Thyroarytenoid (Thyroepiglottic Part)

Origin, Insertion, Action & Nerve

Attachments explained

The Thyroarytenoid (Thyroepiglottic 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.

Action & function

When the Thyroarytenoid (Thyroepiglottic Part) contracts, it produces the following movement: Widens the laryngeal inlet (vestibule).

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 (Thyroepiglottic 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 (Thyroepiglottic Part), impairing the movements it normally produces (widens the laryngeal inlet (vestibule)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

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

Learn the thyroepiglottic part as the slip of thyroarytenoid that reaches all the way up to the epiglottis and aryepiglottic fold. Because its pull is directed toward the front of the inlet, it widens the vestibule, the opposite of the sphincteric muscles behind it, so read its name (thyroid to epiglottis) as a map of both origin and action.

Set it against the aryepiglottic muscle for a tidy opener-versus-closer pair on the same fold: the aryepiglottic muscle narrows the inlet while the thyroepiglottic part widens it. Both run on the recurrent laryngeal nerve, so contrasting their directions of pull is the efficient way to remember which one opens and which one shuts the aditus.

Frequently asked questions

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