Question 1

What are the three ear ossicles in order?

Accepted Answer

The ear ossicles, in order from the tympanic membrane to the inner ear, are the malleus, incus, and stapes. The malleus attaches to the tympanic membrane, and the stapes sits on the oval window of the cochlea. Together they act as an impedance-matching lever that amplifies pressure roughly 20 times.

Question 2

What is the organ of Corti?

Accepted Answer

The organ of Corti is the sense organ of hearing, located on the basilar membrane inside the cochlear duct (scala media). It contains hair cells whose stereocilia project towards the overlying tectorial membrane. Bending of these stereocilia generates receptor potentials that travel via the auditory nerve.

Question 3

What is the difference between perilymph and endolymph?

Accepted Answer

Perilymph fills the scala vestibuli and scala tympani of the cochlea. Endolymph fills the scala media (cochlear duct) and is unusual for being rich in potassium ions. Confusing the two fluids is a common NEET trap.

Question 4

How does the cochlea distinguish high and low pitch?

Accepted Answer

Through tonotopy: the basilar membrane is narrow and stiff at its base, so high-frequency sounds peak there, while it is wide and floppy at the apex, where low-frequency sounds peak. The brain reads the place of maximum vibration as pitch — pitch is literally a location on the membrane.

Question 5

What is the function of the round window?

Accepted Answer

Cochlear fluid is incompressible, so when the stapes pushes fluid in through the oval window, the round window bulges outward to relieve that pressure. Without this release, the fluid could not vibrate and no travelling wave would form on the basilar membrane.

The Cochlea: Pitch Is a Place — Hearing Lab

Practice

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