Anatomy of the vagal nerve

1. Big picture

The vagus nerve, cranial nerve X, is the most clinically important lower cranial nerve because it connects brainstem anatomy with swallowing, voice, airway protection, autonomic control, and visceral sensation.

For the exam, the vagus nerve is usually tested through:

• Hoarseness / dysphonia

• Dysphagia and aspiration

• Palatal weakness and uvula deviation

• Absent or reduced gag/palatal reflex

• Recurrent laryngeal nerve palsy

• Jugular foramen syndromes

• Lateral medullary / Wallenberg syndrome

• Autonomic signs: tachycardia if vagal function is lost, bradycardia with vagal stimulation

The key idea is: CN X = pharynx + larynx + parasympathetic viscera.