The semicircular canals and otolith organs are supplied by the peripheral processes of bipolar neurons in the vestibular (Scarpa's) ganglion, located in the internal auditory canal.
The nerve from the ganglion to the brainstem is maintained by schwann cell derived myelin. However, the proximal tip of the nerve and the root-entry zone within the pontomedullary junction are covered by central myelin derived from oligodendrocytes.
The vestibulocochlear ganglion splits into superior and inferior divisions:
- Superior vestibular nerve: superior canal, lateral canal, utricle
- Inferior vestibular nerve: posterior canal and saccule
Figure 1. Superior vestibular nerve supply in green; Inferior vestibular nerve in blue.
Figure 2. The divisions of the 8th cranial nerve, showing supply to the semicircular canals, utricle and saccule, and the cochlea.
Redrawn from: Neupsy Key. The vestibular system. Retrieved from: https://neupsykey.com/the-vestibular-system-4/