Short ciliary nerves
Postganglionic · M3 ACh
Six to ten nerves from the ciliary ganglion pierce the sclera around the optic nerve and run forward in the suprachoroidal space to the ciliary muscle and sphincter pupillae. They are the efferent limb of the pupillary light reflex and of accommodation.
Traced from the start
Detail
- Light reflex efferent
- Pretectal nucleus → both Edinger–Westphal nuclei → CN III → ciliary ganglion → short ciliary nerves → sphincter pupillae
- Near response
- Ciliary muscle contraction relaxes the zonule so the lens thickens; accompanied by convergence and miosis
- Passengers
- Also carry sympathetic fibres to dilator pupillae and sensory fibres from the cornea and iris
When it goes wrong
Neurosyphilis (or diabetes) damaging the pretectal light-reflex pathway while sparing the near pathway
Argyll Robertson pupils: small irregular pupils that accommodate but do not react to light, bilaterally
Topical antimuscarinic (tropicamide, cyclopentolate, atropine) or systemic anticholinergic load
Mydriasis with cycloplegia (blurred near vision); can precipitate acute angle-closure glaucoma in a shallow anterior chamber — treated with pilocarpine (M3 agonist)
Practise this structure
1 question in the bank tagged Reflexes.