Horner syndrome results from interruption of the sympathetic supply to the face and eye. The complete triad includes ptosis, miosis, and anhidrosis of the face. The first-order neuron of the oculosympathetic pathway originates from:

• A Hypothalamus (ipsilateral), descending through the brainstem and cervical spinal cord to synapse at C8-T2 (ciliospinal centre of Budge) ✓
• B Edinger-Westphal nucleus in the midbrain
• C Superior cervical ganglion, sending fibres along the internal carotid artery
• D Ciliary ganglion, sending post-ganglionic parasympathetic fibres to the dilator pupillae

Explanation

The oculosympathetic pathway is a three-neuron arc. The first-order (central) neuron originates in the posterolateral hypothalamus and descends ipsilaterally through the brainstem tegmentum and cervical spinal cord to synapse in the ciliospinal centre of Budge (C8–T1). The second-order neuron exits, passes over the pulmonary apex and subclavian artery, and synapses in the superior cervical ganglion. The third-order neuron travels along the internal carotid artery to the orbit. The Edinger-Westphal nucleus supplies parasympathetic fibres (via CN III) to the constrictor pupillae — its damage causes mydriasis, not Horner's.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.