Abdomen

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Abdomen in anatomy, is the cavity of the body between the chest and the pelvis in humans and all other vertebrates. The abdominal cavity contains major organs of the digestive, urinary, and reproductive systems.

Unlike the skull and the chest cavity, bones do not surround the abdomen. This allows the abdominal cavity to vary in size and shape. Three layers of muscles in front and on the sides of the abdomen, together with the spine and back muscles, form abdominal walls that support the internal organs.

Major organs of the abdomen include the stomach, liver, small intestine and large intestine, gallbladder, pancreas, spleen, kidneys, adrenal glands, and bladder. In a female, the abdomen holds the uterus and ovaries. In a male, it holds the prostate gland. A two-layered membrane, the peritoneum, surrounds the abdominal organs. The peritoneum produces serous fluid, a clear, watery substance that lubricates the outer membrane to prevent friction as it moves against the abdominal walls.

The major artery in the abdomen is the aorta, which carries blood from the heart. The inferior vena cava is the major abdominal vein returning blood to the heart.

The term abdomen also refers to the posterior section of insects and other arthropods.

See abdominal pain

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