apraxia of speech A severe speech disorder characterized by an inability to speak or a severe struggle to speak clearly. Apraxia of speech occurs when the oral-motor muscles do not or cannot obey commands from the brain or when the brain cannot reliably send those commands. Apraxia of speech is caused by damage to the…
apraxia The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function. Apraxia is not related to a lack of understanding or to any kind of physical paralysis; rather, it is caused by a problem in the cortex of the brain.
apposition 1 The act of adding or accretion. Growth by apposition is characteristic of many tissues in the body by which nutritive matter from the blood is transformed on the surface of an organ into a solid unorganized substance. 2 The act of putting things in juxtaposition or side by side. To lose a pair…
appendix testis A small solid projection of tissue on the outer surface of the testis, which is a remnant of the embryologic mullerian duct.
appendix epiploica A finger-like projection of fat attached to the colon.
appendix epididymis A small cystic projection from the surface of the epididymis (a structure within the scrotum that is attached to the backside of the testis), which represents a remnant of the embryologic mesonephros.
appendix A small outpouching from the beginning of the large intestine.
appendicitis Inflammation of the appendix, usually associated with infection of the appendix. Appendicitis often causes fever, loss of appetite, and pain. Appendicitis may be suspected because of the medical history and physical examination. The pain of appendicitis can be located in various areas of the belly. If the appendix ruptures and infection spreads throughout the…
appendectomy Surgical removal of the appendix. An appendectomy is performed because of probable appendicitis. See also appendicitis.
apoptosis A form of cell death in which a programmed sequence of events leads to the elimination of cells without releasing harmful substances into the surrounding area. Apoptosis plays a crucial role in developing and maintaining the health of the body by eliminating old cells, unnecessary cells, and unhealthy cells. The human body replaces perhaps…
apophysitis calcaneus Inflammation of the growth plate of the calcaneus, the bone at the back of the heel, where the Achilles tendon attaches. Apophysitis calcaneus occurs mainly in older children and adolescents, especially active boys. It can be very painful, although it may be dismissed as “growing pains.” Treatment includes activity limitation, medication, shoe inserts,…
apnea The absence of breathing (respiration).