Otolithic organ (composed of Utricle and Saccule)

The otolithic organ consists of the utricle and saccule in the vestibular labyrinth of the inner ear. Both contain hair cells embedded in a gelatinous layer topped by calcium carbonate crystals (otoconia/otoliths). These organs sense linear acceleration (horizontal via utricle, vertical via saccule) and head position. When the head moves or tilts, gravity acts on the otoconia, causing the gelatinous membrane to shift. This bends the underlying hair cells, converting mechanical stimuli into electrical signals sent to the brain via the vestibular nerve (cranial nerve VIII). This system is fundamental for maintaining balance, spatial orientation, and equilibrium. Dysfunction or damage can lead to dizziness, vertigo, motion sickness, and other balance disorders. The term "otolithic organ" should not be used to refer to a molecule or receptor; its biological role is as a sensory detector in the vestibular system, not as a druggable target.

Other names

Otolith organsvestibular otolithsutricle and sacculegravity sensorsmaculae of the vestibular system