**Question:** Which of the following muscle is not supplied by recurrent laryngeal nerve -

A. Laryngeus Communicans
B. Laryngeus Depressor
C. Laryngeus Pullus
D. Laryngeus Pullus and Laryngeus Depressor combined

**Core Concept:** Recurrent Laryngeal Nerve (RLN)

The recurrent laryngeal nerve is a branch of the brachial plexus, which supplies motor innervation to the muscles of the larynx. The primary muscles supplied by the RLN are:

1. Laryngeus Pullus: This muscle is responsible for elevating the vocal cords, which is essential for phonation.
2. Laryngeus Depressor: This muscle is responsible for lowering the vocal cords, which is crucial for protection of the airway and closure of the glottis during swallowing.
3. Laryngeus Communicans: This muscle is responsible for the generation of glottic closure during swallowing, which is also important for preventing food and liquids from entering the airway.
4. Laryngeus Pullus and Laryngeus Depressor combined: This option includes both muscles, which are essential for proper functioning of the larynx.

**Why the Correct Answer is Right:**

Option D (Laryngeus Pullus and Laryngeus Depressor combined) is not correct because both of these muscles are vital for laryngeal functions, as explained above. The RLN supplies both of them and their combined function is crucial for maintaining airway protection, phonation, and glottis closure during swallowing.

**Why Each Wrong Option is Incorrect:**

Option A (Laryngeus Communicans) is incorrect because this muscle is responsible for preventing food and liquids from entering the airway during swallowing, not phonation or airway protection.

Option B (Laryngeus Depressor) is incorrect because although this muscle plays a role in airway protection and glottis closure, it is not the only muscle functioning in these processes.

Option C (Laryngeus Pullus) is incorrect because while this muscle is essential for phonation, it also contributes to airway protection and glottis closure during swallowing.

**Clinical Pearls:**

Understanding the functions of the RLN and its target muscles is crucial in clinical practice, as misdiagnosis or mismanagement of laryngeal disorders can lead to serious complications, such as respiratory distress and airway obstruction. A thorough physical examination of the larynx in patients with respiratory symptoms or voice disorders is essential for accurate diagnosis and treatment planning.