Organ
Oculomotor nucleus and Edinger-Westphal nucleus
Midbrain neurons controlling eye muscles and parasympathetic output
High-yield
A nuclear lesion can cause bilateral ptosis or weakness beyond the same-side CN III muscles. The name Edinger–Westphal has been applied to different cell groups; distinguish the preganglionic eye pathway from centrally projecting neurons when interpreting detailed anatomy.
Overview
The oculomotor complex lies near the aqueduct at superior-colliculus level. Its motor subdivisions do not map simply to one eye: superior-rectus output crosses, while the central caudal group supplies both eyelid elevators. Nearby preganglionic parasympathetic neurons project through CN III to the ciliary ganglion.
Reference facts
- Location
- Rostral midbrain, near the midline just ventral to the aqueduct, at the level of the superior colliculus.
- Parts
- Somatic motor subnuclei plus nearby preganglionic parasympathetic neurons, often designated EWpg. In humans these parasympathetic neurons are not identical to the entire classically named Edinger–Westphal cell group.
- Relations
- Axons travel ventrally through the tegmentum and emerge between the cerebral peduncles, near the posterior cerebral and superior cerebellar arteries.
- Function
- Motor output serves medial, inferior and superior recti, inferior oblique and levator palpebrae. The parasympathetic pathway controls pupil constriction and ciliary-muscle accommodation after a ciliary-ganglion relay.
Clinical correlation
Damage to emerging CN III fibers together with the adjacent descending motor pathway may cause a third-nerve palsy on the lesion side and limb weakness on the other side. This fascicular pattern is different from the potentially bilateral findings of a nuclear lesion.
Frequently asked questions
Where is the oculomotor nucleus and Edinger-Westphal nucleus located?
The oculomotor nucleus and Edinger-Westphal nucleus lies rostral midbrain, near the midline just ventral to the aqueduct, at the level of the superior colliculus.
What does the oculomotor nucleus and Edinger-Westphal nucleus do?
Motor output serves medial, inferior and superior recti, inferior oblique and levator palpebrae. The parasympathetic pathway controls pupil constriction and ciliary-muscle accommodation after a ciliary-ganglion relay.
What are the parts of the oculomotor nucleus and Edinger-Westphal nucleus?
Somatic motor subnuclei plus nearby preganglionic parasympathetic neurons, often designated EWpg. In humans these parasympathetic neurons are not identical to the entire classically named Edinger–Westphal cell group.