The supramarginal gyrus is a portion of the parietal lobe. This area of the brain is also known as Brodmann area 40. It is probably involved with language perception and processing, and lesions in it may cause receptive aphasia.
This definition incorporates text from the wikipedia website - Wikipedia: The free encyclopedia. (2004, July 22). FL: Wikimedia Foundation, Inc. Retrieved August 10, 2004, from http://www.wikipedia.org