Sternothyroid muscle
Musculus sternothyreoideus
Sternothyroid is a broad infrahyoid strap muscle that runs from the back of the manubrium to the thyroid cartilage of the larynx.
At a glance
- English
- Sternothyroid muscle
- Latin (TA2)
- Musculus sternothyreoideus
- System
- Muscle
- Region
- Neck
- Side
- Paired, left and right
About the sternothyroid muscle
Sternothyroid is one of the infrahyoid strap muscles of the anterior neck. It lies deep to sternohyoid and is shorter and wider than that muscle. Low in the neck the two sternothyroids touch each other in the midline, but they move apart as they ascend so that the front of the trachea and larynx shows between them.
It takes origin from the back of the manubrium, below the attachment of sternohyoid, and from the edge of the first costal cartilage. The fibres pass upward over the front of the thyroid gland and end on the oblique line on the outer face of the thyroid cartilage lamina. From that line the thyrohyoid muscle continues upward to the hyoid, so the two read almost as one strap interrupted by the cartilage. A tendinous line may cross the muscle.
Because it reaches the thyroid cartilage rather than the hyoid, its main action is to draw the larynx downward after it has been lifted during swallowing or singing. In doing so it also helps to lower the hyoid indirectly, together with the other infrahyoid muscles. It is supplied by branches of the ansa cervicalis.
Its attachment to the oblique line closes off the upward path for an enlarging thyroid gland. A goitre lying under the muscle therefore grows forwards, backwards or down into the chest, but not upward past the cartilage. In thyroid surgery the muscle is retracted or partly divided to expose the gland, and doubling, absence or extra slips to nearby structures are recorded variations.
Attachments, action and supply
- Origin
- Back of the manubrium below sternohyoid, and the edge of the first costal cartilage.
- Insertion
- Oblique line of the thyroid cartilage, on the outer face of its lamina.
- Action
- Draws the larynx and thyroid cartilage down after swallowing and voice; helps to lower the hyoid indirectly.
- Nerve supply
- Ansa cervicalis (C2 and C3).
- Blood supply
- Superior thyroid artery.
Anthromica
See the sternothyroid muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
