Final answer:
The posterior digastric belly helps raise the hyoid bone and the larynx during swallowing and plays a role in depressing the mandible to open the mouth.
Step-by-step explanation:
The action of the posterior digastric belly is crucial for several functions during the process of eating. This muscle is part of a group of muscles known as the suprahyoid muscles, which include the mylohyoid, stylohyoid, and geniohyoid muscles. Together, they work to raise the hyoid bone, the floor of the mouth, and the larynx during deglutition (swallowing). Specifically, the posterior digastric belly assists in elevating the hyoid bone and the larynx, which allows for the safe passage of food from the mouth to the esophagus. Additionally, when the digastric muscle contracts, it plays a role in depressing the mandible, aiding in mouth opening.