Anatomy of the Cochlea

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Questions and Answers

What is the function of the basilar membrane in the cochlea?

To produce sound waves

To regulate the endolymph

To transmit sound vibrations to the organ of Corti (correct)

To support the spiral ligament

What is the name of the triangular tunnel formed by the outer and inner pillar cells in the organ of Corti?

Corti's tunnel

The cochlear duct

The tunnel of Corti (correct)

The spiral lamina

What type of cells cover the outer wall of the cochlear duct?

Cuboidal epithelial cells

Pseudostratified columnar epithelial cells (correct)

Squamous epithelial cells

Flat epithelial cells

What is the role of the stereocilia in the hair cells of the organ of Corti?

To detect sound vibrations and convert them into electrical signals Signup and view all the answers

What is the function of the outer and inner phalangeal cells in the organ of Corti?

To support the hair cells Signup and view all the answers

What is the type of epithelium that covers the roof of the cochlear duct?

Flat epithelial cells Signup and view all the answers

What is the primary function of the basilar membrane?

To transmit vibrations to the peri-lymph of the scala tympani Signup and view all the answers

What type of cells are flask-shaped and responsible for transmitting sound signals?

Inner hair cells Signup and view all the answers

What is the purpose of the tectorial membrane?

To make contact with the stereocilia of the hair cells Signup and view all the answers

What is the function of the stereocilia in the hair cells?

To receive hearing impulses Signup and view all the answers

What is the purpose of the border cells in the organ of Corti?

To provide structural support to the hair cells Signup and view all the answers

What is the function of the cochlear duct?

To transmit vibrations to the peri-lymph of the scala tympani Signup and view all the answers

What is the purpose of the Hansen's cells?

To provide structural support to the hair cells Signup and view all the answers

What is the primary function of the outer hair cells?

To amplify sound waves Signup and view all the answers

What is the main function of the maculae sacculi and utriculi?

Detects the linear movements of the head Signup and view all the answers

What is the composition of the otolithic membrane?

Gelatinous membrane with calcium carbonate crystals Signup and view all the answers

What is the role of the stereocilia in hair cells?

They are embedded in the otolithic membrane and detect movements Signup and view all the answers

What is the type of epithelium that lines the membranous labyrinth?

Simple squamous epithelium Signup and view all the answers

What is the function of the crista ampullaris?

Detects the rotational movements of the head Signup and view all the answers

What is the type of hair cells found in the maculae sacculi and utriculi?

Both Type I and Type II hair cells Signup and view all the answers

What is the composition of the endolymph?

A clear fluid containing sodium ions Signup and view all the answers

What is the structure of the ampulla?

A dilated terminal part Signup and view all the answers

Study Notes

Cochlea

The cochlea is bounded by the basilar membrane (floor), vestibular membrane (roof), and stria vascularis (outer wall).
The organ of Corti lies on the basilar membrane and is responsible for hearing.
It bathes in endolymph.

Organ of Corti

Consists of supporting cells (outer and inner pillar cells, outer and inner phalangeal cells, border cells, and Hansen's cells) and sensory (hair) cells (inner and outer hair cells).
Inner hair cells are flask-shaped, while outer hair cells are cylindrical.
Each cell has apical stereocilia that receive hearing impulses and basal parts that synapse with the dendrites of bipolar nerve cells.

Tectorial Membrane

A jelly-like membrane overhanging the organ of Corti, in contact with the stereocilia of the hair cells.

Mechanism of Hearing

Sound waves vibrate the eardrum, stapes bone, and oval window, transmitting vibrations to the basilar membrane.
This movement causes stereocilia to bend, exciting nerve endings and generating a nerve impulse.

Vestibule

Part of the inner ear.
Contains the membranous labyrinth (saccule and utricle).

Membranous Labyrinth

Contains endolymph and is lined with simple squamous epithelium.
The epithelium is modified to form maculae sacculi and utriculi.

Maculae Sacculi and Utriculi

Neuro-epithelial thickenings in the walls of the saccule and utricle.
Consists of supporting columnar cells and sensory (hair) cells (type I and type II).
The apex of hair cells has a kino-cilium and many stereocilia.

Otolithic Membrane

A gelatinous membrane covering the macula, containing calcium carbonate crystals.
The stereocilia and kino-cilia are embedded in it.

Function of Maculae Sacculi and Utriculi

Detects linear movements of the head.

Semicircular Canals

Part of the inner ear, consisting of three membranous semicircular ducts.
Contains endolymph and is lined with simple squamous epithelium.

Crista Ampullaris

A neuro-epithelial structure in the wall of the ampulla of the semicircular ducts.
Detects angular movements of the head.

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Description

This quiz covers the structure of the cochlea, including its boundaries and components. Learn about the floor, roof, and outer wall of the cochlea and their features.