The posterior cricoarytenoid is the most important intrinsic laryngeal muscle because it is the only abductor of the vocal cords, pulling them apart to open the glottis for breathing. It is described as the muscle of life because bilateral paralysis produces complete glottic closure and fatal airway obstruction unless a tracheostomy is performed. Unilateral paralysis is well-compensated; bilateral paralysis is immediately life-threatening.
| Origin | Posterior surface of the cricoid lamina |
|---|---|
| Insertion | Muscular process of the arytenoid cartilage |
| Nerve Supply | Recurrent laryngeal nerve (CN X) |
| Blood Supply | Inferior laryngeal artery |
| Actions |
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As the sole vocal cord abductor it must dilate the glottis with every breath. Its continuous activity during wakefulness makes it one of the most tonically active muscles in the body, and its relaxation during sleep contributes to the airway narrowing of sleep-disordered breathing.
Bilateral RLN palsy from thyroid surgery, malignancy, or neurological disease produces bilateral vocal cord paralysis in the paramedian position with preserved adduction but no abduction, causing life-threatening inspiratory stridor and airway obstruction requiring immediate tracheostomy. Surgical management with posterior cordotomy or lateralisation arytenoidopexy attempts to restore the airway while preserving voice quality.
Not accessible to external palpation. Assessed by laryngoscopy showing arytenoid and cord abduction pattern.
Bilateral PCA denervation from RLN injury producing complete glottic abduction loss and airway obstruction requiring tracheostomy, managed with cordotomy or lateralisation procedures for decannulation.
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