brain

the part of the CENTRAL NERVOUS SYSTEM contained within the cranium that is connected via the spinal cord to the remainder of the nervous system. The brain interprets information received from sense organs and emits signals to control muscles. The brain comprises distinct areas: the CEREBRUM , CEREBELLUM , PONS , MEDULLA OBLONGATA and mid-brain or MESENCEPHALON . GREY MATTER and WHITE MATTER make up the brain, in different arrangements, and a dense network of blood vessels supplies the grey matter, and both blood vessels and nerve cells are supported by a fibrous network, the NEUROGLIA . The average female brain weighs 1.25 kg, and the male 1.4 kg and the maximum size occurs around the age of 20, whereupon it decreases gradually. Three membranes (the MENINGES ) separate the brain from the skull, and between each pair is a fluid-filled space to cushion the brain. There are twelve nerves connected to the brain, mainly in the region of the brain stem, and four arteries carrying blood to the brain. Two veins drain the central portion and many small veins open into venous SINUSES that connect with the internal jugular vein.