A 34-year-old swimmer presents to your office with an external ear canal infection (otitis externa). The patient coughs during inspection of the external auditory meatus with a speculum. The cough results from the irritation of which nerve that innervates an area of the external auditory meatus?

**Core Concept**
The question tests the understanding of the **anatomy of the ear** and the **innervation of the external auditory meatus**. The **auriculotemporal nerve**, a branch of the **mandibular division of the trigeminal nerve (V3)**, provides sensory innervation to the external auditory meatus.

**Why the Correct Answer is Right**
The **auriculotemporal nerve** is responsible for the sensory innervation of the external auditory meatus and the temporomandibular joint. When the external auditory meatus is inspected with a speculum, the **auriculotemporal nerve** can be irritated, leading to a cough reflex. This occurs due to the **nerve's connection to the vagus nerve (CN X)**, which provides parasympathetic innervation to various visceral organs, including the lungs.

**Why Each Wrong Option is Incorrect**
**Option A:** The **facial nerve (CN VII)** is primarily responsible for motor innervation of the face and does not play a direct role in the innervation of the external auditory meatus.
**Option B:** The **glossopharyngeal nerve (CN IX)** is involved in the innervation of the pharynx and the tongue, but not the external auditory meatus.
**Option D:** The **vagus nerve (CN X)** is connected to the **auriculotemporal nerve** but is not the primary nerve responsible for the innervation of the external auditory meatus.

**Clinical Pearl / High-Yield Fact**
The **auriculotemporal nerve** is a key structure to remember in the diagnosis and treatment of otitis externa, as its irritation can lead to coughing and other reflexes.

**Correct Answer:** D. Auriculotemporal nerve

✓ Correct Answer: B. Vagus