The trochlear nerve innervates the superior oblique muscle that controls eye movement (Clarke et al., 2013).

trochlear nerve somata and the fibres in the trochlear nerve root are labelled with choline acetyltransferase the acetylcholine synthesising enzyme indicating that this nucleus forms part of the cholinergic system in zebrafish. The trochlear nerve root crosses the midline before it exits the medulla oblongata where the optic tectum meets the cerebellum (Mueller et al., 2004).

motor cranial nerve schematic troclear IV.png
isl1 cranial nerves expanded-02.png
isl1 cranial nerves expanded-01.png

Key Publications

Shin-ichi Higashijima, Yoshiki Hotta, and Hitoshi Okamoto
Visualization of Cranial Motor Neurons in Live Transgenic Zebrafish Expressing Green Fluorescent Protein Under the Control of the Islet-1 Promoter/Enhancer.
The Journal of Neuroscience, January 1, 2000, 20(1):206–218

Clark, C., Austen, O., Poparic, I., and Guthrie, S. (2013)
alpha2-Chimaerin Regulates a Key Axon Guidance Transition during Development of the Oculomotor Projection.
The Journal of neuroscience. 33(42):16540-16551.

David Schoppik, Isaac H. Bianco, David A. Prober, Adam D. Douglass, Drew N. Robson, Jennifer M.B. Li, Joel S.F. Greenwood. Edward Soucy, Florian Engert, and Alexander F. Schier,
Gaze-Stabilizing Central Vestibular Neurons Project Asymmetrically to Extraocular Motoneuron Pools.
The Journal of Neuroscience, November 22, 2017 • 37(47):11353–11365 • 11353

Thomas Mueller, Philippe Vernier, Mario F. Wullimann
The adult central nervous cholinergic system of a neurogenetic model animal, the zebrafish Danio rerio
Brain Research 1011 (2004) 156–169