Young singer at local music theatre complains of vocal difficulties. On examination, she is unable to abduct vocal cords during quiet breathing. Which of the following muscles is most likely to be paralyzed?
Young singer at local music theatre complains of vocal difficulties. On examination, she is unable to abduct vocal cords during quiet breathing. Which of the following muscles is most likely to be paralyzed?
💡 Explanation
## **Core Concept**
The question tests knowledge of laryngeal muscles and their functions, specifically in relation to vocal cord movement. The primary muscle responsible for abducting the vocal cords is the **posterior cricoarytenoid muscle**. This muscle plays a crucial role in opening the glottis by rotating the arytenoid cartilages outward, thereby separating the vocal cords.
## **Why the Correct Answer is Right**
The **posterior cricoarytenoid muscle** is the only muscle that can abduct the vocal cords, making it essential for breathing and voice production. When this muscle is paralyzed, the vocal cords cannot be abducted, leading to difficulties in breathing and phonation. The complaint of vocal difficulties and the inability to abduct the vocal cords during quiet breathing point directly to a problem with this muscle.
## **Why Each Wrong Option is Incorrect**
- **Option A:** The **thyroarytenoid muscle** primarily helps in adducting the vocal cords and adjusting pitch and tension. Its paralysis would not lead to an inability to abduct the vocal cords.
- **Option B:** The **lateral cricoarytenoid muscle** helps in adduction of the vocal cords and in adjusting pitch. It does not play a role in abduction.
- **Option D:** The **cricothyroid muscle** is involved in elongating and tensing the vocal cords, thereby increasing pitch. It does not affect abduction or adduction of the vocal cords.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the **posterior cricoarytenoid muscle** is the most commonly affected muscle in vocal cord paralysis due to its complex innervation by the recurrent laryngeal nerve. Vocal cord paralysis can result from various causes, including trauma, surgery, or neuropathy.