Involvement of which cranial nerve produces the characteristic triad of ipsilateral Horner syndrome, loss of pain and temperature on the face, and dysphagia/hoarseness in a lateral medullary infarct?

• A CN VII (facial) nucleus and CN VI (abducens) fascicles
• B CN XI (accessory) and CN XII (hypoglossal) nuclei
• C CN IX (glossopharyngeal) and CN X (vagus) nuclei plus descending sympathetic fibres and spinal trigeminal nucleus ✓
• D CN V (trigeminal) motor nucleus and CN VI (abducens) nucleus

Explanation

Wallenberg (lateral medullary) syndrome involves structures in the lateral medulla supplied by PICA: the nucleus ambiguus (CN IX, X motor — causing ipsilateral palatal palsy, hoarseness, dysphagia), the spinal trigeminal nucleus (ipsilateral facial pain/temperature loss), descending sympathetic fibres (ipsilateral Horner syndrome), the vestibular nuclei (vertigo, nausea), and the spinothalamic tract (contralateral body pain/temperature loss). CN VII and VI nuclei are pontine structures and would produce a different clinical picture. CN XII nucleus is in the medial medulla, part of the medial medullary syndrome.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.