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.

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