Edinger-Westphal nucleus definition

A small group of preganglionic parasympathetic motor neurones in the midline near the rostral pole of the oculomotor nucleus of the midbrain; the axons of these motor neurones leave the brain with the oculomotor nerve and synapse on the cells of the ciliary ganglion which in turn innervate the sphincter muscle of the pupil and ciliary muscle. Destruction of this nucleus or its efferent fibres causes maximal paralytic dilation of the pupil; also demonstrated to project fibres to lower levels of the brainstem and all spinal levels.

(05 Mar 2000)