Human brain. Healthy brain cut in two sagittally, to show inner anatomical regions. The front of the brain is at left and right. The outer surface is covered in a network of dark blood vessels. The extensive folds and convolutions of the cerebrum (yellow) in two hemispheres, form most of the brain. The cerebrum is involved in conscious thought processes and voluntary body activity. In the hindbrain is the flower-shaped cerebellum (white) which coordinates muscle movement. The central brain has cavities (ventricles). The elongated white fibrous brainstem forms a stalk in the lower brain linked to the spinal cord. An adult human brain weighs about 1400 grams.