Hernia anatomy and repair. Sequence of illustrations (top to bottom) showing the development of an abdominal hernia and its repair with a mesh. A hernia occurs when an organ, such as a loop of the intestine, protrudes through the muscle layer at a weak area in the abdominal wall. The mesh strengthens the abdominal wall, preventing a recurrence of the condition. For this illustration without labels, see image C048/2730.