The nucleus ambiguus provides the motor neurons for which cranial nerves, and its lesion (as in Wallenberg syndrome) produces which specific deficit?

• A CN VII and IX; ipsilateral facial weakness and dysgeusia
• B CN X and XII; ipsilateral palatal palsy and tongue deviation
• C CN IX, X, and XII; combined bulbar palsy with fasciculation
• D CN IX, X, and XI (cranial part); unilateral palatal palsy, hoarseness, and dysphagia with nasal regurgitation ✓

Explanation

The nucleus ambiguus in the medullary tegmentum contains lower motor neurons for CN IX (stylopharyngeus), CN X (pharyngeal constrictors, intrinsic laryngeal muscles via recurrent laryngeal nerve), and the cranial part of CN XI (which rejoins CN X). Its unilateral lesion (as in lateral medullary/Wallenberg syndrome from PICA infarct) produces ipsilateral palatal palsy (uvula deviates away, palate falls on same side), hoarseness (vocal cord paresis), and dysphagia with nasal regurgitation. CN XII (hypoglossal) nucleus is in the medial medulla and is separate from nucleus ambiguus.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.