Final answer:
The pharynx is divided into three regions: the nasopharynx, involved in breathing and speech; the oropharynx, a passageway for air and food; and the laryngopharynx, which guides ingested materials and air towards the digestive and respiratory systems.
Step-by-step explanation:
The three layers of the pharynx that proceed to the retropharyngeal space are known as the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the uppermost region, connected to the nasal cavities and is primarily involved in breathing and speech.
The oropharynx is flanked by the nasopharynx, oral cavity, and is a passageway for both air and food. The laryngopharynx, situated below the oropharynx and posterior to the larynx, is a pathway for ingested material and air until it diverges into the respiratory and digestive systems at its inferior end. The epithelium lining the oropharynx and laryngopharynx is stratified squamous epithelium.