Vestibular system

Question 1

What is the purpose of the vestibularspinal tract off of the vestubulor nuclei?

Answer 1

These tracts go to muscles from the spinal cord. So muscles below our head receive input form vestibular nuclei as well

• This influences the movement of our body

Question 2

What is the purpose of the ascending tract of Medial longitudinal fasciculus?

Answer 2

It coordinates the movement of CN III, IV, VI

CN III: Oculomotor

CN IV: Trochlear

CN VI: Abducent

• controlling the motor functions of the eye originating from the vestibular nuclei

Question 3

If you lesioned all of CN VIII what would your symptoms be?

Answer 3

• A lesion that takes out all of CN VIII closer to the medulla (not in the periphery) will give you unilateral deafness and problems with your vestibular system
• where the pointer is
• so if you have vestibular and cochlear problems you know its more inwards lesion

Question 4

The vestibulospinal system contributes to:

Answer 4

Balance

Question 5

What are the purposes of the three neurons in vestibular?

Answer 5

Neuron 1: vestibular ganglion neurons have axons that extend from hair cells in the vestibular apparatus to vestibular nuclei via the vestibular portion of cranial nerve VIII

• the vestibular nuclei are found at the junction of the pons and the medulla

Neuron 2: neurons of the lateral and medial vestibular nuclei have axons that descend in the lateral vestibulospinal tract and descending components of the medial longitudinal fasciculus (MLF) to the ventral horn of the spinal cord, respectively

• MLF projection primarily to cervical areas

Neuron 3: Lower motor neurons of the ventral horn of the spinal cord terminate on muscles

Question 6

What are the sensory receptors of the vestibular system?

Answer 6

Hair cells

Question 7

Where are hair cells found?

Answer 7

• In the maculae of the urticle and saccule and the cristae of the semicircular duct ampullae

Question 8

• Hair cells contain _____ cilia
• Hair cells are embedded in a ______
  
  • This mass is called the _____ in semicircular canals
    
    • it contains crystals of calcium salts called otoliths in the urticle and sacule

Answer 8

• Hair cells contian long cilia
• Hair cells are embedded in a jellylike mass
  
  • this mass is called the cupula

Question 9

Hair cells activate ____ vestibular neuronal axons by:

Answer 9

• Hair cells activate primary vestibular neuronal axons by releasing a chemical substance when the cilia are deformed