A condition in which part of an internal organ projects abnormally through the wall of the cavity that normally contains it, especially the projection of the intestine from the abdominal cavity; a rupture: Hernias may be caused by failure of certain normal openings to close during development, weakness resulting from debilitating illness, old age, or injury, prolonged distention as from tumors, pregnancy, or corpulence, and increased intra-abdominal pressure resulting from lifting heavy loads or coughing.

A hernia may be present at birth, especially in the region of the navel, or caused by muscular strain or injury, or result from a congenital weakness in the cavity wall.

Treatment may include surgical or mechanical reduction. With very large hernias, mechanical devices or trusses may be used temporarily. A truss is a bandage consisting of a pad and belt; worn to hold a hernia in place by pressure.

A rupture in smooth muscle tissue protruding through a defect or weakened portion of the abdominal wall: An umbilical hernia is one type of abdominal hernia, or an abnormal protrusion of internal abdominal contents into a defect in the umbilical area which is common in a newborn child.

There are various hernias, as an "inguinal hernia", "umbilical hernia", or "spigelian hernia", in which an anatomical part, such as a section of the intestine, protrudes through an opening, tear, or weakness in the abdominal wall musculature which is a system or an arrangement of muscles in a body or a body part.