short notes about vestibular system

1. Presented By-
Abhradip Khanra
B.Pharm(1st year)
Sec-A
Roll No-15
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2. Contents
Introduction
Macula
The Semicircular Canals
The Vestibular Fluids
Vestibular Pathways
Conclusion
References
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3. Introduction
Vestibular system, apparatus of the inner ear involved
in balance.
The vestibular system consists of two structures of the
bony labyrinth of the inner ear, the vestibule and the
semicircular canals, and the structures of the
membranous labyrinth contained within them.
It is a sensory organ that detects sensation of
equlibrium.
Vestibular apparatus plays an important role in
maintaining posture and equilibrium.
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4. Macula
Located in utricle-floor(horizontal) & saccule-posterior
wall(vertical).
The hair cells are embedded in a gelatinous
layer impregnated with crystals of CaCO3 called
OTOLITH MEMBRANE.
A filamentous network connects the lower sur
face of otolithic membrane with sensory epithe
lium called SUBCUPULAR MESHWORK.
A virtual curved line called STRIOLA divides
utricle hair cells into medial & lateral groups.
& saccular hair cells into ventral & dorsal groups
with opposite orientation.
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5. The Semicircular Canals
They are three in number: the external or horizontal,the superior
or frontal , and the posterior or sagittal . One end of each canal
opens out into a larger space known as ampulla,the other end is
even.
The ampulla of each membranous canal
contains a ridge.
The crista ampullaris,which is a recep
tor,i.e. a nerve ending consisting of a
highly-differentiated neuroepithelium
or hair and supporting cells.
The receptors of the vestibule and semicir
cular canals are the peripheral nerve ending
of the vestibular analysator.
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6. The Vestibular Fluids
Perilymph
 In the bony labyrinth.
 It is similar to the extracellular fluid.
 (Low potassium,high sodium).
Endolymph
 In the membranous labyrinth.
 It is similar to the intracellular fluid.
 (High potassium,low sodium).
 It is continuous with the endolymph of the cochlea.
 It is secreted by epithelial cells continuously and drains from the
inner ear into the venous sinus in the dura mater of the brain.
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7. Vestibular Pathways
Nerve ending from crista & macula have their cell body in
bipolar cells of vestibular ganglia(FIRST ORDER
NEURON),central axons of vestibular nerve enter medulla
ventral to inferior cerebellar peduncle.
Axons divide into ascending &descending branches which
end in four-part vestibular nuclei(SECOND ORDER
NEURON)on same side : Medial Nuclei , Lateral Nuclei,
Inferior Nuclei ,Superior Nuclei.
In addition to the main afferents from vestibular
apparatus,the vestibular nuclei also receive inhibitory
fibres from cerebrum & cerebellum.
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8. Conclusion
Vestibular centers in the brainstem, cerebellum, and
cerebral cortex function to integrate sensory
information from the peripheral vestibular organs,
visual system, and proprioceptive system to allow for
proper balance and orientation of the body in its
environment.
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9. References
Last sited from
https://www.slideshare.net/mobile/vacagodx/vestibul
ar-system-3550870
https://www.slideshare.net/mobile/DiaaSarahin/anat
omy-physiology-of-vestibular-system
on 29/01/2021
 Ross and Wilson - Anatomy and Physiology in
Health and Illness, 12th edition . Page No-(131-214)
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