Final answer:
The omohyoid muscle, working in tandem with the thyrohyoid muscle, depresses the hyoid bone and controls the position of the larynx, crucial for swallowing and speech.
Step-by-step explanation:
The omohyoid muscle is the one you're asking about. It is essentially one continuous muscle with the thyrohyoid muscle due to its synergistic actions on the hyoid bone and larynx. While the thyrohyoid elevates the larynx's thyroid cartilage, the omohyoid muscle depresses the hyoid bone along with the sternohyoid muscle. These muscles are part of the infrahyoid muscles which generally depress the hyoid bone to control the position of the larynx and are crucial for swallowing and speech. The geniohyoid muscle also plays a role in this movement by depressing the mandible as well as raising and pulling the hyoid bone anteriorly.