A patient presents with hoarseness of voice. Which nerve is most likely affected?

Correct answer: B. Recurrent laryngeal nerve

• A. INCORRECT. While the recurrent laryngeal nerve is a branch of the vagus nerve, hoarseness specifically points to the recurrent laryngeal nerve (not the vagus trunk itself). Lesions of the vagus trunk cause more diffuse symptoms including dysphagia, loss of gag reflex, and autonomic dysfunction in addition to hoarseness.
• B. CORRECT. The recurrent laryngeal nerve (a branch of CN X) provides motor innervation to all intrinsic laryngeal muscles EXCEPT the cricothyroid. Damage to the recurrent laryngeal nerve results in ipsilateral vocal cord paralysis, causing hoarseness (dysphonia), breathy voice, and potential aspiration. Common causes include thyroid surgery, thyroid cancer, lung apex tumors, and aortic arch aneurysm.
• C. INCORRECT. The external branch of the superior laryngeal nerve innervates the cricothyroid muscle (pitch control). Its damage causes inability to change voice pitch (difficulty reaching high notes) rather than classic hoarseness.
• D. INCORRECT. The glossopharyngeal nerve (CN IX) provides sensory innervation to the posterior tongue and pharynx, and motor supply to the stylopharyngeus. It does not innervate the laryngeal muscles and its damage does not cause hoarseness.