Chapter 1 Neck Anatomy, Imaging-Based Level Nodal Classification and Impact of Primary Tumor Site on Patterns of Nodal Metastasis

The anatomy of the neck is complex, with many critical structures crowded together in a relatively small cross-sectional area. Many structures in the neck also have similar soft tissue density or signal that further complicates interpretation for the radiologist, who relies on tissue differences to create contrast resolution and distinguish structures. Head and neck cancer incidence exceeds 550,000 cases per year worldwide, with diagnosis, treatment, and prognosis relying highly on a thorough knowledge of this compact space. This article focuses on reviewing head and neck anatomy with special attention to nodal anatomy and on discussing the expected patterns of nodal spread in head and neck cancers.