Question

Which option shows correct sequence for mechanism of hearing?
A. External ear $\to$ Reissner’s membrane $\to$ Tympanic membrane $\to$ Cerebrum
B. External ear $\to$ Fenestra rotunda $\to$ Auditory nerve $\to$ cerebrum
C. External ear $\to$ Tympanic membrane $\to$ Cochlear canal $\to$ Sensory cells of corti $\to$ cerebrum
D. External ear $\to$ Ear ossicles $\to$ Ressiner’s membrane $\to$ Cochlear canal $\to$ cerebrum

Answer 1

Ear consists of 3 parts External, middle and internal ear. The external ear is separated from the middle ear by the tympanic membrane. The internal ear is majorly responsible for perceiving the stimulus and sending the impulse to the brain.

Complete Answer:
Ear consists of three parts, namely external ear, middle ear, and internal ear
The external ear is formed by:
1. Auricle or pinna
2. External auditory meatus

The middle ear or tympanic cavity is a small, narrow chamber situated within the temporal bone. It is also known as tympanum. The middle ear is separated from the external auditory meatus by the tympanic membrane.
The middle ear consists of the following structures:
1. Auditory ossicles
2. Auditory muscles
3. Eustachian tube.

Auditory ossicles are the three miniature bones, which are arranged in the form of a chain, extending across the middle ear from the tympanic membrane to the oval window. Auditory ossicles are:
i. Malleus
ii. Incus
iii. Stapes.
- The internal ear or labyrinth is a membranous structure, enclosed by a bony labyrinth in the petrous part of the temporal bone. It consists of the sense organs of equilibrium and hearing. The cochlea is the sense organ for hearing. The sense organ for equilibrium is the vestibular apparatus.
- The cochlea is a coiled structure like a snail’s shell. The organ of Corti is the receptor organ for hearing. It is the neuroepithelial structure in the cochlea. The organ of Corti is made up of sensory elements called hair cells.
- Sound waves travel through the external ear and produce vibrations in the tympanic membrane. Vibrations from the tympanic membrane travel through the malleus and incus and reach the stapes resulting in the movement of stapes. Movements of stapes produce vibrations in the fluids of the cochlea. These vibrations stimulate the sensory hair cells in the organ of Corti. This causes the generation of action potential (auditory impulses) in the auditory nerve fibers. When these auditory impulses reach the cerebrum, the perception of hearing occurs.

So, the correct answer is C.

Note: During the process of hearing, the ear converts the energy of sound waves into action potentials in auditory nerve fibers. This process is called sound transduction.