Anatomy study note · Head and neck

Oculomotor nerve

The third cranial nerve (motor). It lifts the upper eyelid, turns the eye up, down and medially, constricts the pupil and accommodates the lens.

Key points

• CN III: all extraocular muscles except superior oblique (IV) and lateral rectus (VI).
• Also levator palpebrae, sphincter pupillae, ciliary muscle (via the ciliary ganglion).
• Palsy: down and out, ptosis, fixed dilated pupil.
• III: somitomeres 1–2.
• Motor nuclei: basal lamina. Sensory nuclei: alar lamina.
• III parasympathetic: ciliary muscle + sphincter pupillae.
• Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.

The full note in the atlas also covers

Course · Branches · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 12, PDF pp. 1585, 1663–1665, 1684
• Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 312, 318, 345; ch. 9, PDF p. 126
• BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 166, 171–172; ch. 21, PDF p. 382

More from the head and neck

• Olfactory nerve
• Omohyoid
• Ophthalmic artery
• Ophthalmic nerve
• Ophthalmic veins
• Optic nerve
• Orbicularis oculi
• Orbicularis oris
• Palate
• Palatine tonsil
• Palatopharyngeus
• Parathyroid glands

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