The rectus abdominis muscles should meet in the midline at the linea alba. Superior to the umbilicus, some people have a congenital defect that results in a wider gap between them. As a result, when a patient flexes the abdominal muscles as when doing a sit-up, the rectus muscles spread apart (divaricate). The divarication is made more obvious when the patient lifts their head or legs off the bed when supine. Compare epigastric hernia.
Divarication is common in obese men. It can be surgically corrected during c-section or plastic surgery, but divarication can reoccur.