ABSTRACT
The abdominal wall has a complex structure, and many of the surgical conditions affecting it are embryological in origin. It develops laterally from the vertebral column, envelops the intestinal tract, and finally fuses in the midline to form a seam-like fibrous cord, the linea alba. This is pierced at the umbilicus by the umbilical cord, which in early embryonic life contains the yolk sac and the entire mid-gut. A hernia is the protrusion of an organ or part of an organ through its containing wall. For an organ or tissue to herniate, there must be a weakness in the retaining wall. This may be caused by a congenital abnormality, may be related to the normal anatomy, such as a place where a vessel or viscus enters or leaves the abdomen, or may be acquired as a result of trauma or disease. All hernias that are related to the umbilicus may be called umbilical hernias.
