Vertical semicircular canal pathways

Anterior Canal Pathway Afferents that originate in the anterior canals (AC) of the peripheral labyrinth first synapse in the ipsilateral vestibular nucleus. Three pathways exist: 1) medial longitudinal fasciculus (MLF) - right AC afferents to right medial vestibular nucleus (MVN), decussate and ascend via the left MLF to the elevator muscles (right superior rectus [SR] and left inferior oblique [IO]) 2) ventral tegmental tract (VTT) - right AC afferents to right caudal superior vestibular nucleus (MVN), decussate and ascend via the left VTT to the elevator muscles 3) brachium conjunctivum (BC) - right AC afferents to right rostral SVN, ascend (more laterally) and decussate via the BC to the elevator muscles LVN=lateral vestibular nucleus Posterior Canal Pathway Afferents that originate in the posterior canals (PC) of the peripheral labyrinth first synapse in the ipsilateral vestibular nucleus. One pathway exists: 1) MLF - right PC afferents to right MVN, decussate and ascend via the left MLF to the depressor muscles (right superior oblique [SO] and left inferior rectus [IR]