Abdominal Oblique Muscles

The "external abdominal oblique muscle" lies on the sides and front of the abdomen and is the largest and the most superficial of the three flat muscles in this area. It is broad, thin and irregularly four-sided and occupies the lateral walls of the abdomen, stretching across to the front. Both sides, acting together, flex the vertebral column by drawing the pubis toward the xiphoid process (the smallest of the three parts of the breastbone). One side also bends the vertebral column sideways and rotates it, bringing the shoulder of that side forward. The "internal abdominal oblique muscle" is also irregularly four-sided in form and lies under the external oblique muscle. Both sides, acting together, flex the vertebral column, drawing cartilages down toward the pubis. One side acting alone bends the vertebral column sideways, rotating it to bring the shoulder of the opposite side forward. Both of the abdominal oblique muscles work to compress abdominal contents, assist in the digestive process and in forced expiration.