Vocal cords are abducted by: March 2003
**Question:** Vocal cords are abducted by: March 2003
**Core Concept:** The abduction of vocal cords refers to the movement of the vocal cords apart, allowing for better vocalization and speech production. The primary motor nerves responsible for this function are the recurrent laryngeal nerves (RLNs).
**Why the Correct Answer is Right:** The correct answer, RLNs, are part of the sympathetic division of the autonomic nervous system and supply the muscles of the larynx, including the cricothyroid muscle. In March 2003, the RLNs were likely discussed in the context of their role in abducting the vocal cords.
**Why Each Wrong Option is Incorrect:**
A. **Option A (Motor neurons):** Motor neurons are responsible for voluntary muscle contractions, not the involuntary actions of the RLNs.
B. **Option B (Parasympathetic nerves):** Parasympathetic nerves are part of the parasympathetic division of the autonomic nervous system and primarily control involuntary functions, such as salivation and pupil dilation, not vocal cord abduction.
C. **Option C (Sympathetic ganglia):** Sympathetic ganglia are part of the sympathetic nervous system, but they are the initial segment of the RLNs, not the actual abducting nerves themselves.
D. **Option D (Cricothyroid muscle):** Although the cricothyroid muscle is involved in vocal cord abduction, the correct answer focuses on the RLNs as the source of innervation for this muscle.
**Clinical Pearl:** The recurrent laryngeal nerves are essential for understanding the motor control of the larynx and speech production, highlighting the importance of the autonomic nervous system in maintaining respiratory and vocal functions. This concept is crucial for understanding the physiology of the larynx and speech production in medical students and healthcare professionals.
**Correct Answer:** RLNs (Option D)
**Explanation:** The recurrent laryngeal nerves (RLNs) are the correct answer because they are responsible for the movement of the vocal cords, specifically the cricothyroid muscle. The RLNs are part of the autonomic nervous system, which controls involuntary functions in the body.
**Why the Wrong Options are Incorrect:**
A. Motor neurons (Option A) are involved in voluntary muscle contractions but not the involuntary actions of the RLNs.
B. Parasympathetic nerves (Option B) are part of the parasympathetic nervous system, which controls involuntary functions different from the RLNs.
C. Sympathetic ganglia (Option C) are the initial segment of the RLNs, not the actual nerves responsible for vocal cord movement.
**Clinical Relevance:** Understanding the role of the RLNs in vocal cord movement is crucial for physicians, as misdiagnosis or improper treatment can lead to dysphonia (voice disorders) or airway obstruction, which are significant clinical issues in respiratory and otolaryngology specialties.