All of the following are supplied by recurrent laryngeal nerve except: (Repeat)
**Core Concept**
The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve that supplies the larynx, playing a crucial role in vocal cord movement and speech production. It is named "recurrent" because it loops back to the larynx from its initial descent.
**Why the Correct Answer is Right**
The RLN primarily supplies the intrinsic muscles of the larynx, including the posterior cricoarytenoid, lateral cricoarytenoid, interarytenoid, thyroarytenoid, and cricothyroid muscles. However, the cricopharyngeus muscle, which is involved in the initiation of swallowing, is actually supplied by the inferior pharyngeal constrictor nerve, a branch of the vagus nerve that arises from the pharyngeal plexus, not the RLN.
**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because the posterior cricoarytenoid muscle, which is responsible for abduction of the vocal cords, is indeed supplied by the RLN.
* **Option B:** Incorrect because the thyroarytenoid muscle, which is involved in vocal cord closure and tension, is also supplied by the RLN.
* **Option C:** Incorrect because the cricothyroid muscle, which adjusts the tension of the vocal cords, is supplied by the RLN.
* **Option D:** Incorrect because the cricopharyngeus muscle, which is responsible for initiating swallowing, is actually supplied by the inferior pharyngeal constrictor nerve, not the RLN.
**Clinical Pearl / High-Yield Fact**
The RLN is a critical nerve for voice production, and its injury can lead to vocal cord paralysis, affecting speech and swallowing. During thyroid surgery, care must be taken to avoid damaging the RLN, which can be identified by its characteristic pulsation with each heartbeat.
**Correct Answer: D. The cricopharyngeus muscle is supplied by the inferior pharyngeal constrictor nerve, not the recurrent laryngeal nerve.**