The ciliary ganglion is one of four parasympathetic ganglia of the head and neck. It receives parasympathetic fibres from the oculomotor nerve.

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

• parasympathetic root (fibres synapse in the ganglion)
  • from the Edinger-Westphal nucleus of the oculomotor nerve (III)
• sympathetic root (fibres pass through the ganglion without synapsing)
  • from the ICA (from the superior cervical ganglion) via the nasociliary nerve (V1)
• sensory root (fibres pass through the ganglion without synapsing)
  • via the small communicating branch of the ciliary ganglion (from nasociliary - V1)

Branches

• ~12 or more branches, termed short ciliary nerves
• each contains elements from all 3 roots (above), and pierce back of sclera around attachment of optic nerve to supply the globe
• the vast marjority of fibres from ganglionic cells supply ciliary body (accommodation); only ~3% supply sphincter pupillae
• note; while both long and short ciliary nerves contain sensory/sympathetic supply to the cornea, iris, & ciliary body; only short ciliary are involved in pupillary constriction & 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