Braxton Hicks contraction An irregular contraction of the womb (uterus) that occurs toward the middle of a woman’s first pregnancy and earlier, and more intensely, in her subsequent pregnancies. Braxton Hicks contractions tend to occur during physical activity. The uterus tightens for 30 to 60 seconds, beginning at the top of the uterus, and the…
branchial cyst See branchial cleft cyst.
branchial cleft cyst A cavity that is a remnant from embryologic development and is still present at birth in one side of the neck, just in front of the large angulated muscle on either side (the sternocleidomastoid muscle). The cyst may not be recognized until adolescence, when it enlarges its oval shape. Sometimes a branchial…
brain ventricle One of the communicating cavities within the brain. There are four ventricles: two lateral ventricles, the third ventricle, and the fourth ventricle. The lateral ventricles are in the cerebral hemispheres. Each lateral ventricle consists of a triangular central body and four horns. The lateral ventricles communicate with the third ventricle through the interventricular…
brain tumor A benign or malignant growth in the brain. Primary brain tumors initially form in brain tissue. Secondary brain tumors are cancers that have spread (metastasized) to the brain tissue from tissue elsewhere in the body. Brain tumors can occur in people of any age.
brain stem glioma A type of brain tumor that involves the glial cells.
brain stem The stem-like part of the base of the brain that is connected to the spinal cord. The brain stem controls the flow of messages between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is…
brain plasticity The phenomenon of change and learning in the adult brain. Also known as brain malleability.
brain malleability See brain plasticity.
brain freeze A headache that occurs when one puts ice, a cold food, or a chilled beverage in the mouth, chilling the roof of the mouth. Ice cream is by far the most frequent offender. Brain freeze is characterized by a stabbing, aching pain that begins a few seconds after ingestion of something cold. The…
brain death The permanent, irreversible cessation of all brain functions. Brain death is not the same thing as a coma or vegetative state. The presence of brain death is legally synonymous with death itself in most US states.
brain cancer A malignant growth of the brain. See also brain tumor.