After entering the brainstem, vestibular afferents first project to which structure?

• A. Cerebellum
• B. Vestibular nuclei in the brainstem (pons/medulla)
• C. Thalamus
• D. Primary visual cortex

Answer: (B)

Vestibular afferents entering the brainstem first synapse in the vestibular nuclei, a group of nuclei in the pons and medulla. This is where initial processing and integration of signals from the semicircular canals and otolith organs occur, setting up reflexes and coordinated responses. From there, info spreads to other areas: to the spinal cord via vestibulospinal pathways for balance and posture, to the ocular motor nuclei via the vestibulo-ocular reflex to stabilize gaze, and onward to the thalamus and cortex for perception. The cerebellum also receives input and helps fine-tune responses, but it is not the first stop. The primary visual cortex is not part of this initial vestibular processing.