. Malleus
Correct Answer: B
Explanation:
The tympanic membrane (also known as the eardrum), located in the middle ear, generates vibrations that match the sounds waves striking it (choice B is correct). Vibrations generated in the tympanic membrane pass through three small bones—the malleus (the hammer), the incus (anvil), and the stapes (stirrup); these bones magnify the incoming vibrations by focusing them onto a structure known as the oval window (choice D is wrong). Once the vibrations pass through the oval window, they enter the cochlea, a fluid-filled spiral structure in the inner ear (choice C is wrong). The base of the cochlea is lined with a long, fluid-filled duct known as the basilar membrane (choice A is wrong). Sound waves passing along the basilar membrane cause it to move up and down, stimulating hair cells in the organ of Corti. These hair cells, in turn, connect with the acoustic, or auditory nerve.