spiral CAT scan A specialized computerized axial tomography (CAT) scan technique that involves continuous movement of the patient through the scanner with the ability to scan faster and with high definition of internal structures. Spiral CAT scanning permits greater visualization of blood vessels and internal tissues, such as those within the chest cavity, than regular…
spiral fracture See fracture, torsion.
spirochete A microscopic bacterial organism in the Spirochaeta family that has a worm-like, spiralshaped form and wiggles vigorously when viewed under a microscope. Treponema pallidum, the cause of syphilis, is a particularly well-known spirochete.
spleen An organ that is located in the upper-left part of the abdomen, not far from the stomach, that produces lymphocytes, which are important elements in the immune system. The spleen is the largest lymphatic organ in the body. The spleen also filters blood, serves as a major reservoir for blood, and destroys blood cells…
spleen, ruptured Rupture of the capsule of the spleen that is a potential catastrophe and requires immediate medical and surgical attention. Splenic rupture permits large amounts of blood to leak into the abdominal cavity, and it is severely painful and life threatening. Shock, and ultimately death, can result. Patients typically require immediate surgery. Rupture of…
S1–S5 Symbols that represent the five sacral vertebrae.
spasm A brief, automatic jerking movement. A muscle spasm can be quite painful, with the muscle clenching tightly. A spasm of the coronary artery can cause the pain of angina. Spasms in various types of tissue may be caused by stress, medication, and overexercise.
spastic colitis See irritable bowel syndrome.
spasticity See hypertonia.
specific developmental disorder See developmental disorder, specific.
specific-pathogen free A term that is applied to animals reared for use in laboratory experiments which indicates that the animals are known to be free of germs that can cause disease. Abbreviated SPF.
speckled iris See Brushfield spot.