Which of the following laryngeal muscle act as an abductor of vocal cord?
**Core Concept**
The laryngeal muscles play a crucial role in the control of voice production and breathing. The abductor muscles are responsible for the opening of the glottis, allowing for inhalation of air. The primary abductor muscle of the vocal cord is the one that opposes the adductor muscles, which are responsible for the closure of the glottis.
**Why the Correct Answer is Right**
The correct answer is the laryngeal muscle that is innervated by the recurrent laryngeal nerve, which is responsible for the abduction of the vocal cord. This muscle works antagonistically to the posterior cricoarytenoid muscle to open the glottis. When the posterior cricoarytenoid muscle contracts, it rotates the arytenoid cartilages, thereby abducting the vocal cord and allowing for inhalation. The correct muscle also helps to prevent the vocal cord from being drawn into the glottis, thereby maintaining a patent airway.
**Why Each Wrong Option is Incorrect**
**Option A:** The thyroarytenoid muscle is an adductor of the vocal cord, not an abductor. It helps to relax the vocal cord and is involved in the closure of the glottis.
**Option B:** The cricothyroid muscle is responsible for elongating and tensing the vocal cord, but it is not an abductor.
**Option C:** The lateral cricoarytenoid muscle is an adductor of the vocal cord, not an abductor. It helps to rotate the arytenoid cartilages and adduct the vocal cord.
**Clinical Pearl / High-Yield Fact**
The posterior cricoarytenoid muscle is the only muscle to be innervated by the recurrent laryngeal nerve, and it is also the only abductor of the vocal cord. This muscle is essential for maintaining a patent airway during inhalation.
**Correct Answer:** C. Lateral cricoarytenoid