Ciliary Ganglion

Figure 1

What is it?
It is a parasympathetic ganglion of the oculomotor nerve (CNIII) meaning: its preganglionic parasympathetic input is from the oculomotor nerve.

Although sensory and sympathetic fibers pass through it, only the parasympathetic fibers synapse in the ganglion – thus making it a parasympathetic ganglion.

Where is it located?

Simply, in the posterior part of the orbit immediately lateral to the optic nerve.

Fibers?

Parasympathetic fibers: 

• Preganglionic fibers originate in the Edinger Westphal nucleus in the midbrain and are carried by the oculomotor nerve.
• These preganglionic fibers synapse in the ganglion
• Postganglionic fibers pass through short ciliary nerve to:

o   Sphincter pupillae muscle --> constrict pupil (meiosis)

o   Ciliary muscle --> lens accommodation for near vision

Sensory fibers:

• Come from the nasociliary nerve
• Pass through ganglion without synapsing
• Continue along short ciliary nerve as well for:

o   Sensory innervation to eyeball

Sympathetic fibers:

• Come from superior cervical ganglion
• Carried with the sympathetic plexus of the internal carotid artery
• Pass from the plexus to the ganglion
• Pass through the ganglion synapsing
• Continue along short ciliary nerve as well to:

o   Dilator pupillae --> dilate pupil (mydriasis)

Short Ciliary nerve: Therefore the short ciliary nerves carry the postganglionic fibers of the oculomotor nerve as well as the sympathetic and sensory fibers.

Note: The long ciliary nerve is a branch of the nasociliary nerve (which in itself is a branch of the Opthalmic division (V1) of the Trigeminal nerve). It carries sensory fibers to the eyeball and may sometimes carry sympathetic fibers as well (for papillary dilation).

Reference:

Drake, R., Vogl, A., & Mitchell, A. (2010). Chapter 8: Head and neck - orbit. Gray's anatomy for students (2nd ed., pp. 878-902). Philadelphia: Elsevier

Snell, R. (2007). Chapter 18: The eye and the ear. Clinical anatomy by systems (pp. 657-685). Philadelphia: Lippincott Williams & Wilkins.

Figure reference:

1. Done by me