Familial Nasopharyngeal Carcinoma 6

82 C. K. Ong and V. F. H. ChongabcFig. 8.1. Normal anatomy of the nasopharynx. (a) SagittalT1-weighted MR image shows the nasopharynx (N) with itsroof abutting the sphenoid sinus (S) and more posteriorly,the clivus (arrow). (b) Axial T1-weighted MR image showsthe right lateral pharyngeal recess (long arrow), torus tubarius(t), and eustachian tube opening (short arrow). Thehyperintense fat of the parapharyngeal space (asterisk) lieslaterally. Note asymmetry of the lateral pharyngeal recesses,a common finding. (c) Coronal T1-weighted MR imageshows the right lateral pharyngeal recess (long arrow), torustubarius (t), and eustachian tube opening (short arrow).The hyperintense parapharyngeal fat (asterisk) is again seenlaterallycervical vertebrae (Fig. 8.1). The adenoids occupythe roof of the nasopharynx. These lymphoid tissuesinvolute with age but may persist as tags of tissueinto adulthood.The pharyngobasilar fascia, a tough aponeurosisthat connects the superior constrictor muscle to theskull base, provides the principal framework formaintaining the configuration of the nasopharynx(Dillon et al. 1984). This fascia attaches to the medialplate of the pterygoid process anteriorly and extendsposteriorly to the occipital pharyngeal tuber, beforereflecting medially over the prevertebral muscles.The foramen lacerum (the fibrocartilagous floor inthe anterior aspect of the horizontal carotid canal) iswithin the confines of the pharyngobasilar fascia andis thus part of the nasopharyngeal roof. This foramenpresents a route for nasopharyngeal tumors toaccess the cavernous sinus and intracranial cavity.The eustachian tube and levator veli palatini muscleenter the nasopharynx through a posterolateral defect