A 55-year-old woman has hoarseness, dysphagia, diminished gag reflex on the right, and loss of the cough reflex. MRI shows an infarct in the right lateral medulla involving a specific nucleus. Which nucleus is affected?

• A Nucleus solitarius
• B Spinal nucleus of the trigeminal nerve
• C Inferior salivatory nucleus
• D Nucleus ambiguus ✓

Explanation

The nucleus ambiguus gives motor fibres to the striated pharyngeal and laryngeal muscles via the glossopharyngeal and vagus nerves and to the cranial accessory nerve. Its infarction produces ipsilateral palatal paralysis, hoarseness, dysphagia and depressed gag and cough reflexes. The nucleus solitarius is sensory for taste and visceral afferents, and the spinal trigeminal nucleus mediates facial pain and temperature, neither of which matches this purely motor bulbar picture.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.