The ciliary ganglion is one of four parasympathetic ganglia of the head and neck. It receives preganglionic parasympathetic fibres from the Edinger-Westphal nucleus via the oculomotor nerve. It supplies the eye via short ciliary nerves not only with parasympathetic fibres, but also with sensory and sympathetic fibres that pass through the ganglion. 

Gross anatomy

• smallest of the ganglia (2 mm in size)

• located posterolaterally in the intraconal space of the orbit (towards the orbital apex) between the optic nerve and the lateral rectus muscle

• just lateral to the ophthalmic artery as it crosses the optic nerve from lateral to medial

Roots

Although the ciliary ganglion has parasympathetic, sensory and sympathetic roots, only the parasympathetic ones synapse within the ganglion. 

• parasympathetic root

  • from the Edinger-Westphal nucleus of the oculomotor nerve (III)

  • fibres synapse in the ganglion

• sympathetic root

  • from the ICA (from the superior cervical ganglion) via the nasociliary nerve, a branch of the trigeminal nerve

  • fibres pass through the ganglion without synapsing

• sensory root 

  • via the small communicating branch of the ciliary ganglion (from the nasociliary nerve, a branch of the trigeminal nerve)

  • fibres pass through the ganglion without synapsing

Branches

• short ciliary nerves 

  • ~12 or more branches, termed 

  • each contains elements from all 3 roots (above), and pierce the back of the sclera around the attachment of the optic nerve to supply the globe

  • the vast majority of fibres from ganglionic cells supply the ciliary body (accommodation); only ~3% supply sphincter pupillae

Note: while both long ciliary nerves (branches of the nasociliary nerve) and short ciliary nerves contain sensory/sympathetic supply to the cornea, iris, and ciliary body, only the short ciliary nerves are involved in pupillary constriction and accommodation.

Related pathology

• pathology of the ciliary ganglion can produce a tonic pupil, where the pupil does not react to light and slowly accommodates

• Adie syndrome: when a non-reactive, slowly accomodating pupil is associated with absent deep tendon reflexes and diaphoresis