Abductor of vocal cord is?
The abductor of the vocal cord is the posterior cricoarytenoid muscle. That's the one responsible for moving the vocal cords apart. The lateral cricoarytenoid is the adductor, bringing them together. The thyroarytenoid is part of the intrinsic muscles but more involved in shortening and relaxing the vocal cords. The interarytenoid also adducts.
Wait, the options are A to D but not labeled. The correct answer is the posterior cricoarytenoid. Let me structure the core concept around the intrinsic laryngeal muscles. The core concept here is the function of each muscle in vocal cord movement. The posterior cricoarytenoid is the only abductor, so that's the correct answer.
For the wrong options: lateral cricoarytenoid is the adductor, thyroarytenoid is for tension and shortening, interarytenoid for adduction. The clinical pearl might be that posterior cricoarytenoid is the only abductor, and damage here can cause vocal cord paralysis or breathing issues.
I need to make sure each section is concise. The core concept should mention the laryngeal muscles and their functions. The correct answer explanation should detail the posterior cricoarytenoid's role. Each incorrect option should be addressed briefly. The clinical pearl should highlight the importance of this muscle in abduction. Let me check the character count and formatting to stay within the limits.
**Core Concept** The posterior cricoarytenoid muscle is the primary abductor of the vocal cords, while other intrinsic laryngeal muscles mediate adduction, tension, or relaxation. This function is critical for phonation and airway patency.
**Why the Correct Answer is Right** The posterior cricoarytenoid (PCR) abducts the vocal cords by rotating the arytenoid cartilages laterally. This action increases the glottic aperture, facilitating airflow during inspiration. It is innervated by the recurrent laryngeal nerve, and its dysfunction (e.g., in nerve injury) causes vocal cord adduction, leading to stridor or airway obstruction.
**Why Each Wrong Option is Incorrect**
**Option A:** The lateral cricoarytenoid is the *primary adductor* of the vocal cords.
**Option B:** The thyroarytenoid muscle shortens and relaxes the vocal cords, aiding in phonation and pitch modulation.
**Option C:** The interarytenoid muscle adducts the vocal cords, closing the glottis during swallowing or phonation.
**Clinical Pearl / High-Yield Fact** Remember: "PCR = Open the door." The posterior cricoarytenoid is the *only* abductor; unilateral injury may cause paradoxical vocal cord motion, while bilateral injury is life-threatening due to airway compromise.
**Correct Answer: C. Posterior cricoarytenoid muscle**