Human Anatomy - Kotsan I. Ya. 2009

Peripheral Nervous System
Cranial Nerves
Trochlear Nerve (IV)

The Trochlear nerve (n. trochlearis) is a motor nerve (Figs. 239, 255). The Nucleus of the trochlear nerve (nucleus n. trochlearis) lies beneath the ventral wall of the cerebral aqueduct at the level of the inferior colliculi of the Midbrain tectum.

The trochlear nerves emerge from the Brain substance posterior to the inferior colliculi of the tectal plate, on either side of the frenulum of the superior medullary velum. The nerve curves laterally around the cerebral peduncle and courses anteriorly, passing through the lateral wall of the cavernous sinus. Within the lateral wall of the cavernous sinus, the trochlear nerve initially lies inferior to the Oculomotor nerve and subsequently superior to it. It enters the Orbit via the superior orbital fissure and terminates in the superior oblique Muscle of the eye, which it innervates.

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Fig. 255. NERVES OF THE right orbit (after M. R. Sapin)

1 — frontal nerve; 2 — lacrimal nerve; 3 — Abducens nerve; 4 — ophthalmic nerve; 5 — maxillary nerve; 6 — mandibular nerve; 7 — trigeminal ganglion; 8 — oculomotor nerve; 9 — Optic nerve; 10 — trochlear nerve; 11 — nasociliary nerves



Last update: 08/08/2026

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