The sternothyroid muscle, also called the sternothyroideus, is in the neck area. The muscle goes from the sternum, or breastbone, to the edge of the thyroid cartilage. It starts in the manubrium sterni, the uppermost part of the breastbone, and inserts into the lamina, or thin layers, of thyroid cartilage, which is located inferior to (behind) the hyoid. It works to depress the larynx, or voice box, which helps create sound.

The sternothyroid muscle is shorter and wider than the sternohyoid muscle. The sternothyroid muscle lies underneath the sternohyoid muscle. Nerves from the upper cervical nerve travel through the cervical ansa, or cervical loop, and supply the sternothyroid muscle.

The main function of the sternothyroid is to depress the larynx. This is important for mastication, or chewing, as well as swallowing. This raising and lowering of the larynx can also affect vocal range, the ability to control pitch, and volume.

Trauma or injury to this muscle can impact both the ability to vocalize and to consume food.