The following are the superior and side views of the larynx. Which letter denotes the abductor of the vocal cords?
Ans: A. A
(Ref: Gray’s 41/e p571, 40/e p585)
The only abductor of the larynx is posterior cricoarytenoid muscle, which is the posterior most muscle. All other muscles are adductors of the vocal cords.
- A: Posterior cricoarytenoid muscle; B: Cricothyroid muscle; C: Lateral cricoarytenoid muscle; D: Oblique & transverse arytenoid muscle
- Only laryngeal muscles, that open (abduct) the glottis.
- They rotate the arytenoid cartilages laterally around an axis that passes through the cricoarytenoid joints, producing separation of the vocal processes and the attached vocal cords.
- They also pull the arytenoids backwards, assisting the cricothyroids to lengthen the vocal cords.
- The most lateral fibres draw the arytenoid cartilages laterally, and so the lima glottidis becomes triangular when the posterior cricoarytenoid muscles contract.
- The posterior cricoarytenoids are active in the production of unvoiced sounds.