Nerve · Head

Long ciliary nerves

Nervi ciliares longi

Two or three fine nerves that leave the nasociliary nerve as it crosses above the optic nerve, then run forward to pierce the white of the eye close to where the optic nerve enters it. From there they travel in the plane between the sclera and the choroid all the way to the front of the eye, supplying the cornea, iris and ciliary body. They are called long because they take this direct route from the parent trunk, whereas the short ciliary nerves relay through the ciliary ganglion first. Alongside their sensory fibres they carry sympathetic fibres to the muscle that widens the pupil — so the same slender threads that report a scratch on the cornea also help open the pupil in the dark.