Final answer:
The inner longitudinal layer of pharyngeal muscles contracts during the esophageal phase of deglutition to help move the food bolus towards the stomach. These muscles also work in conjunction with the extrinsic tongue muscles for efficient chewing and formation of the bolus.
Step-by-step explanation:
The inner longitudinal layer of pharyngeal muscles plays a significant role in the process of deglutition, which is commonly known as swallowing.
The contraction of the longitudinal muscle layer of the muscularis during the esophageal phase of deglutition assists in shortening and widening the esophagus to help move the food bolus towards the stomach.
This muscular action is part of a series of coordinated contractions that move the bolus through the oropharynx and laryngopharynx, after which relaxation of the upper esophageal sphincter allows the bolus to enter the esophagus.
In addition to facilitating swallowing, the muscles in the pharynx and those attached to the tongue, such as the palatopharyngeal arch, perform important functions in optimizing the positioning of food for chewing and forming the food into a bolus.
The extrinsic muscles of the tongue, including the palatoglossus, hyoglossus, styloglossus, and genioglossus muscles, all contribute to these digestive functions.