The Ciliary Ganglion

Abstract

The ciliary ganglion is a small ganglion, up to 2 mm in its anteroposterior diameter in man, situated behind the eyeball, lateral to the optic nerve. It receives nerves (its roots) from the aculomotor nerve (radix brevis, generally from the branch to the inferior oblique muscle), and sends nerves (the short ciliary nerves) to the eyeball. In man and a few other species it also contains sensory fibres from the trigeminal nerve (radix longa, from the naso-ciliary nerve) and sympathetic post-ganglionic fibres (radices sympathicae) from the superior cervical ganglion (via the internal carotid plexus); both these orders of fibres pass through the ganglion without interruption. Sensory and sympathetic fibres are absent in the ciliary ganglion of the cat (Whitteridge, 1937; Skok, 1973). In the small rodents the ganglion is composed of microscopic clusters of neurons in the proximity of the optic nerve (Malmfors & Nilsson, 1966 [rat]; Watanabe, 1972 [guinea-pig]).