label: Neck Lymph Node Boundary Sublevel IIA
label_lc: neck lymph node boundary sublevel iia
description: "The following anatomical structures define the neck lymph node boundary for sublevel IIA: Superior: skull base; inferior: horizontal plane defined by the inferior border of the hyoid bone; anterior (medial): stylohyoid muscle; posterior (lateral): vertical plane defined by the spinal accessory nerve. (AJCC 8th ed.)"