trochlear nucleus

Introduction

Somatic motor nucleus of CN 4.

• paired nuclei located in midbrain near aqueduct of Sylvius just inferior to the occulomotor nucleus at the level of the decussation of the superior cerebellar peduncles & the substantia nigra
• Trochlear nerve fibers cross over & exit the brainstem posteriorly, an exception to the rule that cranial nerves do not cross over & exit anteriorly
• fibers originating in the trochlear nucleus innervate the superior oblique

More general terms

• cranial nerve nucleus

Additional terms

• trochlear nerve (CN IV)