Posterior Cricoarytenoid

Larynx · Head & Neck

The Posterior Cricoarytenoid is a Head & Neck muscle within the Larynx group. It arises from Posterior surface of the cricoid lamina and attaches to Muscular process of the arytenoid cartilage. When it contracts, it abducts the vocal folds, opening the rima glottidis (the only abductor of the vocal folds). It is innervated by the Recurrent laryngeal nerve (vagus, CN X).

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)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Posterior Cricoarytenoid, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.

Most students remember the Posterior Cricoarytenoid fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.