Chapter contents
Overview
Origin, central course
Intracranial course
Final innervation
Clinical correlation
Unique features
| Cranial Nerve IV - Trochlear Nerve | Page 3 of 7 |
Origin and central course
The fibers of the trochlear nerve originate from the trochlear nucleus located in the tegmentum of the midbrain at the level of the inferior colliculus.
The nucleus is located just ventral to the cerebral aqueduct. It is readily identifiable by its close association with the myelinated medial longitudinal fasciculus that allows communication between various brainstem nuclei.
Fibers leaving the trochlear nucleus travel dorsally to wrap around the cerebral aqueduct.
All fibers of the two trochlear nerves decussate (i.e. cross) in the superior medullary velum and exit the dorsal surface of the brainstem just below the contralateral inferior colliculus.
Figure 4-3. Origin and central course. Unlabelled version.
