external abdominal oblique muscle, one of a pair of muscles that are the largest and the most superficial of the five anterolateral muscles of the abdomen. It is a broad, thin four-sided muscle that acts to compress the contents of the abdomen and assists in micturition, defecation, emesis, parturition, and forced expiration. Both sides acting together serve to flex the vertebral column, drawing the pubis toward the xiphoid process. One side alone functions to bend the vertebral column laterally and to rotate it, drawing the shoulder of the same side forward. Also called obliquus externus abdominis. Compare internal abdominal oblique muscle.
