The muscles of the abdominal wall are subdivided into a superficial and a deep group.

http://en.wikipedia.org/wiki/Pelvis

Abdomen
The muscles of the abdominal wall are subdivided into a superficial and a deep group.
The superficial group is subdivided into a lateral and a medial group. In the medial superficial group, on both sides of the centre of the abdominal wall (the linea alba), the rectus abdominis stretches from the cartilages of ribs V-VII and the sternum down to the pubic crest.