The obliquus externus (external oblique) muscle is the outermost muscle covering the side of the abdomen. It is broad, flat, and irregularly quadrilateral.

The obliquus internus (internal oblique) muscle is triangularly shaped and is smaller and thinner than the external oblique muscle that overlies it.

The transversus abdominis muscle is flat and triangular, with its fibers running horizontally. It lies between the internal oblique and the underlying transversalis fascia. The rectus abdominis muscles are long and flat. The muscle is crossed by three tendinous intersections called the linae transversae.

The rectus abdominis is enclosed in a thick sheath formed, as described above, by fibers from each of the three muscles of the lateral abdominal wall.

The pyramidalis muscle is small and triangular. It is located in the lower abdomen in front of the rectus abdominis.