What is the structure circled in purple below? Be very specific.C contains she letuifude and eintin contain ieratinind ifratifed iguimoons poithefium contars uneceh munde and elastin 41 TpoenPart 1. From what structure (A, B, or C) below would you find the SA node? Part 2. What is the name of the structure identified as "B" below? Part 3. Structure " C " makes up a wall of what chamber of the heart?.