Webster's New World Medical Dictionary

brain malleability
See 
brain plasticity.
brain plasticity
The phenomenon of change and
learning in the adult brain. Also known as brain 
malleability.
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 awake or sleepy. The brain stem con-
sists of the midbrain, pons, and medulla oblongata.
brain stem glioma
A type of brain tumor that
involves the glial cells.
brachial plexus
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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 ventricle
One of the communicating cavi-
ties 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 tri-
angular central body and four horns. The lateral
ventricles communicate with the third ventricle
through the interventricular foramen (opening).
The third ventricle is a median (midline) cavity in
the brain, bounded by the thalamus and hypothala-
mus on either side. In front, the third ventricle com-
municates with the lateral ventricles, and in back it
communicates with the aqueduct of the midbrain
(the aqueduct of Sylvius). The fourth ventricle is the
most inferior of the four ventricles of the brain. It
extends from the aqueduct of the midbrain to the
central canal of the upper end of the spinal cord,
with which it communicates by the two foramina
(openings) of Luschka and the foramen of
Magendie. The ventricles are filled with cere-
brospinal fluid, which is formed by structures,
called choroid plexuses, that are located in the walls
and roofs of the ventricles.