Posterior Cricoarytenoid
Larynx · Head & Neck
The posterior cricoarytenoid is the single most important intrinsic laryngeal muscle, because it is the only muscle that opens the airway. It arises from the broad posterior surface of the cricoid lamina and its fibres converge upward and laterally to insert on the muscular process of the arytenoid cartilage. Pulling the muscular process backward and medially, it rotates the arytenoid so that the vocal process swings outward, abducting the vocal folds and widening the rima glottidis. It is supplied by the recurrent laryngeal nerve (vagus, CN X). Bilateral loss of this muscle, as in recurrent laryngeal nerve injury, can leave the folds adducted and dangerously narrow the airway.
Origin, Insertion, Action & Nerve
Origin
Posterior surface of the cricoid lamina
Insertion
Muscular process of the arytenoid cartilage
Action
Abducts the vocal folds, opening the rima glottidis (the only abductor of the vocal folds)
Nerve
Recurrent laryngeal nerve (vagus, CN X)
Attachments explained
The Posterior Cricoarytenoid is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Posterior surface of the cricoid lamina
Insertion
Muscular process of the arytenoid cartilage
Action & function
When the Posterior Cricoarytenoid contracts, it produces the following movement: Abducts the vocal folds, opening the rima glottidis (the only abductor of the vocal folds).
As part of the Larynx group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Posterior Cricoarytenoid receives its nerve supply from the Recurrent laryngeal nerve (vagus, CN X).
Because a muscle can only contract when its nerve is intact, injury to the Recurrent laryngeal nerve can weaken or paralyse the Posterior Cricoarytenoid, impairing the movements it normally produces (abducts the vocal folds, opening the rima glottidis (the only abductor of the vocal folds)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Posterior Cricoarytenoid (the OIANS method)
Give the posterior cricoarytenoid top priority as the sole abductor of the vocal folds, the only muscle that opens the rima glottidis. Trace its pull from the back of the cricoid lamina to the muscular process, note that swinging that process back rotates the vocal process outward, and the abduction action becomes a matter of simple leverage.
Contrast it directly with the lateral cricoarytenoid, its antagonist, which closes the same rima glottidis from the front of the cricoid arch. Both share the recurrent laryngeal nerve, so bilateral damage is a clinical emergency: with no opener working, the folds sit closed and the airway is threatened, which is why this one muscle is worth memorising above the rest.
Frequently asked questions
Where is the Posterior Cricoarytenoid located?
The Posterior Cricoarytenoid is a muscle of the Larynx group, located in the Head & Neck.
What is the origin of the Posterior Cricoarytenoid?
Posterior surface of the cricoid lamina
What is the insertion of the Posterior Cricoarytenoid?
Muscular process of the arytenoid cartilage
What movements does the Posterior Cricoarytenoid produce?
Abducts the vocal folds, opening the rima glottidis (the only abductor of the vocal folds)
What nerve supplies the Posterior Cricoarytenoid?
Recurrent laryngeal nerve (vagus, CN X)
Is the Posterior Cricoarytenoid free to study in OIANS?
The Posterior Cricoarytenoid is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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