Describe the pharynx structures of the respiratory system

The pharynx is part of the respiratory system and the digestive system. It is a portion of the throat that lies behind the mouth and nasal cavity. It is present above the trachea and esophagus. It helps in the passing of food and air. 

The pharynx is the tubular structure that is divided into three parts. They are nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the upper portion of the pharynx, which extends from the skull base to the upper layer of the soft palate. The pharyngeal tonsils are located at the posterior wall of the nasopharynx. It is lined with respiratory epithelium. The auditory tube opens into the nasopharynx at the pharyngeal opening. 

The oropharynx is present behind the oral cavity from the uvula to the hyoid bone. It opens anteriorly into the mouth. The oropharynx's lateral wall consists of palatine tonsils, and the anterior wall consists of the tongue. It consists of a flap-like structure called epiglottis. 

The laryngopharynx is also known as the hypopharynx. It connects the throat to the esophagus. It is present below the epiglottis and lower ends of the laryngopharynx divided into the respiratory and digestive pathways. The laryngopharynx is continuous to the esophagus.