A patient presents with difficulty chewing and a diminished jaw jerk reflex. Which cranial nerve is most likely affected?

A Oculomotor nerve (CN III)

B Trigeminal nerve (CN V)

C Facial nerve (CN VII)

D Glossopharyngeal nerve (CN IX)

✓ Correct Answer: Option B

The trigeminal nerve (CN V) innervates the muscles of mastication (e.g., masseter, temporalis) and carries both afferent and efferent components of the jaw jerk reflex. Damage would impair chewing and the reflex.

💡 Why is B) the correct answer?

The correct answer to the question "A patient presents with difficulty chewing and a diminished jaw jerk reflex. Which cranial nerve is most likely affected?" is Option B: Trigeminal nerve (CN V).

The other options — A) Oculomotor nerve (CN III), C) Facial nerve (CN VII), D) Glossopharyngeal nerve (CN IX) — are incorrect for this USMLE Exam Prep question. As explained above: The trigeminal nerve (CN V) innervates the muscles of mastication (e.g., masseter, temporalis) and carries both afferent and efferent components of the jaw jerk reflex. Damage would impair chewing an…

📚 About This USMLE Exam Prep Practice Question

This 2-level USMLE Exam Prep question from the Step 1 – Basic Sciences topic is part of BrainForge Quiz's free exam preparation library. Each question includes the correct answer and a detailed explanation to help you understand the underlying concept, not just memorize the answer.

How to use this page: Read the question above, consider all four options (A through D), then check the highlighted correct answer and explanation. For active timed practice, start a free USMLE Exam Prep practice test or use flashcards for spaced repetition review.

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A patient presents with difficulty chewing and a diminished jaw jerk reflex. Which cranial nerve is most likely affected?

✓ Correct Answer: Option B

📚 About This USMLE Exam Prep Practice Question

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