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Trigeminal nerve - ophthalmic division (CN V1)
Anatomy & Optics
Key Points
- •CN V1 divides into 3 branches: Lacrimal, Frontal, Nasociliary; the nasociliary nerve is the most important for ophthalmology - gives off long ciliary nerves (corneal sensation), short ciliary nerves (via ciliary ganglion), ethmoidal nerves, and infratrochlear nerve
- •The cornea is the most densely innervated tissue in the body (300–600× skin); nerves from the long ciliary nerves enter at the limbus and lose myelin within 1–2 mm to maintain transparency
- •Corneal reflex: afferent CN V1 (nasociliary), efferent CN VII; Hutchinson's sign (nose tip vesicles = external nasal branch of nasociliary) predicts ~76% ocular involvement in HZO
- •The ciliary ganglion has 3 roots: parasympathetic (CN III, synapse here), sensory (nasociliary/V1, passes through), sympathetic (SCG, passes through); gives off 6–10 short ciliary nerves to the globe
- •Neurotrophic keratitis from CN V1 damage → loss of corneal protective reflexes and trophic support → persistent epithelial defect → melting → perforation; treatment: lubricants, tarsorrhaphy, cenegermin (rhNGF)
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17 more sections are included with the Clinical plan.
- Definition
- Epidemiology
- Aetiology and causes
- Pathogenesis
- Classification
- Risk factors and associations