Which muscle of larynx is supplied by external laryngeal nerve?
**Core Concept**
The question tests knowledge of the **laryngeal innervation**, specifically the supply of the external laryngeal nerve, a branch of the **superior laryngeal nerve**. This nerve is responsible for the motor supply to one of the intrinsic muscles of the larynx. The **external laryngeal nerve** is a crucial component of the **vagus nerve** (cranial nerve X) pathway.
**Why the Correct Answer is Right**
The **cricothyroid muscle** is the only intrinsic muscle of the larynx that is innervated by the **external laryngeal nerve**. This muscle is involved in **pitch regulation** by altering the tension of the vocal cords. The external laryngeal nerve's specific role in supplying this muscle highlights the intricate control over voice modulation.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not specified, but typically, other muscles are innervated by the recurrent laryngeal nerve.
**Option B:** Incorrect as it's not provided, but usually, this would refer to a muscle not supplied by the external laryngeal nerve.
**Option C:** Incorrect, as this choice is not given, but it would likely refer to another laryngeal muscle with different innervation.
**Option D:** Similarly, incorrect due to lack of specification, but it would be a muscle not innervated by the external laryngeal nerve.
**Clinical Pearl / High-Yield Fact**
Remember, the **external laryngeal nerve** supplies the **cricothyroid muscle**, which is key for **voice pitch control**. This is a high-yield fact for exams, as it's a specific and frequently tested piece of knowledge.
**Correct Answer:** Correct Answer: A. Cricothyroid muscle.