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

**Core Concept:** The abductor of the vocal cord is a muscle responsible for moving the vocal cords apart, increasing the airway diameter and allowing for clear speech. In humans, the primary abductor of the vocal cords is the **supراسموس العضلات (cricothyroid muscle)**, which is a paired muscle located in the neck, between the thyroid and cricoid cartilages.

**Why the Correct Answer is Right:** The suprahyoid muscles, including the cricothyroid muscle, play a crucial role in maintaining proper vocal cord function. When the cricothyroid muscle contracts, it pulls the vocal cords apart, increasing the airway diameter, which is essential for clear speech production.

**Why Each Wrong Option is Incorrect:**

A. **Cricopharyngeus (CPA)** is a muscle involved in maintaining the upper esophageal sphincter tone and controlling the swallowing reflex. It does not directly abduct the vocal cords.

B. **Cricothyroid (CT)** and **thyroarytenoid (TA)** muscles are crucial for vocal cord movement, but they are not the abductor muscles. The cricothyroid muscle is the correct answer as it is directly responsible for vocal cord abduction.

C. **Arytenoid (AR)** muscles are involved in vocal cord movement, but they are not the primary abductor muscles. The cricothyroid muscle is the correct answer for abducting the vocal cords.

D. **Posterior cricoarytenoid (PCA)** is involved in vocal cord movement, but it is not the abductor muscle. The cricothyroid muscle is the correct answer for vocal cord abduction.

**Clinical Pearl:** Understanding the correct muscle responsible for vocal cord abduction can help in diagnosing and treating conditions related to altered vocal cord movement, such as **stridor** (difficulty in breathing due to airway obstruction) or **laryngospasm** (involuntary tightening of the vocal cords). In such cases, assessing the function of the cricothyroid muscle may be crucial in determining the cause and devising an appropriate treatment plan.

**Correct Answer:** Cricothyroid (CT) muscle