Sound vibrations enter the cochlea through the:
options: 1) tympanic membrane 2) oval window 3) Eustachian tube 4) auricle 5) round window
The correct answer and explanation is:
Correct Answer: 2) Oval window
The cochlea is a spiral-shaped structure in the inner ear that plays a central role in the process of hearing. Sound vibrations ultimately reach the cochlea after passing through several anatomical structures in the ear. The journey begins at the auricle (also called the pinna), which collects sound waves and directs them into the external auditory canal. These waves strike the tympanic membrane (eardrum), causing it to vibrate.
The vibrations are then transferred to three small bones in the middle ear: the malleus, incus, and stapes. These bones act as a mechanical lever system that amplifies the sound vibrations. The stapes, the last bone in this chain, is attached to a membrane called the oval window, which forms the entrance to the cochlea.
When the stapes moves back and forth, it creates pressure waves in the fluid-filled cochlea by vibrating the oval window. This is the precise point at which sound vibrations enter the cochlea. The movement of fluid within the cochlea stimulates tiny hair cells, which convert the mechanical vibrations into electrical signals that are sent to the brain via the auditory nerve.
The round window, another membrane in the cochlea, acts as a pressure release valve, allowing for the displacement of cochlear fluid when the oval window is pushed inward. The Eustachian tube is not involved in hearing but rather helps equalize air pressure between the middle ear and the atmosphere.
Therefore, the oval window is the correct and specific structure through which sound vibrations enter the cochlea, enabling the process of mechanical energy being transformed into neural signals for auditory perception.