Nasopharynx

Abstract

The nasopharynx represents a tubular structure that extends from the skull base and the clivus to the level of the hard palate where the oropharynx begins.Communication takes place via the main nasal cavity. The nasopharynx is a muscular tube lined by mucosa and enveloped by the pharyngobasilar fascia. The Eustachian tubes penetrate the pharyngobasilar fascia to open into the nasopharynx. The function of each Eustachian tube is determined by the tensor veli palatini, the levator veli palatini and the stylopharyngeus muscles.

Waldeyer’s ring is a group of lymphoid tissue associations at the upper end of the pharynx and contains the pharyngeal, palatine and lingual tonsils and surrounding submucosal lymphoid tissue.

The parapharyngeal space (PPS) has a central location, as it is surrounded by all the other deep spaces of the neck. Only a limited number of pathological processes directly arise from the PPS; more commonly this space is infiltrated or displaced by lesions arising elsewhere. The precise localisation of such lesions can significantly limit the differential diagnosis. Anatomically, the PPS is a fat-filled space with irregular borders and has the shape of an inverted pyramid. It extends from the base of the skull to the level of the hyoid bone. The PPS is bounded laterally by the medial wall of the masticator space. The medial pterygoid muscle forms the medial boundary of the masticator space, separating the masticator space from the PPS.