Sternothyroid
Neck · Head & Neck
The sternothyroid is an infrahyoid strap muscle lying deep to the sternohyoid, closer to the larynx. It arises from the posterior surface of the manubrium of the sternum and runs upward to insert on the oblique line of the thyroid cartilage. Rather than acting on the hyoid bone directly, it pulls on the larynx: it depresses the larynx, and with it the thyroid cartilage, after these have been raised during swallowing and phonation. Along with the other strap muscles, it receives its innervation from the ansa cervicalis (C1 to C3).
Origin, Insertion, Action & Nerve
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)
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.
Origin
Posterior surface of the manubrium sterni
Insertion
Oblique line of the thyroid cartilage
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)
Distinguish the sternothyroid from its neighbour by its upper attachment: while the sternohyoid reaches the hyoid, the sternothyroid stops short at the thyroid cartilage. That difference matters, because it means the sternothyroid depresses the larynx itself rather than the hyoid bone. Picture it as the deeper, shorter strap that specifically pulls the voice box back down after it has been lifted.
Bracket its nerve with the rest of the strap muscles: the sternothyroid is supplied by the ansa cervicalis (C1 to C3). It also sets up a natural chain with the thyrohyoid, which continues the line from the thyroid cartilage up to the hyoid, so studying the two in sequence maps the full path from sternum to hyoid across the larynx.
Frequently asked questions
Where is the Sternothyroid located?
The Sternothyroid is a muscle of the Neck group, located in the Head & Neck.
What is the origin of the Sternothyroid?
Posterior surface of the manubrium sterni
What is the insertion of the Sternothyroid?
Oblique line of the thyroid cartilage
What movements does the Sternothyroid produce?
Depresses the larynx (and the thyroid cartilage) after swallowing
What nerve supplies the Sternothyroid?
Ansa cervicalis (C1–C3)
Is the Sternothyroid free to study in OIANS?
The Sternothyroid 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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