Epilepsy:  A disorder characterized by abnormal electrical discharges in the brain, causing abnormal sensation, movement or level of consciousness. More about epilepsy in adults and epilepsy in children.
Facet:  A small, smooth-surfaced end of a bony projection (articular process) that functions as part of a joint.
Facet joint:  Each of four joints formed above, below, and on either side of a vertebra. The lower bony projection of one vertebra meets the upper projections of the vertebra below it, forming facet joints.
Facetectomy:  Surgical removal of one of the facets; excision of a facet joint.
Falx cerebri:  An extension of dura between the right and left hemispheres of the brain.
Fontanelle:  Normal openings in the skull of infants. The largest of these is the anterior fontanelle, the "soft spot" in the middle of the head. More about craniofacial anomalies.
Foramen:  A hole or opening that acts as a passageway for nerves or blood vessels.
Foraminotomy:  Surgical enlargement of the foramen/foramina.
Fractionated therapy:  Stereotactic radiation that is given in multiple lower-dose treatments rather than in a single session. More about our Stereotactic Radiotherapy Program
Fusiform aneurysm:  A sausage-like enlargement of the blood vessel.
Gamma knife:  Equipment that precisely delivers a concentrated dose of radiation to a predetermined target using gamma rays. More about stereotactic radiosurgery.
Glasgow coma scale (GCS):  The most widely used system of classifying the severity of head injuries or other neurologic diseases.
Glasgow outcome scale:  A widely used system of classifying outcome after head injury or other neurologic diseases.
Glia (glial cells):  The major support cells of the brain. These cells are involved in the nutrition and maintenance of the nerve cells.
Glioblastoma:  A rapidly growing tumor composed of primitive glial cells, mainly arising from astrocytes. More about glioblastoma multiforme (GBM).
Glioma:  A tumor formed by glial cells.
Globus pallidus:  Part of the basal ganglia, which are brain cells that lie deep in the brain.
Greater occipital nerve:  A branch of the second cervical spinal nerve that innervates the middle portion of the occipital area (at the back of the skull) of the scalp.
Hemangioma:  An aggregation of multiple dilated blood vessels.
Hematoma:  A blood clot.

Weill Cornell Medicine Brain & Spine Center 525 East 68 Street, Box 99 New York, NY 10065 Phone: 866-426-7787