The Vestibular System

Question 1

The receptors of the utricle, saccule and semicircular canals, shown here, are examples of?
A. Chemoreceptors.
B. Mechanoreceptors.
C. Nociceptors.

Answer 1

Mechanoreceptors

Question 2

At which level, in the photograph, do the primary vestibular axons enter the brain stem?
A. The caudal medulla.
B. The pontomedullary junction.
C. The mid-pons.
D. Near the mammillary bodies in the interpeduncular fossa.

Answer 2

The pontomedullary junction.

CN VI, VII, and VIII enter/exit the brain stem at the junction of the medulla and pons.

Question 3

The vestibular system can be stimulated or irritated by an infection of the inner ear or by a tumor (arrow) pressing on the vestibulocochlear nerve. Which of the following would NOT occur?
A. Decreased auditory acuity.
B. Vertigo.
C. Tinnitis.
D. Loss of facial sensation.
E. Nausea.

Answer 3

Loss of facial sensation.

Facial sensation, mediated by CN V would not be affected by a tumor compressing CN VIII, unless the tumor is large enough to press on CN V or affect the descending nucleus and tract of V in the medulla.

Question 4

This structure:
A. Signals angular acceleration.
B. Is important for conjugate eye movements.
C. Signals orientation with respect to gravity.
D. Is bathed with perilymph.

Answer 4

Signals orientation with respect to gravity

The macula with its otoliths in a gelitinous membrane signals gravity and acceleration changes by deforming the kinocilia.

Question 5

Information from these nuclei reach consciousness in the:
A. Inferior colliculus.
B. Inferior thalamus near VPL.
C. Cortex between intraparietal and postcentral sulci.
D. Cerebellum.

Answer 5

Cortex between intraparietal and postcentral sulci.

The area behind the head region of the postcentral gyrus which represents the head.

Question 6

In the absence of bilateral vestibular function, orientation of the body in space is possible due to:
A. Visual input.
B. Auditory input.
C. Dorsal column input.
D. Both A and C.
E. A, B, and C

Answer 6

Dorsal column input

Both visual and proprioceptive are important. At night, a person without dorsal column functions is severly handicapped.

Question 7

The medial vestibulospinal tract and MLF aid in:
A. Orienting toward visual stimuli.
B. Maintaining visual fixation.
C. Stabilizing the head in space.
D. Vestibulocollic reflex (i.e. head bobbing when you fall asleep in lecture).
E. All of the above.

Answer 7

All of the above

Question 8

What is the dorsal root ganglion equivalent for the vestibular portion of cranial nerve VIII called?
A. Spiral ganglion.
B. Vestibular ganglion.
C. Celiac ganglion.
D. Geniculate ganglion.
E. Semilunar ganglion.

Answer 8

Vestibular ganglion

The vestibular ganglion is the DRG for the vestibular nerve.