Dictionary

abduction The movement of a limb away from the midline of the body. The opposite of abduction is adduction.

abducent nerve The sixth cranial nerve, which emerges from the skull to operate the lateral rectus muscle. This muscle draws the eye toward the side of the head. Paralysis of the abducent nerve causes inward turning of the eye.

abducens nerve See abducent nerve.

abdominal pain Pain in the belly. Abdominal pain can be acute or chronic. It may reflect a major problem with one of the organs in the abdomen, such as appendicitis or a perforated intestine, or it may result from a fairly minor problem, such as excess buildup of intestinal gas.

abdominal muscle One of a large group of muscles in the front of the abdomen that assists in maintaining regular breathing movements, supports the muscles of the spine while lifting, and keeps abdominal organs in place. Abdominal muscles are the target of many exercises, such as sit-ups. Abdominal muscles are informally known as the abs.

abdominal hysterectomy See hysterectomy, abdominal.

abdominal guarding Tensing of the abdominal wall muscles to guard inflamed organs within the abdomen from the pain of pressure upon them. Abdominal guarding is detected when the abdomen is pressed and is an indication that inflammation of the inner abdominal (peritoneal) surface may be present due, for example, to appendicitis or diverticulitis. The tensed…

abdominal cavity The cavity within the abdomen. This space between the abdominal wall and the spine contains a number of crucial organs, including the lower part of the esophagus, the stomach, small intestine, colon, rectum, liver, gallbladder, pancreas, spleen, kidneys, adrenal glands, ureters, and bladder. See also abdomen.

abdominal aortic aneurysm See aneurysm, abdominal aortic.

abdominal aorta The final section of the aorta, the largest artery in the body, which begins at the diaphragm as a continuation of the thoracic aorta and ends by splitting in two, to form the common iliac arteries. The abdominal aorta supplies oxygenated blood to all the abdominal and pelvic organs, as well as to…

abdomen The part of the body that contains all the structures between the chest and the pelvis. The abdomen, or belly, is anatomically separated from the chest by the diaphragm, the powerful muscle that spans the body cavity, just below the lungs. See also abdominal cavity.

ab- Prefix indicating from, away from, or off, as in abduction (movement of a limb away from the midline of the body) and abnormal (away from normal).