The short ciliary nerves are nerves of the orbit around the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

. They are branches of the

ciliary ganglion The ciliary ganglion is a bundle of nerve parasympathetic ganglion located just behind the eye in the posterior orbit. It is 1–2 mm in diameter and in humans contains approximately 2,500 neurons. The ganglion contains postganglionic parasympat ...

. They supply

parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part o ...

and sympathetic nerve fibers to the

ciliary muscle The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscleSchachar, Ronald A. (2012). "Anatomy and Physiology." (Chapter 4) . in the eye's middle layer, uvea (vascular layer). It controls accommodation for viewing ob ...

, iris, and

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

. Damage to the short ciliary nerve may result in loss of the

pupillary light reflex The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity ( luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, the ...

, or

mydriasis Mydriasis is the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of certain types of drugs. Normally, a ...

Structure

The short ciliary nerves are branches of the

. They arise from the forepart of the

ganglion A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympath ...

in two bundles connected with its superior and inferior angles. The lower bundle is the larger than the upper bundle. These split into between 6 and 10 filaments. They run forward with the ciliary arteries in a wavy course. One bundle is set above the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

, while the other bundle is set below it. They are accompanied by the long ciliary nerves from the nasociliary. They pierce the

sclera The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and s ...

at the back part of the bulb of the eye, pass forward in delicate grooves on the inner surface of the sclera, and are distributed to the

, iris, and

Function

The short ciliary nerves contain both

and sympathetic nerve fibers. The parasympathetic fibers arise from the Edinger-Westphal nucleus and synapse in the ciliary ganglion via the

oculomotor nerve The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements o ...

, the postganglionic parasympathetics leave the ciliary ganglion in the short ciliary nerve and supply the

ciliary body The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The aqueous humor is produced in the non-pigmented portion of the ciliar ...

and iris. The sympathetic fibers are provided by the

superior cervical ganglion The superior cervical ganglion (SCG) is part of the autonomic nervous system (ANS); more specifically, it is part of the sympathetic nervous system, a division of the ANS most commonly associated with the fight or flight response. The ANS is co ...

, and reach the ganglion either as branches of the nasociliary nerve or directly from the extension of the plexus on the ophthalmic artery (sympathetic branch to ciliary ganglion). The sympathetics are non-specific and provide vasoconstriction of the globe.

Clinical significance

Damage to the short ciliary nerve may result in loss of the

, or

Additional images

File:Horner's Syndrome and Autonomic innervation of the eye.svg, Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of lesion in a Horner's syndrome. File:Gray840.png, Sympathetic connections of the ciliary and superior cervical ganglia. File:Ciliary ganglion pathways.png, Pathways in the Ciliary Ganglion.

References

External links