The infrahyoid muscles are a group of four muscles located in the neck, below the hyoid bone. These muscles include the sternohyoid, omohyoid, sternothyroid, and thyrohyoid. They play a crucial role in stabilizing and moving the hyoid bone and larynx during swallowing and speaking. These muscles are innervated primarily by the ansa cervicalis, a loop of nerves in the neck. The infrahyoid muscles help lower the hyoid bone and larynx, facilitating the process of swallowing and contributing to the regulation of airflow during speech.