The ciliary ganglion serves as the site of synapse for the parasympathetic nerves innervating the eye.  Because of the many nerves that course through it (not all of them synapse!) and its anatomical location, this structure is of importance in learning the basics of ophthalmology.  According to the Basic and Clinical Science Course, it is located lateral to the ophthalmic artery, situated between optic nerve and lateral rectus muscle, approximately 1 cm (10 mm) anterior to the annulus of Zinn and 1.5-2 cm (15-20 mm) posterior to the globe (1-5).