Which inner ear structures detect linear acceleration and gravity?

Which inner ear structures detect linear acceleration and gravity?

• A. Semicircular canals
• B. Otolith organs
• C. Cochlea
• D. Eustachian tube

Answer: (B)

Otolith organs in the inner ear detect linear movement and head position relative to gravity. These two structures—the utricle and saccule—have hair cells embedded in a gelatinous layer that’s topped with otoliths, tiny crystals of calcium carbonate. When you move in a straight line or tilt your head, the inertia of the otoliths causes the gel layer to shift, bending the hair cells. This bending alters the rate at which these cells send signals to the brain, letting you sense linear acceleration and how your head is oriented in space. The semicircular canals, by contrast, respond to rotational, not linear, motion through movement of fluid inside their ducts. The cochlea handles hearing, translating vibrations into neural signals, and the Eustachian tube mainly equalizes middle-ear pressure.

Otolith organs in the inner ear detect linear movement and head position relative to gravity. These two structures—the utricle and saccule—have hair cells embedded in a gelatinous layer that’s topped with otoliths, tiny crystals of calcium carbonate. When you move in a straight line or tilt your head, the inertia of the otoliths causes the gel layer to shift, bending the hair cells. This bending alters the rate at which these cells send signals to the brain, letting you sense linear acceleration and how your head is oriented in space. The semicircular canals, by contrast, respond to rotational, not linear, motion through movement of fluid inside their ducts. The cochlea handles hearing, translating vibrations into neural signals, and the Eustachian tube mainly equalizes middle-ear pressure.