The brain is the hub of the nerve system and controls all body functions and processes. The brain, that has the consistency of gelatin, is held together by 3 layers of membranes called the dura, pia, and arachnoid. Between the pia and arachnoid membranes is the subarachnoid space, through which a network of arteries and veins transports blood from the heart. The brain is encompassed by a cushioning reservoir of cerebrospinal fluid. The lower part of the brain passes through a hole at the base of the skull and merging with the spinal cord and the rest of the nerve system.
The brain stem can be compared to a phone cable with thousands of individual wires that carry signals from all portions of the body. The brain stem also regulates such body functions as consciousness, fatigue, heart rate, and blood pressure level. Damage to the stem may cause loss of consciousness or concussion of the brain. Behind the brain stem is the cerebellum, a curved mass of nerve tissues which regulates the balance and coordinates fine motor skills. The right hemisphere controls the left side of the body, the left hemisphere controls the right side. In many people, the left hemisphere regulates language and speech and the right hemisphere controls nonverbal, spatial skills like the capability to draw or play music.
An injury to the left side of the brain influences speech and movement on the right side of the body. The cerebral cortex is more divided into several areas called lobes. Of those: The right and left frontal lobes, located behind the forehead, control intellectual activities, like the capability to organize, and figure prominently in character, behavior, and emotional control. The temporal lobes, situated instantly behind and beneath the frontal lobes and just behind the ears, control memory, speech, and comprehension. The parietal lobes located at the rear of the head and over the years, control the capability to read, write, and understand spatial relationships.
The areas between the frontal and parietal lobes regulate movement and sensation. The occipital lobes, situated at the rear of the head, control sight. At the center of the cerebral cortex are several small white nuclei, or nerve centers, called the diencephalon. Amongst these is the pea-sized hypothalamus, that regulates appetite, thirst, temperature, and some aspects of memory and control excitement sexual.