When an organ or tissue abnormally protrudes out of the body cavity, it’s called a hernia. The most common hernias, by far, develop in the adbdomen. In this case a weakeness in the abdonimal wall turns into a centralized hole, through which an organ or tissue will protrude.
Hernia’s are often times compared to the failure of the tire, where a split in the sidewall allows the inner tube to protrude through to the outside. In that example the inner tube of the tire is like the organ that breaks outwards through the opening in the sidewall. It is this pressure outwards, and the limit of restraint inwards that allows the bulge to develop.
Besides the hernia’s that can develop in the adbomen there is several others:
Internal hernia – hernia into or involving an intraabdominal structure
Spigelian hernia – hernia through the linea semilunaris
Sliding hernia – the hernia sac is partially formed by the wall of a viscus
Littre’s hernia – hernia involving a Meckel’s erticulum
obturator hernia – hernia through obturator canal