Final answer:
The muscles involved in bolus preparation include suprahyoid and extrinsic tongue muscles for positioning and moving food, as well as pharyngeal constrictor muscles for pushing the bolus into the esophagus.
Step-by-step explanation:
The muscles involved in bolus preparation include the suprahyoid muscles (such as the digastric, stylohyoid, mylohyoid, and geniohyoid), which are responsible for raising the hyoid bone and the larynx during deglutition, in addition to helping press the tongue to the roof of the mouth. The extrinsic muscles of the tongue, namely the palatoglossus, hyoglossus, styloglossus, and genioglossus, position food for optimal chewing, gather it into a bolus, and ensure it is in the correct position for swallowing. Additionally, the pharyngeal constrictor muscles move the bolus toward the esophagus, as the upper esophageal sphincter relaxes to allow the passage of food. Following this phase, a complex series of contractions in the esophagus, including the actions of the circular and longitudinal muscle layers of the muscularis, propel the bolus towards the stomach.