accessory nerve The eleventh cranial nerve, which emerges from the skull and receives an additional (accessory) root from the upper part of the spinal cord. It supplies the sternocleidomastoid and trapezius muscles.
accelerated phase of leukemia Chronic myelogenous leukemia that is progressing. In this phase, the number of immature, abnormal white blood cells in the bone marrow and blood is higher than in the chronic phase, but not as high as in the blast phase.
acapnia Lower than normal level of carbon dioxide in the blood. The opposite of acapnia is hypercapnia.
acanthosis nigricans A skin condition characterized by dark, thickened, velvety patches, especially in the folds of skin in the armpit, groin, and back of the neck. It can occur with endocrine diseases such as Cushing disease and diabetes mellitus, from tumors of the pituitary gland, underlying malignancies, certain drugs, and as a genetic disorder. It…
AC joint See acromioclavicular joint.
a.c. Abbreviation of the Latin phrase ante cibum, meaning “before meals.” See also Appendix A, “Prescription Abbreviations.”
abstinence The voluntary self-denial of food, drink, or sex. Today, abstinence most commonly refers to denial of one’s sexual activity.
absorption Uptake. For example, intestinal absorption is the uptake of food (or other substances) from the digestive tract.
absolute CD4 count The number of “helper” Tlymphocytes in a cubic millimeter of blood. The absolute CD4 count is frequently used to monitor the extent of immune suppression in persons with HIV because with HIV, this number declines as the infection progresses. Also known as T4 count.
absinthe An emerald-green liqueur flavored with extracts of the wormwood plant, licorice, and aromatic flavorings in an alcohol base. Absinthe was manufactured, commercialized, and popularized in France in the late 1700s. It was an extremely addictive drink. Prolonged drinking of absinthe causes convulsions, blindness, hallucinations, and mental deterioration. Absinthe has been banned, but something of…
absence of the nipple See athelia.
absence of the breast See amastia.