The abdomen is the part of the body that lies between the chest and the pelvis and encloses the stomach, intestines, liver, spleen, and pancreas. Also called belly, venter.
The abdomen contains most of the tubelike organs of the digestive tract, as well as several solid organs. Hollow abdominal organs include the stomach, the small intestine, and the colon with its attached appendix. Organs such as the liver, its attached gallbladder, and the pancreas function in close association with the digestive tract and communicate with it via ducts. The spleen, kidneys, and adrenal glands also lie within the abdomen, along with many blood vessels including the aorta and inferior vena cava. Anatomists may consider the urinary bladder, uterus, fallopian tubes, and ovaries as either abdominal organs or as pelvic organs (see genitourinary). Finally, the abdomen contains an extensive membrane called the peritoneum. A fold of peritoneum may completely cover certain organs, whereas it may cover only one side of organs that usually lie closer to the abdominal wall.
The gastrointestinal tract (GI tract), also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. The major functions of the GI tract are digestion and excretion.
Upper gastrointestinal tract
The upper GI tract consists of the mouth, pharynx, esophagus, and stomach. The upper GI tract roughly corresponds to the derivatives of the foregut, with the exception of the first part of the duodenum.
Lower gastrointestinal tract
The lower GI tract comprises the bowel or intestine (small intestine and large intestine) and anus.
Abdominal and Gastrointestinal Radiology (or Imaging)
The subspecialty concerned with diagnostic radiology of the abdomen/gastrointestinal tract (including the stomach and intestines).