Thyroarytenoid (External Part)

Larynx · Head & Neck

Thyroarytenoid (External Part) belongs to the Larynx group of the Head & Neck. It arises from Inner surface of the thyroid lamina and attaches to Muscular process and lateral surface of the arytenoid cartilage. It is responsible for several movements: Shortens and relaxes the vocal folds; adducts and aids closure of the rima glottidis. Innervation is provided by the Recurrent laryngeal nerve (vagus, CN X).

Origin, Insertion, Action & Nerve

Origin

Inner surface of the thyroid lamina

Insertion

Muscular process and lateral surface of the arytenoid cartilage

Action

Shortens and relaxes the vocal folds; adducts and aids closure of the rima glottidis

Nerve

Recurrent laryngeal nerve (vagus, CN X)

Attachments explained

The Thyroarytenoid (External Part) 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

Inner surface of the thyroid lamina

Insertion

Muscular process and lateral surface of the arytenoid cartilage

Action & function

When the Thyroarytenoid (External Part) contracts, it produces the following movements: Shortens and relaxes the vocal folds; adducts and aids closure of the rima glottidis.

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 Thyroarytenoid (External Part) 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 Thyroarytenoid (External Part), impairing the movements it normally produces (shortens and relaxes the vocal folds). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Thyroarytenoid (External Part) (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Thyroarytenoid (External Part), 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 Thyroarytenoid (External Part) 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.