The document discusses the vestibular system, which is responsible for maintaining balance and spatial orientation by processing sensory input from head motion and gravitational forces. It describes the major vestibular structures, including the utricle, saccule, and semicircular canals, and their roles in detecting linear and angular movements. Additionally, it outlines the connections between vestibular structures and brain regions that enable reflexes like the vestibuloocular and vestibulospinal reflexes for coordinating balance and eye movement.

1. VESTIBULAR
SYSTEM
Aditya
Johan
Romadhon

2. introduction
A sense of proper sensory processing of head motion and
the coordination of visual and postural movements to
maintain equilibrium
Posture is a subsconcious adjustment of tone in different
muscle so as to maintain balance during displacement of
the body caused by gravity or acceleration
Balance is the ability to maintain the body center of mass
over its base support
The vestibular system is an intricate organization that
involves multiple levels of sensory processing to achieve
this goal

3. Vestibular structures The five major
vestibular
structures are
located in the
inner ear
the utricle
the saccule
and the
lateral,
superior, and
posterior
semicircular
canals

4. Hair cells
(crista ampularis
& macula)
• The vestibular system has two types of sensory neuroepthelium
• Both macula and crista ampullaris structures contain rod-shaped
sensory mechanoreceptors called hair cells
• These receptor cells are embedded in a membrane of
neuroepithelium

5. Hair cells on the neuroepithelium of
the peripheral vestibular organs
carry sensory impulses to primary
processing centers in the brainstem
and the cerebellum.
These areas send input via
ascending and descending
projections to coordinate vital
reflexes, such as the vestibuloocular
reflex and the vestibulospinal reflex
which allow for the proper
orientation of the eyes and body in
response to head motion

6. Tip Link function
(sodium-
potassium pump)
• Hair Cell “tip link” function. When head motion results in
tilting of the stereocilia toward the kinocilium, shifting of the
“tip links” causes mechanical opening of the transduction
channels resulting in an influx of K and depolarization of the
hair cells.
• The bending of the stereocilia away from the kinocilium
decreases the “tip link” tension and results in mechanical
closure of the channel causing hyperpolarization of the hair
cell

7. Dynamic changes of interstereociliary

8. Utricle & saccule
The utricle and
saccule are
structures of the
static labyrinth
that sense the
orientation of
the head in
space
They respond to
linear
acceleration,
gravitational
forces, and tilting
of the head
Each contains a
sensory
neuroepithelium
called the macula
The macula of
the utricle senses
motion in the
horizontal plane
The macula of
the saccule
senses motion in
the vertical plane

9. Semicircular canal
• The semicircular ducts
have the same basic
structure as the bony
semicircular canals in
which they are contained
• They make up the kinetic
labyrinth that senses
angular acceleration or
rotation of the head and
are oriented at right angles
to one another

10. Small structures in the inner ear
make up the vestibular
apparatus and detect head
motion and gravitational forces
on the body
Allow the body to maintain
balance and proper spatial
orientation during movement, as
well as the correct processing of
visual images during motion

11. Vestibular nerve
Axons from the
superior and
inferior divisions
of the vestibular
ganglion merge to
form the
vestibular nerve
It combines with
the cochlear nerve
to become the
vestibulocochlear
nerve
The nerve fibers
travel past the
cerebellopontine
angle and enter
the brainstem at
the
pontomedullary
junction
At this point, the
vestibular nerve
separates from the
cochlear nerve
The majority of the
afferent vestibular
fibers project to
the ipsilateral
vestibular nuclear
complex in the
pons

12. Vestibular nuclear
complex
Some of the nerve fibers project to
the flocculo-nodular lobe of the
cerebellum and the adjacent
vermian cortex

13. • This complex is the primary
processor of vestibular input and
consists of four major nuclei:
medial, superior, lateral, and
inferior
• The medial vestibular nucleus is
the largest and makes up the
medial column
• The lateral column consists of the
superior, lateral, and inferior
vestibular nuclei

14. The medial vestibular nucleus has bilateral descending
projections in the medial vestibulospinal tract to the
cervical spinal cord to allow for the coordination of
head and neck motion
The lateral vestibular nucleus form the lateral
vestibular tract in the ipsilateral spinal cord, functions
in the vestibular spinal reflex by coordinating reflexive
tone in the trunk muscles and proximal extensors of
the limbs to maintain posture and balance
The superior vestibular nucleus, it sends ascending
efferent fibers to the extraocular muscles via the
medial longitudinal fasciculus in order to coordinate
the vestibuloocular reflex
The inferior vestibular nucleus has projections that go
to the other three vestibular nuclei and to the
cerebellum

15. Cerebellum

16. Vestibuloocular
reflex
The vestibuloocular reflex
coordinates eye movement in order
to stabilize retinal images during
head rotation

17. Vestibulooccular reflex test

18. Vestibulospinal reflex
This reflex involves many complex connections which
integrate input from the macula, crista ampullaris,
visual system, and axial and limb muscles by the
brainstem, and cerebellum in order for the
maintenance of posture and balance.
It involves both the lateral and medial vestibular spinal
tracts

19. SEKIAN
&
TERIMAKASIH