Human Ear: Cochlea (Auditory Organ) , the Reissner՚S Membrane (For CBSE, ICSE, IAS, NET, NRA 2022)

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Cochlea (Auditory Organ)

The coiled portion of the membranous labyrinth which looks like a snail.

This is made up of three canals:

  • Upper vestibular canal or scala vestibule.
  • Middle cochlear duct or scala media.
  • The lower tympanic canal or scala tympani.

The Reissner՚S Membrane

  • It separates scala media and scala vestibule.
  • Also known as the vestibular membrane or the vestibular wall.
  • It creates a compartment in the cochlea filled with endolymph together with the basilar membrane.

Stereocilia

  • It projects from the hair cells and extend till the cochlear duct.
  • The tectorial membrane is the other membrane present above hair cells.
  • The pressure waves are detected using the hair cells present in the cochlea.

Vestibular Apparatus (Equilibrium Organ)

  • It is present above the cochlea and it helps in maintaining the equilibrium.
  • It is present in the membranous labyrinth.
  • Saccule and utricle are the two sacs like chambers along with three circular canals.
    • Saccule and utricle have macula, a projecting ridge.
  • Otoliths are calcium ear stones.
  • Crista ampullaris contain hair cells present in each of the ampulla responsible for sensing angular rotation.

Clinical Significance

Clinical Significance

Vertigo

  • It refers to the inappropriate perception of motion due to dysfunction of the vestibular system.
  • Benign paroxysmal positional vertigo is one common type of vertigo.
    • An otolith is displaced from the ventricles to the semicircular canal.
  • Result in the perception of vertigo:
    • Ménière՚s disease
    • labyrinthitis
    • Strokes
    • Other infective and congenital diseases

Tinnitus

  • When there is no external sound, tinnitus is the hearing sound.
  • It may also sound like a clicking, hiss or roaring though often described as the ringing.
  • Unclear voices or music are heard rarely.
  • The sound may be soft or loud, low pitched or high pitched.
  • The sound causes depression, anxiety, or concentration difficulties in some people.
  • It is not a disease but a symptom that can be caused by noise-induced hearing loss.
    • Some other causes are ear infections, disease of the heart or blood vessels, Ménière՚s disease, brain tumors, emotional stress, etc.

FAQs

Q 1. Is Tinnitus a disease or just a symptom?

Answer: Tinnitus is not a disease and just a symptom may be caused due to a few reasons such as ear infections, disease of the heart or blood vessels, Ménière՚s disease, brain tumors, emotional stress, etc.

Q 2. What is The Reissner՚s membrane?

Answer:

  • The Reissner՚s membrane separates scala media and scala vestibule.
  • Also known as the vestibular membrane or the vestibular wall.
  • It creates a compartment in the cochlea filled with endolymph together with the basilar membrane.

Q 3. What are the three main classification of Physiology of ear?

Answer:

  • The three main classification of Physiology of ear are:
  • The organ of Corti (Cochlea)
    • Performs the hearing function.
  • Maculae (Saccule and Utricle)
    • This is responsible for static equilibrium.
  • Cristae (semicircular canals)
    • This is responsible for dynamic equilibrium.

Q 4. What is Cochlea (Auditory Organ?)

Answer:

  • The coiled portion of the membranous labyrinth which looks like a snail.
  • This is made up of three canals:
    • Upper vestibular canal or scala vestibule.
    • Middle cochlear duct or scala media.
    • The lower tympanic canal or scala tympani.