Vestibular system podcasts Flashcards
How many vestibular nuclie are ther
4
Where are the vestibular nuclie located
2 in caudal pons
2 in Rostral medulla
What 2 vestibular nuclie lie in the Caudal pons
Superior vestibular nucleus
Lateral vestibular nucleus
What 2 vestibular nuclei lie in the rostral medulla
Medial vestibular nucleus and Inferior vestibular nucleus
Where are sensory nuclei located on the brainstem?
on the side of the brainstem
Lateral Vestibulospinal Tract
• Function:
Maintains balance and posture
Route of Lateral Vestibulospinal Tract
• Route: Pathway descends ipsilaterally from lateral vestibular nucleus to all spinal cord levels
Mechanism of Lateral vestibulospinal tract
• Mechanism: Excites extensor muscles of the neck, back and lower limbs (antigravity muscles)
Medial Vestibulospinal Tract
• Functions:
Adjusts head position in response to postural changes
Pathway of Medial Vestibulospinal Tract
• Pathway descends bilaterally from medial vestibular nucleus to cervical spinal cord levels Coordinates eye movements with each other
What does the medial vestibulospinal tract do
• Pathway projects superiorly and bilaterally along medial longitudinal fasciculus (MLF) from vestibular nuclei to the paramedian pontine reticular formation (PPRF).
a. The PPRF projects to the ipsilateral abducens nucleus which, in turn, projects to the contralateral oculomotor nucleus
• The eyes are yoked together resulting in conjugate horizontal gaze.
a. Coordinates eye movements to compensate for head movements (i.e. the vestibuloocular reflex - VOR)
• The VOR maintains eye position during head turning.
The vestibuloocular reflex (VOR)
coordinates eye movemtns to compensate for eye movements
The VOR is done through
the Medial Vestibulospinal Tract
Tract responsible for coordinating eye movements with each other
Medial vestibulospinal tract
keeps eyes yolked together
Medial vestbulonspinal tract
What two places to the Median Vestibular nucleaus send axons to?
To cervicle spinal cord to have contol over the SCM via CN XI and up to the Medial Longitudinal Fasiculus because there are cranial verve nuclie that control ocular eye movment
Where do Lateral vestibular nuclie get info from?
From the Flocculous on cerebellum and from CNVIII about body position
Where do Lateral Vestibulospinal tracts go?
descend ipsilaterally to all sp cd levels to innerate antigravity muscles and inhibit flexor muscles
Pathway from medial vestibulospinal tracts projects superiorly and bilaterally along medial longitudinal fasciculus (MLF) from vestibular nuclei to the
paramedian pontine reticular formation (PPRF).
Each abducens nucleus is in communication via _____ with the contralateral oculomotor nucleus
Medial longitutinal fasiculus
The eyes end up being yoked together resulting in
conjugate horizontal gaze
What keeps your eyes focused on ojbect as you move your head?
vestibulococular reflex
you can maintain foveation as you move your head
The ______ projects to the ipsilateral abducens nucleus which, in turn, projects to the contralateral oculomotor nucleus
PPRF
Semicircular canals detect head mvmt toward the left and send signals to
vestibular nuclei
Vestibular nuclei project to brainstem nuclei that control
extraocular eye muscles
Rhythmic oscillations of the eyeballs
Nystagmus
Rotation of the head causes
(rotary nystagmus)
Observing a moving object when the head is stationary causes
(optokinetic nystagmus)
Temperature-generated convection currents in semicircular canal endolymph causes
(caloric nystagmus)
Warm water in left ear will give us _____ beating nystagmus
left
Cold water in left ear results in ______ beating nystagmus
right
Involuntary movemnt of a patients eye to an equal extent but in opposite direction of a head turn indicates
normal VOR thus central vestibular pathways are working properly and the brainstem is functioning
