Ciliary ganglion is a parasympathetic ganglion, situated in the posterior part of the orbit. It is about the size of a pinhead (1-2 mm).
Types of nerve fibers in ciliary ganglion:
Anatomically, three types of nerve fibers run through the ciliary ganglion; parasympathetic fibers, sympathetic fibers and sensory fibers. However, only the parasympathetic fibers form synapses in the ganglion. The other two types run through it uninterrupted. Thus ciliary ganglion is effectively a parasympathetic ganglion.
Preganglionic and postganglionic fibers:
The preganglionic parasympathetic fibers for the ciliary ganglion arise from the Edinger-Westphal nucleus. These fibers travel along the oculomotor nerve and pass to the ganglion via the nerve to the inferior oblique muscle.
The postganglionic parasympathetic fibers leave the ganglion in the short ciliary nerves. These nerves enter the back of the eye ball and innervate the sphincter pupillae and ciliary muscle.