A flap is defined as the movement of adjacent skin and subcutaneous tissue with its vascular supply intact. Flaps are classified according to location, blood supply, and movement. This atlas will focus on flaps that arise from adjacent or near adjacent tissue. These flaps derive their blood supply either from a random pattern or an axial pattern (based on a named artery).

Before performing flap surgery, a thorough understanding of flap nomenclature, principles, and dynamics is required.

1. The primary defect is the original wound to be closed.

2. The secondary defect is the wound created by the movement of flap in order to close the primary defect.

3. The primary motion of the flap is the motion or stress placed on it to close the primary defect.

4. The secondary motion is the motion or stress placed on the tissue surrounding the primary defect by the flap.

Therefore, there is a combination of primary and secondary wounds and primary and secondary motions for every flap design and execution. Understanding the direction of the resulting vector forces is critical.

A classic description of flaps is based on their movement: advancement, rotation, and transposition. Advancement flaps are the simplest of the flaps to conceptualize and entail the movement of the adjacent tissue along a single vector.