ABSTRACT
The pharynx is divided into three parts, the nasopharynx, oropharynx, and hypopharynx. The nasopharynx is the upper portion of the pharynx and is separated from the oropharynx by the soft palate. Anatomically, it is the space located behind the nasal cavities and its mucosal lining starts at the posterior choana. The undersurface of the body of the sphenoid bone forms the slanting roof of the nasopharynx that continues inferiorly into the posterior wall, which is formed by the arch of the atlas vertebra and upper part of the body of the axis vertebra. The floor of the nasopharynx is formed by the upper surface of the soft palate, which also separates the nasopharynx from the oropharynx below. The lateral wall of the nasopharynx is formed by the opening of the Eustachian tube superiorly and the upper part of the superior constrictor muscle inferiorly. The orifice of the Eustachian tube is guided by an incomplete cartilaginous ring, which is deficient in the inferolateral aspect. The medial portion of the incomplete cartilaginous ring elevates the overlying mucosa to form the medial crura. The slit-like space situated medial to this crura is the fossa of Rosenmu¨ller; its size and depth varies between individuals.
