These images are from a CT of the lower abdomen and pelvis. What do you think might be causing the patient's abdominal pain?

This diagram shows the basic idea of a TRAM flap. A lower abdominal incision allows the muscle and overlying fat and skin to be moved into the region of a prior mastectomy to reconstruct a breast with the patient's own tissues. What feature of rectus abdominus makes it a good donor site for such a procedure?