During head tilt, how do the otoconia behave?

• A. They move and stimulate hair cells
• B. They dissolve
• C. They remain stationary
• D. They shrink

Answer: (A)

During head tilt, gravity causes the otoconia crystals in the otolith organs to shift within the gelatinous otolithic membrane. That movement deflects the hair cell stereocilia, bending them and stimulating the hair cells (increasing or decreasing their firing depending on direction). This is how the vestibular system converts head position relative to gravity into neural signals about linear acceleration and tilt. They don’t dissolve, remain stationary, or shrink—their inertia under gravity produces the deflection that activates the hair cells.