The neck has so many structures that anatomists have divided it into anterior and posterior triangles. The anterior triangle is further divided into four smaller "subtriangles." Knowing the triangles for their own sake is not as important as knowing their location; you can easily find structures if you know which triangle they occupy.

Figure 8-1
Anterolateral view of the head and neck.

These triangles can be easily visualized by constructing a rectangle with a diagonal line running from top left to bottom right. The left side triangle represents the posterior triangle of the neck, and the right side triangle represents the anterior triangle of the neck. The diagonal of the square is the sternomastoid and therefore serves as a boundary for both triangles (Figure 8-1)