Sternothyroid

Origin, Insertion, Action & Nerve

Attachments explained

The Sternothyroid 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 Sternothyroid contracts, it produces the following movement: Depresses the larynx (and the thyroid cartilage) after swallowing.

As part of the Neck 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 Sternothyroid receives its nerve supply from the Ansa cervicalis (C1–C3). This nerve carries fibres from spinal segment(s) C1, C3.

Because a muscle can only contract when its nerve is intact, injury to the Ansa cervicalis or to its spinal roots (C1, C3) can weaken or paralyse the Sternothyroid, impairing the movements it normally produces (depresses the larynx (and the thyroid cartilage) after swallowing). This is why knowing the innervation is central to localising nerve lesions in clinical practice.

How to study the Sternothyroid (the OIANS method)

OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Sternothyroid, 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 Sternothyroid 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.

Sternothyroid quick facts

Region

Head & Neck

Group

Neck

Origin

Posterior surface of the manubrium sterni

Insertion

Oblique line of the thyroid cartilage

Action

Depresses the larynx (and the thyroid cartilage) after swallowing

Nerve

Ansa cervicalis (C1–C3)

Spinal roots

C1, C3

Frequently asked questions

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