abdomen

The abdomen (also known as the abdominopelvic region) is the region of the body situated between the thorax (chest) and the pelvis. It contains the abdominal cavity, which houses many vital organs including the stomach, intestines, liver, kidneys, and spleen. The dorsal (back) part of the abdomen is anchored by the lumbar vertebral column.

The abdomen is located between the thorax (chest) above and the pelvis below. Its superior boundary is the diaphragm, and its inferior boundary transitions into the pelvic cavity. The abdominal cavity is lined by the peritoneum and contains organs of the digestive, urinary, and endocrine systems.

The abdomen serves as the body's central compartment for digestion, metabolism, urinary filtration, and reproductive functions. It houses organs such as the stomach, liver, pancreas, intestines, and kidneys, which collectively process nutrients, filter waste, and produce essential biochemicals. The muscular abdominal wall supports posture, aids in breathing, and protects the visceral organs.

The abdomen can be affected by a wide range of conditions including appendicitis, hernias, peptic ulcers, pancreatitis, liver disease, and colorectal cancer. Acute abdominal pain is a common clinical presentation requiring careful evaluation to identify potentially life-threatening causes. Imaging techniques such as ultrasound and CT scanning are essential tools for diagnosing abdominal conditions.

The abdomen is often distinguished from the thorax, which lies above it and contains the heart and lungs, and from the pelvis, which lies below it and contains the reproductive organs and bladder. While the thorax is protected by the rib cage and sternum, the abdomen has a more flexible muscular wall, which allows for the distension of digestive organs. The peritoneal cavity within the abdomen is lined by a serous membrane (peritoneum), a feature not shared by the thoracic or pelvic cavities in the same way.