Final answer:
The pharynx and esophagus work together during swallowing. The pharynx, lined with a mucous membrane, contracts to push the food bolus into the esophagus, which then directs it to the stomach through coordinated muscle contractions and sphincter control.
Step-by-step explanation:
The anatomy of the pharynx and esophagus is central to the process of swallowing, or deglutition. The pharynx is a muscular passage that starts from the nostrils and runs to the entrance of the esophagus and the larynx. Histologically, it features a mucosa with a stratified squamous epithelium and mucus-producing glands. During swallowing, elevator skeletal muscles of the pharynx rise, expanding the region to receive the food bolus. Following this, the pharynx constrictor muscles force the bolus into the esophagus, beginning peristalsis.
The esophagus, a muscular tube of roughly 25.4 cm, connects the pharynx to the stomach. Swallowing invokes a sequence of reflex actions where the soft palate and uvula block the nasopharynx, and the larynx is pulled up while the epiglottis closes over the glottis, steering the bolus into the esophagus and preventing aspiration into the trachea. The esophagus features upper and lower sphincters that regulate the movement of food to the stomach, while its lining secretes mucus for a smoother passage of the bolus.