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Vestibular System
Dr. dr. I. Rika Haryono, Sp.K.O
27 April 2023
Jakarta agenda
INTRODUCTION
> 3
Vestibular System:
Structure and Function
> 4
Semicircular Canals:
Sensory transduction
> 5
Otolith organ
> 10
Vestibular pathways
Vestibular Reflexes
Summary
> 13
# introduction
> 3
# introduction
The ability to defend the body with all its supporting
components
Correction of body position before falling
Helps maintain stable retinal imagery during head movement
Keseimbangan tubuh Body balance
> 4
Vestibular Structure Vestibular Structure Hair Cell Receptor
Kinocilia and stereocilia are
embedded in the gelatinous
membrane
The upper part of the
membrane contains calcium
carbonate crystals: otolith
stones
Otolith function: increase
membrane inertia
The lower portion of the hair
cells is in direct contact with
the primary sensory neurons
of the Vestibular nerve Hair Cell Receptor
If stereocilia
approach kinocilia
depolarization
If stereocilia move away from
kinocilia
hyperpolarization Hair Cell Receptor Receptors for hearing and balance are in the ear Vestibular Function:
Provides fast and sensitive information
on changes in position and head
movement
Helps coordinate head and eye
movements and adjusts body posture
Part of the inner ear Vestibular Function: Vestibular Function: Semicurcular Canals: Sensory transduction Otolith Organ
Tilt of the head moves
the otolith due to gravity
and bends the ciliary hair cells
depolarization Otolith Organ
Ciliary changes that open ion
channels Otolith Organ
Contains sensory epithelium: The macula
Inside are hair cells, located in a vertical
position in the saccule and horizontally in
the utricle
In the macula there are 2 types of hair cells:
1 Kinocilia side by side on 1 side with a beam
of Stereocilia. VESTIBULAR PATHWAY VESTIBULAR PATHWAY
The macula detects forward acceleration or deceleration as well as tilt of the head.
Gravity and acceleration cause the otoliths to shift forwards or backwards causing the
gelatinous membrane to also shift, bending the ciliary hairs so that depolarization or
hyperpolarization occurs.
When the stereocilia approach the kinocilia, the tip links between the cilia will open
allowing potassium ions to enter the cell, resulting in reduced membrane negativity
resulting in depolarization.
Subsequent depolarization opens electrically gated channels for calcium ions so that
the inside of the membrane becomes more positive and neurotransmitters are
released (exocytosis) to the primary sensory neurons of the Vestibular nerve action
potential
These sensory neurons synapse in the medulla oblongata or vestibular nuclei
continues without synapsing to the cerebellum.
Meanwhile, those that synapse in the medulla oblongata go to the thalamus and then
to the cerebral cortex to be perceived. Vestibular Reflexes
Vestibulospinal reflexes:
rasa ingin jatuh / falling/ tipping
kontraksi otot otot ekstremitas untuk menyokong postur
Vestibulocollic reflexes:
stabilisasi otot -otot leher untuk menggerakan tubuh dan
mempertahankan kepala .
Vestibulo -ocular reflexes:
mempertahankan bayangan benda selama kepala bergerak . Akan
menyebabkan pergerakan mata secara simultan dengan arah yang
berbeda dengan arah Gerakan kepala .VESTIBULAR REFLEX VESTIBULAR REFLEX Vestibular Reflex
Bila rotasi berlanjut , endolimph yang bergerak akhirnya
menyamai gerakan kepala .
Bila kepala mendadak berhenti , cairan tetap berputar sesuai
rotasi kepala sensasi berputar
Sensasi yang kuat , refleks tubuh ke arah yang berlawanan dengan
arah rotasi untuk kompensasi keseimbangan Vestibular Reflex
Setiap kali kepala berputar tiba -tiba , sinyal yang berasal dari
kanalis semisirkularis akan menyebabkan mata berputar dengan
arah yang berlawanan dengan arah putaran kepala refleks
okulovestibular
Mekanisme Vestibular Untuk Menstabilkan Mata: refleks
okulovestibular Sistem Propioseptor
Menerima informasi berupa variasi modalitas sensoris raba , kinestesia
(sensasi keseluruhan sendi ) dan posisi memberikan kesadaran akan posisi
dari berbagai bagian tubuh dalam ruang
Informasi proprioseptik disalurkan ke atas melalui kolumna dorsalis medula
spinalis.
> Sebagian besar menuju serebelum
> Menuju korteks melalui lemnikus medialis dan radiasi talamus
Information dikirim kembali untuk mencetuskan potensial aksi ke otot
untuk mempertahankan kontrol postural SUMMARY summary
Kontrol Sikap dan Keseimbangan tubuh
Terdiri dari 3 komponen sistem :
Deteksi sensoris dari pergerakan
tubuh
Visual
Vestibular
Somatosensory inputs
(propioseptif )
Integrasi informasi sensorimotor
dalam sistem syaraf pusat (peran
serebelum dan batang otak )
Execution respon musculoskeletal
> 27
# References
Bear MF, Connors BW, Paradiso MA.
Neuroscience. Exploring the brain, 2nd
edition. Lippincott Williams & Wilkins,
Baltimore 2001
Silverthorn DU. Human Physiology an
integrated approach, 4th edition, Pearson
Benjamin Cummings, San Francisco 2006
Sherwood L. Human Physiology from cells
to systems, 5th edition, Thomson
Brooks/Cole, Belmont 2004
28 thank you