Question

Arrange the following in the order of reception and transmission of sound wave from the ear drum: Cochlear nerve, external auditory canal, ear drum, stapes, incus, malleus, cochlea.

Answer 1

Mechanism of hearing :

The following points outlines the mechanism of hearing:-

• The pinna directs the sound waves into the external auditory canal.
• The sound vibrations strike the tympanic membrane or ear drum.
• The eardrum vibrates and transfers the mechanical vibrations to the ear ossicles- malleus, incus and stapes of the middle ear. The ear ossicles increase the amplitude of the vibrations.
• The vibrations are passed through the oval window into the fluid of the inner ear.
• The waves in the endolymph of the scala media of the cochlea induce a vibration in the basilar membrane.
• These movements of the basilar membrane bend the hair cells of the organ of corti, pressing them against the tectorial membrane. This leads to generation of the nerve impulse in the cochlear nerve.
• As a result, neurotransmitters are released to generate nerve impulses in the associated afferent neurons.
• These impulses are transmitted by the afferent fibres via auditory nerves to the auditory area of the cerebral cortex of the brain.
• The nerve impulses are then analyzed and finally the sounds are recognised.

Summary :

The order of reception and transmission of the sound wave from the eardrum is - From the external auditory canal to eardrum,then it is transmitted to ear ossicles (malleus,incus,and stapes),and then to cochlea and cochlear nerve.

Final answer:

$\text{External auditory canal}\to \text{Ear Drum}\to \text{Malleus}\to \text{Incus}\to \text{Stapes}\to \text{Cochlea}\to \text{Cochlear nerve}.$