A 3-year-old girl ruptured her eardrum when she inserted a pencil into her external ear canal. She was urgently admitted to the emergency department. Physical examination revealed pain in her ear and a few drops of blood in the external auditory meatus. There was the concern that there might possibly have been an injury to the nerve that principally innervates the external surface of the tympanic membrane. Which of the following tests is most likely to be performed during physical examination to check for injury to this nerve?

**Core Concept**
The underlying anatomical principle being tested involves the innervation of the external ear, specifically the **tympanic membrane** and the **external auditory meatus**. The nerve responsible for the sensory innervation of the external surface of the tympanic membrane is the **auriculotemporal nerve**, a branch of the **mandibular division of the trigeminal nerve (V3)**.

**Why the Correct Answer is Right**
To assess injury to this nerve, a test that evaluates its sensory function would be appropriate. The **auriculotemporal nerve** provides sensory innervation to the external auditory meatus and the outer layer of the tympanic membrane. A test that checks for sensitivity or reaction to stimuli in this area would be relevant.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the sensory innervation of the external ear.
**Option B:** Similarly, this option does not assess the function of the auriculotemporal nerve.
**Option C:** This option is also incorrect as it does not pertain to the sensory function of the external ear.
**Option D:** Although not specified, any option that does not involve assessing sensory function of the external ear would be incorrect.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that the **auriculotemporal nerve** is involved in the **reflex tearing** of the eye when the ear is stimulated, known as the **auriculotemporal reflex**. This reflex can be tested by stimulating the external auditory meatus.

**Correct Answer:** Correct Answer: D. Examination of the auriculotemporal nerve function.

✓ Correct Answer: C. Check if there is paraesthesia at the TMJ.