Question

Inner ear contains all except (a) Reissner's membrane (b) Basilar membrane (c) Cochlea (d) Stapes

Short answer

The component not found in the inner ear among the given options is the Stapes.

Step-by-step solution

Understand the structure of the inner ear

The inner ear is the innermost part of the ear, which contains various crucial structures for hearing and balance. This includes Reissner's membrane, Basilar membrane, and the Cochlea.

Identify the outlier

Among the provided options, the Stapes (Option D) is the only component that is not a part of the inner ear. The Stapes is actually a part of the middle ear and it is the smallest bone in the human body. This bone plays a key role in transmitting sound vibrations from the air to the inner ear.

Key concepts

Inner Ear Structures

In understanding the inner ear's anatomy, it's essential to explore its main components that play a significant role in both hearing and balance. The inner ear is comprised of several key structures:

• Cochlea: This is a spiral-shaped organ responsible for converting sound vibrations into neural signals, which are then interpreted by the brain as sound. The Cochlea contains a fluid-filled chamber that aids this conversion process.


• Reissner's Membrane: Also known as the vestibular membrane, it separates the cochlear duct from the vestibular duct. It helps maintain the ionic composition of the fluids in these inner compartments.


• Basilar Membrane: Found within the Cochlea, this membrane supports the sensory hair cells that detect sound vibrations. These hair cells convert mechanical energy from sound waves into electrical signals.

These structures work cohesively to facilitate not just hearing but also maintain balance, contributing to our overall sensory experience. The inner ear is a marvel of biological engineering, housing these intricate components within its spiral labyrinth.

Middle Ear Components

The middle ear is an air-filled space that contains a crucial set of bones and structures essential for sound transmission. The primary components of the middle ear include:

• Tympanic Membrane: Commonly known as the eardrum, it acts as a barrier and transmits sound vibrations from the outer ear to the bones within the middle ear.


• Ossicles: The smallest bones in the human body, which consist of three parts:
  • Malleus (Hammer): Attached to the eardrum and transmits vibrations to the Incus.
  • Incus (Anvil): Transmits vibrations from the Malleus to the Stapes.
  • Stapes (Stirrup): The smallest bone, it connects to the inner ear and transfers vibrations to it.


• Eustachian Tube: This canal connects the middle ear to the nasopharynx, helping to equalize air pressure on both sides of the tympanic membrane.

These components are vital for transforming air sound vibrations into mechanical movements that the inner ear can detect.

Hearing Mechanism

The hearing mechanism is a sophisticated process involving both mechanical and neural components, translating sound waves into meaningful signals perceived by the brain. This complicated process starts when sound waves enter the ear through the following stages:

• Sound wave entrance: Sound waves travel through the outer ear canal, striking the tympanic membrane in the middle ear.


• Vibration transmission: The tympanic membrane vibrates along with the ossicles (Malleus, Incus, Stapes), amplifying the sound and transmitting it to the oval window of the inner ear.


• Inner ear processing: Inside the Cochlea, these vibrations create waves in the cochlear fluid, moving the Basilar Membrane.


• Signal conversion: The movement stimulates hair cells on the Basilar Membrane to convert mechanical energy into electrical impulses.


• Signal interpretation: These electrical signals travel along the auditory nerve to the brain, where they are interpreted as sound.

Each step in this process is crucial, as any disruption could affect hearing ability. The hearing mechanism exemplifies how precise our bodily systems must be to function correctly, translating simple sound waves into complex understandings.