Westphal-Edinger Nucleus

WESTPHAL-EDINGER NUCLEUS (K. Westphal-Edinger), belongs to the parasympathetic system, is located in the midbrain tegmentum, below the cerebral aqueduct, medially and posterior to the main nucleus of the oculomotor nerve, in a dense network of nerve fibers. This nucleus is paired, composed of small cells, and divides into two parts - internal and external; some authors distinguish the upper end of the internal part as a special 'anterior median nucleus'. The fibers from the W.-E. n. enter into the composition of the oculomotor nerve, from which they differ in smaller caliber; in the composition of this nerve they reach the orbit, where they separate from it and end in the ciliary ganglion, from which fibers - nn. ciliares - go for the innervation of the smooth muscles of the eye (m. ciliaris and m. sphincter iridis). The function of this nucleus is reduced to the narrowing of the pupil and to the contraction of the m. ciliaris, which participates in the act of accommodation of the eye.