Recall that the vestibulo-ocular reflex enables the eyes to remain fixed on targ

Question

Recall that the vestibulo-ocular reflex enables the eyes to remain fixed on target and that extrinsic eye muscles are innervated by brainstem -motor neurons. What role does the medial longitudinal fasciculus play in the vestibulo-ocular reflex?

central integration

links the vestibular nuclei with brainstem motor nuclei

5. Descending projections from the vestibular nuclei enable postural adjustments of the head and body. Any stereotypical change in head position that promotes balance is mediated by the vestibulo-cervical reflex. This name stems from the fact that most of the -motor neurons that control the position of the head are located in the motor nuclei of the

brainstem

cervical cord

6. Any stereotypical change in body position that promotes balance is mediated by the vestibulo-spinal reflex. Does this reflex implement the -loop?

yes

no

Explanation / Answer

4. links the vestibular nuclei with brainstem motor nuclei.

Vestibular nerve fibers project to the medial and lateral vestibular nuclei, these nerve fibers originate in the left horizontal semicircular canal. From the medial vestibular nucleus, excitatory fibers pass towards the contralateral abducens nucleus and divides into two outputs. One of the two outputs is a motor pathway is involved in the contraction of the lateral rectus of the right eye. While, the other output is an excitatory projection that after crossing the midline ascends to the left oculomotor nucleus via the medial longitudinal fasciculus thus, activates neurons that cause contraction of the medial rectus of the left eye.  

5. Brain stem

The -motor neurons that control the position of the head and facial movements are located in the motor nuclei of the brainstem, and those that control the body and limb movement are located in the anterior horn of the spinal cord.

6. Yes.

Vestibulo-spinal reflexes are controlled by extensive feedback loops.

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