A 17-year-old woman is admitted to the hospital with tonsillitis. A tonsillectomy is performed and the patient complains postoperatively of ear pain. Which of the following nerves was most likely injured during the surgical procedure?

**Core Concept**
The question tests the anatomical relationship between the tonsils and surrounding nerves, specifically the nerves responsible for transmitting sensory information from the ear and surrounding structures.

**Why the Correct Answer is Right**
The tonsils are located in the oropharynx, near the palatine tonsillar fossa. The glossopharyngeal nerve (cranial nerve IX) is responsible for transmitting sensory information from the oropharynx, including the tonsils, as well as the external auditory meatus and the tympanic membrane. The glossopharyngeal nerve is closely associated with the tonsils and can be easily injured during tonsillectomy, leading to referred ear pain.

**Why Each Wrong Option is Incorrect**
**Option A:** The vagus nerve (cranial nerve X) is responsible for transmitting sensory information from the larynx and the pharynx, but it is not directly associated with the tonsils or the external auditory meatus.
**Option B:** The trigeminal nerve (cranial nerve V) is responsible for transmitting sensory information from the face, but it is not associated with the ear or the tonsils.
**Option C:** The facial nerve (cranial nerve VII) is responsible for transmitting sensory information from the face, including the external auditory meatus, but it is not associated with the tonsils.

**Clinical Pearl / High-Yield Fact**
The glossopharyngeal nerve is responsible for the afferent limb of the gag reflex, which can be elicited by stimulating the tonsillar fossa.

**Correct Answer: C. Glossopharyngeal nerve.

✓ Correct Answer: D. Glossopharyngeal