Which structure is primarily responsible for linear vestibulo-ocular reflex (VOR)?

The structure primarily responsible for the linear vestibulo-ocular reflex (VOR) is the vestibule. The vestibule comprises the utricle and saccule, which are otolithic organs that detect linear acceleration and head position relative to gravity. When the head moves linearly, these structures respond to changes in the position of the otoliths (calcium carbonate crystals) embedded in the gelatinous layer, generating signals that inform the brain about the position and motion of the head.

In response to these signals, the VOR provides a mechanism to stabilize gaze by initiating compensatory eye movements that are equal and opposite to the head motion. This is critical for maintaining visual stability during activities that involve head movements.

While the semicircular canals are involved in detecting rotational head movements (angular acceleration) and contribute to the VOR, they do not play a role in the linear component. The cochlea, responsible for hearing, and the tympanic membrane, linked to sound transmission, are not involved in the vestibulo-ocular reflex pathway. Thus, the vestibule is key for enabling the reflex to function accurately during linear motion.