Dictionary

melanocyte A cell in the skin that produces and contains the pigment melanin.

Meckel diverticulum See diverticulum, Meckel.

meconium Dark, sticky material that is normally present in the intestine at birth and passed in the feces after birth, after trypsin and other enzymes from the pancreas have acted on it. The passage of meconium before birth can be a sign of fetal distress.

meconium ileus Obstruction of the intestine (ileus) due to overly thick meconium. Meconium ileus results from a deficiency of trypsin and other digestive enzymes from the pancreas, as in cystic fibrosis.

medial collateral ligament of the knee The ligament that straps the inner side of the knee joint, providing stability and strength. See also knee.

medial meniscus of the knee A thickened, crescent-shaped cartilage pad in the inner portion of the joint formed by the femur (the thigh bone) and the tibia (the shin bone). The medial meniscus is in the inner side, whereas the lateral meniscus is in the outer side of this knee joint. The meniscus acts as…

median The middle, as in the median strip in a highway. For example, the median nerve is the nerve the runs through the middle of the wrist.

mediastinoscopy A procedure in which the physician inserts a tube into the chest to view the organs in the mediastinum. The tube is inserted through an incision above the breastbone.

mediastinotomy The surgical opening of the mediastinum. See also mediastinum; mediastinoscopy.

mediastinum The area between the lungs. The organs in the mediastinum include the heart and its large veins and arteries, the trachea, the esophagus, the bronchi, and lymph nodes.

Medicaid A number of US programs of public assistance for persons whose income is insufficient to pay for health care, regardless of age. Medicaid is administered on a state level, with the federal government providing matching funds to state Medicaid programs. Services and options can vary from state to state. Disabled persons who receive Social…

Medical College Admissions Test A test that is required of all applicants to medical school in the US and Canada, which assesses applicants’ science knowledge, reasoning, and communication and writing skills. It is given under the aegis of the Association of American Medical Colleges. Abbreviated MCAT.