The Vestibulospinal Pathway

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The Vestibulospinal Pathway

• Balance.balance...

"Stoop and you'll be stepped on stand tall and
you'll be shot at." - Carlos A. Urbizo
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Introduction

• This somatotopic pathway functions to excite
  extensor motoneurons and inhibit flexor
  motoneurons, contributing to posture control.
• The vestibular nerve sends contributions to the
  medial and lateral vestibular nuclei which give
  rise to the medial and lateral vestibular tracts,
  respectively.

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Distributing the tracts

• The medial tract descends bilaterally in the
  brainstem with the medial longitudinal fasciculus
  and in the ventral funiculus of the rostral
  spinal cord.
• The lateral tract descends ipsilaterally in the
  brain stem and spinal cord.

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The ears arent just for hearing!

• Information regarding angular and linear
  acceleration is transmitted to the brain stem via
  the vestibular portion of CN VIII.
• The vestibular nuclei project mainly to the
  spinal cord, cerebellum, and nuclei of Cranial
  Nerves III, IV, and VI.

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Oculomotor Nucleus Trochlear Nucleus Abducens
Nucleus
Vestibular Nucleii -Lateral -Medial
CN VIII
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Entering the Brain Stem
The vestibular portion of CN VIII enters in the
medulla and sends its fibers around the inferior
cerebellar peduncle to synapse in the medial and
lateral vestibular nuclei.
Inferior Cerebellar Peduncle Lateral
Vestibular Nucleus Medial Vestibular Nucleus
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The Medial Tract
Medial Vestibular Nucleus Medial
Longitudinal Fasciculus Fibers leaving
at Cervical Levels

• The medial tract joins
• the medial
• longitudinal fasciculus
• and provides ipsi and
• contralateral support to
• upper spinal levels.
• It is responsible for
• stabilizing the head
• and coordinating eye
• and head movements.

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The Lateral Tract
Lateral Vestibular Nucleus Fibers
leaving cord at the lumbar level

• The lateral tract continues
• ipsilaterally throughout the
• cord in the ventral part of
• the lateral funiculus.
• This tract is responsible for
• compensatory muscular
• contractions in response to
• body tilt and movement.

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And Now For the Movie.