The sternohyoid is the most superficial of the infrahyoid strap muscles, running from the sternum and clavicle to the hyoid bone on the anterior midline neck. It depresses the hyoid after it is elevated during swallowing, working with the other strap muscles to return the larynx to its resting position. The strap muscles as a group are routinely divided and repaired during anterior neck surgery without significant functional consequence.
| Origin | Posterior surface of the manubrium sterni and medial end of the clavicle |
|---|---|
| Insertion | Lower border of the body of the hyoid bone |
| Nerve Supply | Ansa cervicalis (C1, C2, C3) |
| Blood Supply | Superior thyroid artery |
| Actions | Depression of the hyoid bone after swallowing; Assists in fixing the hyoid during tongue movements and speech |
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The infrahyoid muscles including the sternohyoid act as a fixating group that stabilises the hyoid during the tongue movements of speech and eating, providing a stable foundation from which the suprahyoid muscles can elevate the hyoid and larynx during swallowing.
The sternohyoid is transected during anterior cervical spine surgery, thyroidectomy, and laryngeal procedures and reliably heals without functional deficit. Sternohyoid hypertrophy from habitual neck tension can contribute to an asymmetric anterior neck appearance. The muscle is a landmark for identifying the carotid sheath and its contents during anterior neck dissection.
The sternohyoid is palpable as a strap-like muscle on the anterior midline neck just lateral to the thyroid cartilage, becoming firm during swallowing or when the subject attempts to press the chin to the chest against resistance.
Rare acute injury from whiplash or direct trauma producing anterior neck pain with painful swallowing, managed conservatively.
