Question

The basilar membrane of the cochlea
(a) Is unaffected by movement of fluid in scala vestibuli
(b) Covers the oval window and round window
(c) Vibrate in a pattern determined by the form of the traveling wave in the fluids of the cochlea
(d) Vibrate when the body is subjected to linear acceleration

Answer 1

Hint: Each ear consists of three portions- external ear, middle ear, and inner ear. The cochlea is present in the inner ear. The inner ear is connected to the middle ear by small openings. The cochlea is divided into three compartments filled with a dense liquid.

Complete answer:
The inner ear is represented by semicircular canals, the vestibules, and the cochlea. Internally it is divided into three areas filled with fluid- scala vestibuli, scala media, and scala tympani. The scala vestibuli is connected to the middle ear by a small oval window known as fenestra ovalis. Likewise, the scala tympani ends at a small window called fenestra rotunda.
The basilar membrane separates scala media and scala tympani. The sensory hair cells of the organ of Corti on the basilar membrane vibrates in a pattern determined by the patterns of waves generated in the fluids of the cochlea. They are extremely sensitive and vibrate in response to any soundwaves irrespective of the movement of the body.
- The inner ear is also known as the labyrinth due to a complicated series of channels.
- These channels are separated into three compartments-scala vestibuli, scala media, and scala tympani.
- Scala vestibuli and scala tympani are separated except at a small opening called helicotrema near the apex of the cochlea. They are filled with a fluid known as perilymph.
- Scala media is filled with endolymph and is separated from the scala vestibuli by a vestibular membrane and scala tympani by a basilar membrane, on which the organ of Corti is present.
- The vibrations in the ear enter the inner ear by the oval window which leads to pressure waves in the perilymph of the cochlea.
- The movement of perilymph fluid in scala vestibuli affects the basilar membrane of the cochlea.
So, the correct answer is ‘(c) Vibrate in a pattern determined by the form of the traveling wave in the fluids of the cochlea.’

Note:
- The outer ear serves the function of collecting sound from all sources in various directions.
- The middle ear contains three tiny ear ossicles that vibrate according to the energy of a sound wave and also amplify it.
- The inner ear converts the vibrations of the compressional wave introduced within the fluid into the nerve impulses that can be transmitted to the brain.