A group of four pairs of muscles that are located in the anterior triangle of the neck inferior to the hyoid bone. Include the superficially located omohyoid and sternohyoid muscles and the deeper sternothyroid and thyrohyoid muscles. Innervated by the ansa cervicalis except for the thyrohyoid, which is innervated by the hypoglossal nerve. Primarily depress the hyoid bone, except for the sternothyroid, which depresses the thyroid cartilage.