CVT Vestibular System Anatomy & Physiology Techniques 2 — Questions and Answers
Question 1: Which structure in the inner ear contains the macula utriculi and macula sacculi?
- Semicircular canals
- Otolithic organs (Correct answer)
- Cochlear duct
- Endolymphatic sac
Correct answer: Otolithic organs
The otolithic organs (utricle and saccule) each contain a macula, which is a sensory epithelium embedded with otoconia crystals that detect linear acceleration.
Question 2: The type I hair cell in the vestibular system is characterized by its:
- Cylindrical shape with multiple afferent boutons
- Flask shape enclosed by a calyceal afferent nerve ending (Correct answer)
- Direct connection to the efferent nervous system only
- Absence of stereocilia on its apical surface
Correct answer: Flask shape enclosed by a calyceal afferent nerve ending
Type I hair cells are flask-shaped and are enclosed by a calyceal (chalice-shaped) nerve ending that surrounds the base of the cell.
Question 3: Which cranial nerve carries vestibular afferent signals from the inner ear to the brainstem?
- CN VII (Facial nerve)
- CN IX (Glossopharyngeal nerve)
- CN VIII (Vestibulocochlear nerve) (Correct answer)
- CN X (Vagus nerve)
Correct answer: CN VIII (Vestibulocochlear nerve)
The vestibulocochlear nerve (CN VIII) transmits both vestibular and auditory afferent signals from the inner ear to the brainstem.
Question 4: The endolymph fluid within the membranous labyrinth has an ionic composition most similar to:
- Perilymph
- Cerebrospinal fluid
- Intracellular fluid (Correct answer)
- Blood plasma
Correct answer: Intracellular fluid
Endolymph is uniquely high in potassium and low in sodium, resembling intracellular fluid rather than typical extracellular fluids like perilymph or CSF.
Question 5: During head rotation to the right, the right horizontal semicircular canal ampulla experiences:
- Ampullofugal endolymph flow causing inhibition
- Ampullopetal endolymph flow causing excitation (Correct answer)
- No change in hair cell firing rate
- Decreased endolymph pressure only
Correct answer: Ampullopetal endolymph flow causing excitation
Rightward head rotation causes ampullopetal (toward the ampulla) endolymph flow in the right horizontal canal, which deflects the cupula and excites right-side hair cells.
Question 6: The vestibulo-ocular reflex (VOR) stabilizes gaze by generating eye movements that are:
- Equal in direction to head movement
- Opposite in direction and roughly equal in magnitude to head movement (Correct answer)
- Faster than head movement but in the same direction
- Slower than head movement and in the same direction
Correct answer: Opposite in direction and roughly equal in magnitude to head movement
The VOR produces compensatory eye movements opposite to head movement at roughly the same velocity, keeping the visual image stable on the retina.
Question 7: Scarpa's ganglion contains the cell bodies of which neurons?
- Efferent vestibular neurons
- Primary vestibular afferent neurons (Correct answer)
- Secondary vestibular neurons projecting to the thalamus
- Olivocochlear bundle neurons
Correct answer: Primary vestibular afferent neurons
Scarpa's ganglion (vestibular ganglion) houses the bipolar cell bodies of primary afferent neurons that relay signals from the vestibular hair cells to the brainstem.
CVT Vestibular System Anatomy & Physiology Techniques 2
Which structure in the inner ear contains the macula utriculi and macula sacculi?