Final answer:
Pharyngeal residue refers to the food that remains in the pharynx post-swallowing. It involves the elevator and constrictor muscles of the pharynx, which are innervated by the glossopharyngeal nerve. Proper muscle contraction and coordination are essential to prevent residues and ensure the safe transfer of a food bolus to the esophagus.
Step-by-step explanation:
Pharyngeal residue often refers to the remnants of food that remain in the pharynx after swallowing. During the pharyngeal phase of swallowing, muscles in the pharynx contract to transport a bolus of food from the mouth to the esophagus. The muscles involved include the elevator muscles which raise and expand the pharynx during swallowing, and the constrictor muscles which contract to push the bolus into the esophagus. The innervation of these muscles largely involves the glossopharyngeal nerve (ninth cranial nerve), which is responsible for the contraction of muscles in the tongue and throat.
The action associated with pharyngeal residue, primarily that of the pharyngeal constrictor muscles, is to move the bolus through the oropharynx and laryngopharynx. If there is residue left behind, it may indicate a dysfunction in the swallowing mechanism, potentially requiring medical assessment or intervention. During swallowing, the uvula and soft palate move upward to close off the nasopharynx, while the laryngeal muscles constrict to protect the airways and prevent aspiration. This coordinated action is controlled by the deglutition center in the medulla oblongata, and the entire process involves a complex interaction of neuromuscular events.