Check my work Correctly identify the following structures of the sectioned cochlea, Cochlear duct Scala tympani Vestibular membrane Spiral ganglion Basilar membrane Scala vestibuli Added 202 2021 2021 2021 2021 2021 2021 2021 2021 2021 2021 2021 2021 2021 20218 2021 at 2021 at < prev=”” 30=”” of=”” 33=”” hii=”” :=”” next=””>
The correct answer and explanation is:
To correctly identify the structures of the sectioned cochlea, let’s break down each component based on their anatomical features and functions:
Structures of the Cochlea
- Cochlear Duct (Scala Media):
- The cochlear duct is a central membranous chamber within the cochlea.
- It contains the organ of Corti, where auditory sensory cells (hair cells) are located.
- It is filled with endolymph, a fluid rich in potassium ions, crucial for hair cell function.
- Scala Tympani:
- Located below the cochlear duct, it is one of the perilymph-filled chambers.
- It plays a role in transmitting sound waves from the oval window to the round window via the helicotrema (a small opening at the apex of the cochlea).
- Vestibular Membrane (Reissner’s Membrane):
- A thin membrane separating the cochlear duct from the scala vestibuli.
- It helps maintain the ionic composition of the endolymph in the cochlear duct.
- Spiral Ganglion:
- Contains the cell bodies of auditory neurons that transmit signals from hair cells to the brain.
- Located within the modiolus, the central bony axis of the cochlea.
- Basilar Membrane:
- Forms the floor of the cochlear duct and supports the organ of Corti.
- Vibrations here correspond to specific frequencies, with high frequencies detected near the base and low frequencies near the apex.
- Scala Vestibuli:
- A perilymph-filled chamber located above the cochlear duct.
- It begins at the oval window and transmits sound vibrations to the cochlear duct.
Explanation
The cochlea is a spiral-shaped, bony structure essential for hearing. Its function lies in converting sound vibrations into electrical signals processed by the brain. The cochlear duct (scala media) is key to sensory processing, containing the organ of Corti, where hair cells detect sound-induced vibrations. Surrounding the duct are two chambers: the scala tympani and scala vestibuli. Both are filled with perilymph and participate in transmitting mechanical vibrations.
Separating the cochlear duct from these chambers are the basilar membrane and vestibular membrane. The basilar membrane vibrates in response to sound waves, with its varying stiffness enabling frequency discrimination. The vestibular membrane ensures ionic isolation between endolymph and perilymph, critical for maintaining electrochemical gradients required for signal transduction.
The spiral ganglion houses neuronal cell bodies that relay auditory signals to the brain via the auditory nerve. This organization allows precise detection and interpretation of sound frequencies, enabling complex auditory processing.