Which part of the vestibular system causes somatogyral illusions?

Which part of the vestibular system causes somatogyral illusions?

• A. Semicircular Canals
• B. Otolith organs
• C. Cochlea
• D. Vestibular nerve

Answer: (A)

Somatogyral illusions come from the angular accelerometers of the inner ear—the semicircular canals. When you rotate your head, endolymph inside these canals lags behind the motion due to inertia. This moving fluid deflects the cupula in the ampulla, bending hair cells and signaling to the brain that rotation is occurring. Even after rotation stops (or starts), the endolymph keeps moving briefly, creating a mismatch between actual motion and what you feel. That mismatch produces the rotational illusory motion characteristic of somatogyral illusions. The otolith organs detect linear acceleration and gravity, leading to different types of illusory sensations (like tilting or forward/backward acceleration), not the rotational ones. The cochlea handles hearing, and the vestibular nerve merely carries these signals to the brain. So the semicircular canals are the source of somatogyral illusions.

Somatogyral illusions come from the angular accelerometers of the inner ear—the semicircular canals. When you rotate your head, endolymph inside these canals lags behind the motion due to inertia. This moving fluid deflects the cupula in the ampulla, bending hair cells and signaling to the brain that rotation is occurring. Even after rotation stops (or starts), the endolymph keeps moving briefly, creating a mismatch between actual motion and what you feel. That mismatch produces the rotational illusory motion characteristic of somatogyral illusions.

The otolith organs detect linear acceleration and gravity, leading to different types of illusory sensations (like tilting or forward/backward acceleration), not the rotational ones. The cochlea handles hearing, and the vestibular nerve merely carries these signals to the brain. So the semicircular canals are the source of somatogyral illusions.