Familial Nasopharyngeal Carcinoma 6

254 W. I. Weimanagement of recurrent NPC in the nasopharynx orthe neck, the first section of the chapter is devoted todescribe the anatomy of the nasopharynx and neckfrom a surgical perspective.20.2Surgical Anatomy20.2.1Surgical Anatomy of the NasopharynxThe pharynx is separated arbitrarily into three partsand the upper one-third is defined as the nasopharynx.This is the region lying behind the nasal cavities andabove the soft palate. The body of the sphenoid boneand the anterior wall of the sphenoid sinus form theslanting roof of the nasopharynx. The roof extendsdownward to merge with the posterior wall that isformed by the clivus, which in turn is connected byligaments to the arch of the atlas and then the upperpart of body of the axis vertebra. The anterior part ofthe floor of the nasopharynx is formed by the superiorsurface of the soft palate and the posterior part opensinferiorly into the oropharynx at the level of the softpalate (Fig. 20.1). The superior constrictor muscle withthe opening of the Eustachian tube or the auditorytympanic tube forms the lateral wall. The medial portionof Eustachian tube is cartilaginous and situatedbetween the skull base and upper edge of the superiorconstrictor muscle. The cartilage that surrounds theorifice of this tube is an incomplete ring, deficient inthe inferolateral portion. The levator veli palatini muscle,attached to the lower edge of this cartilaginous ring,controls the patency of the aperture. The medial portionof the cartilage elevates the mucosa in thenasopharynx to form the medial crura. The slit-likerecess located medial to the crura is the fossa ofRosenmüller, and its size and depth varies betweenindividuals (Fig. 20.2); early nasopharyngeal carcinoma(NPC) is frequently found in this fossa. The anterioraspect of the nasopharynx is the posterior choanaethat opens into the nasal cavity. The posterior part ofthe nasal septum is the vomer, which is attached to theanterior wall of the sphenoid and divides the nasopharynxincompletely into the right and left portions. Lyingfurther laterally on the anterior aspect are the pterygoidplates with attachment of the pterygoid muscles,and in front of these is the maxillary sinus (Fig. 20.2).SCSMPFBACSpACSFig. 20.1. MRI sagittal view of the nasopharynx showingthe roof which is formed by the sphenoid sinus (S) and theclivus (C) with continues onto the Atlas vertebra (A) formingthe posterior wall. The anterior part of the inferior wallis formed by the soft palate (Sp) and the posterior aspectcontinues into the oropharynx (arrow)Fig. 20.2. Schematic CT showing the lateral boundariesof the nasopharynx. C internal carotid artery; F fossa ofRosenmuller; MP medial pterygoid muscle; S styloid process.The black line is the imaginary line joining the medialpterygoid plate to the styloid process. The space in front ofthe line is the prestyloid space (A) and behind the poststyloidspace (B). The Red line is the pharyngobasilar fascia whichjoins with the fascia of the opposite side to form the medianraphe. This fascia together with the prevertebral fascia (Blueline) encloses the retropharyngeal space