**Question:** Abductor muscle of vocal cord is

A. Cricothyroid
B. Thyroarytenoid
C. Auxiliary laryngeal
D. Risorius

**Core Concept:**
The human voice is produced by the movement and tension of the vocal cords. The cricothyroid muscle is one of the primary muscles responsible for controlling the position and tension of the vocal cords. The cricothyroid muscle is composed of two parts: the superior (cricothyroid) and inferior (thyroarytenoid) parts. The superior part is responsible for abducting (moving apart) the vocal cords, while the inferior part is involved in adducting (bringing together) the vocal cords.

**Why the Correct Answer is Right:**
The correct answer, Abductor muscle of vocal cord is Cricothyroid (A), specifically its superior part. The superior part of the cricothyroid muscle plays a crucial role in abducting the vocal cords, which is essential for clear voice production and maintaining airway patency.

**Why Each Wrong Option is Incorrect:**

A. Thyroarytenoid (B) is incorrect because it is the inferior part of the cricothyroid muscle involved in adducting (bringing together) the vocal cords, not abducting them.
B. Auxiliary laryngeal (C) is not the correct muscle responsible for abducting the vocal cords. It is part of the strap muscles and plays a role in maintaining the position of the larynx.
D. Risorius (D) is not involved in the movement of vocal cords; it is responsible for lifting the angle of the mouth and is part of the facial muscles.

**Clinical Pearl:**
Understanding the correct function of each muscle involved in laryngeal movement is essential for clinical practice, especially in cases related to voice disorders or hoarseness, where identifying the dysfunctional muscle can guide targeted therapy.