Organ of corti
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Organ of Corti. Organ of Corti (limbus). Organ of Corti (tectorial memb.). Organ of Corti (inner hair cells). Organ of Corti (outer hair cells). Organ of Corti (spriral lamina). Organ of Corti (habenula perforata). Organ of Corti (supporting cells). Organ of Corti (basilar membrane).

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Organ of Corti

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Organ of corti

Organ of Corti


Organ of corti limbus

Organ of Corti (limbus)


Organ of corti tectorial memb

Organ of Corti (tectorial memb.)


Organ of corti inner hair cells

Organ of Corti (inner hair cells)


Organ of corti outer hair cells

Organ of Corti (outer hair cells)


Organ of corti spriral lamina

Organ of Corti (spriral lamina)


Organ of corti habenula perforata

Organ of Corti (habenula perforata)


Organ of corti supporting cells

Organ of Corti (supporting cells)


Organ of corti basilar membrane

Organ of Corti (basilar membrane)


Organ of corti viiith nerve

Organ of Corti (VIIIth nerve)


More on cells

More on Cells

  • Hair Cells

    • Outer Hair Cells

    • Inner Hair Cells

  • Supporting Cells (modiolus to stria vascularis)

    • Vestibular Lip

    • Border Cells of Held

    • Inner Phalangeal Cells

    • Rods of Corti (Pillar Cells)

    • Dieters Cells

    • Hensons Cells

    • Claudius and Boettcher Cells


Insert zemlin page 471

Insert zemlin page 471


Cross section showing hair cells and supporting cells

Cross section showing hair cells and supporting cells

  • Note: modiolus is to the right of slide


Inner hair cells

Inner Hair Cells

  • Inner Hair Cells (see previous slide)

    • Jug shaped

    • Larger than OHCs

    • Single Row

    • 3000 to 4000 in number

    • Innervated by both afferent and efferent fibers

  • IHC cilia

    • 50 to 70 cilia per cell in U shaped configuration.

    • Cilia not embedded in tectorial membrane


Outer hair cells

Outer Hair Cells

  • Outer Hair Cells (see previous slide)

    • Tube shaped

    • Smaller than IHCs

    • 3 rows except at apical end where it increases to 4 and then 5 rows

    • 12,000 to 13,000 in number

    • Innervated by both afferent and efferent fibers

  • OHC cilia

    • 58 cilia at apical end to 150 per cell at basal end in W or V shaped configuration.

    • Cilia embedded in tectorial membrane


Cilia

Cilia

  • Photo showing U shaped configuration of IHC (top) and W or V shaped configuration of OHC (bottom)


Hair cell structures

Hair Cell Structures


Hair cell stereocilia

Hair Cell (stereocilia)


Hair cell dendrite

Hair Cell (dendrite)


Hair cell synaptic cleft

Hair Cell (synaptic cleft)


Hair cell cuticle

Hair Cell (cuticle)


Hair cell reticular lamina

Hair Cell (reticular lamina)


Hair cell photo

Hair Cell (photo)

  • Outer Hair cells showing the stereocilia, reticular lamina and cuticle.


Hair cell efferent axon

Hair Cell (efferent axon)


Organ of corti

Cross-section of the auditory nerve


Organ of corti

Auditory Nerve Fiber Bundle

High frequency fibers: outer auditory nerve

Low frequency fibers: inner auditory nerve

Tonotopicity in the auditory nerve

Mapping of frequency to place along the basilar

membrane preserved in central auditory nervous system

fiber CF

200

500

1000

Hair cells

Apex: wide and loose

Basilar membrane

Base: narrow and tight


Auditory pathways

Auditory Pathways


Auditory pathways1

Auditory Pathways


Auditory pathways2

Auditory Pathways


Effects of decusation

Effects of decusation


Organ of corti

Central auditory system

StructureFunction/Description

IHC to Auditory Nerve Fiber1st synapse located in the cochlea

Cochlear Nucleus2nd synapse (1st central way station)

Superior Olivary Complex3rd synapse, Convergence of inputs from two ears, Delay line, localization

Inferior Colliculi4th synapse, multi-sensory integration

Medial Geniculate Body5th synapse, located in the thalamus

Auditory Cortex6th synapse


Organ of corti

Sagittal view of the brain


Organ of corti

Primary auditory cortex is tonotopically organized


Organ of corti

fiber CF

8000 Hz

4000

2000

fiber CF

200

500

1000

fiber CF

8000 Hz

4000

3000

fiber CF

200

500

700

Plasticity: flexibility,

the ability to adapt to

new situations.

Tonotopically organized

Auditory Cortex

Normal

Hair cell death, 1-2 kHz


Organ of corti

Central auditory pathways: review


Organ of corti

Acoustic Reflex Arc

  • Acoustic reflex:

  • Contraction of the stapedius and tensor tympani muscles occurs at high intensity levels

  • The response is bilateral

  • Some functions:

    • Protection from intense sounds

    • Smoothing of the frequency response of the outer and middle ears


Organ of corti

Acoustic Reflex Arc

Midline of the brain

Efferent

(ipsilateral pathway)

Efferent

(contralateral pathway)

STIMULUS

Afferent


Inner ear fluids

Inner Ear Fluids


Blood supply

Blood Supply


Summary

Summary


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