Final answer:
The sternothyroid and sternohyoid muscles both function to depress, or move inferiorly, their associated anatomical structures, which are the thyroid cartilage and the hyoid bone, respectively.
Step-by-step explanation:
Muscle Functions of the Anterior Neck
The sternothyroid and sternohyoid muscles are integral components of the anterior neck's muscular structure. These muscles are responsible for coordinating movements that are crucial for swallowing and speech. The sternohyoid muscle depresses the hyoid bone, while the sternothyroid muscle depresses the thyroid cartilage of the larynx. It is through the depression of these structures that the pitch of the voice is modulated and the larynx's position is adjusted during the act of swallowing. These muscles play an important role specifically during phonation and deglutition, contributing to the necessary flexibility and control required for these complex actions.
In summary, the action of these muscles relative to their associated structures, the hyoid bone and the thyroid cartilage, is to depress or move them inferiorly. This movement is intrinsic to the function they serve within the context of the infrahyoid muscles, which ensure the stability and appropriate movement of the larynx and hyoid for various physiological functions, particularly those related to the vocal apparatus and upper respiratory tract.