sternothyroid

noun

ster·​no·​thy·​roid ˌstər-nō-ˈthī-ˌrȯid 

: an infrahyoid muscle on each side of the body below the sternohyoid that arises from the sternum and from the cartilage of the first and sometimes of the second ribs, inserts into the thyroid cartilage, and acts to draw the larynx downward by depressing the thyroid cartilage

sternothyroid adjective