Nerve · Head

Short ciliary nerves

Nervi ciliares breves

A bundle of six to ten fine nerves that leave the front of the ciliary ganglion — a relay station the size of a pinhead sitting behind the eyeball — and run forward to pierce the sclera around the optic nerve, supplying the iris, ciliary body and cornea. They are where three systems meet in one bundle: parasympathetic fibres that have relayed in the ganglion (arriving from the oculomotor nerve) to narrow the pupil and focus the lens, sensory fibres passing straight through from the nasociliary nerve, and sympathetic fibres from the carotid plexus. That mixture is exactly why they cannot be assigned to a single parent nerve. They are the outgoing arm of the reflex that shrinks your pupil when a light is shone at it.