Familial Nasopharyngeal Carcinoma 6

218 J. J. Lu, V. Grégoire, and S. LinTable 17.2. Anatomical structures defining the boundaries of the neck levels and sub-levelsLevelBoundarySuperior Interior Anterior (Medial) Posterior (Lateral)IA Symphysis of mandible Body of hyoid Anterior bally of contralateraldigastric muscleIB Body of mandible Posterior belly of muscle Anterior belly of digastricmuscleAnterior belly of jpsilateraldigastric musciaStylohyoid muscleIIA Skull base Horizontal plane definedby the inferior body of thehyoid boneIIB Skull base Horizontal plane definedby the inferior body of thehyoid boneStylohyoid muscleVertical plane defined by thespinal accessory nerveVertical plane defined bythe spinal accessory nerveLateral border of the stemodeidomastoidmuscleIIIHorizontal plane definedby inferior body of hyoidHorizontal plane definedby the inferior border ofthe pricoid cartilageLateral border of the sternohyoidmuscleLateral border of thestemocleidomastoid ofsensory branches of cervicalplexusIVHorizontal plane definedby the inferior border ofthe cricoid cartilageClavicleLateral border of the stemohyoidmuscleLateral border of thestemocleidomastoid orsensory branches of cervicalplexusVAApex of the convergenceof the sternocleidomastoidand trapeziusmusclesHorizontal plane definedby the lower border of thecricoid cartilagePosterior border of the sternoclaidomastoidmuscle orsansory branches of cervicalplexusAnterior border of thetrapexius muscleVBHorizontal plane definedby the lower border of thecricoid cartilageClaviclePosterior border of thestemocleidomastoid muscleor sansory branches of cervicalplexusAnterior border of thetrapezius muscleVI Hyoid bone Suprasternal Common carolid artery Common carolid alterypositive neck lymph adenopathy, Grégoire et al.(2006) addressed these nodal regions.17.2.2.1Retropharyngeal Lymph NodesRetropharyngeal lymph nodes (RLNs) lie within theretropharyngeal space, which is bounded anteriorly bythe pharyngeal constrictor muscles and posteriorly bythe prevertebral fascia and extends cranially from thebase of the skull to the level of C3 caudally (Rouvière1948). Retropharyngeal nodes can be divided intomedial and lateral groups according to their anatomicalpositions. The medial group lies in or near the midline,and consists of 1–2 lymph nodes, and is usuallynot visible on image studies in physiological condition.The lateral group of retropharyngeal nodes lies medialto the carotid artery, and can be found at any levelwithin the retropharyngeal space (i.e., skull of base tothe level of C3). The most superior lymph node of thelateral group is called the lymph node of Rouvière.