The brain is encased by the cranium, bones of the skull which immediately cover and protect brain surfaces. A thin cover of
skin, called the scalp, covers most of the cranium. The largest part of the brain immediately beneath the bones of the cranium
is the cerebral cortex. The cerebral cortex is composed of nerve cells (neurons,) many of which are functionally connected
to each other, and connected to other parts of the brain. Electrical activity in the form of nerve impulses being sent and
received to and from cortical neurons is always present, even during sleep. In a biological sense (as well as a medical or legal
sense,) absence of electrical activity in the human cerebral cortex signifies death.
Functions of the cerebral cortex include abstract thought, reasoning, voluntary and involuntary control of skeletal muscle, and
the recognition and differentiation of somatic, visceral, and special sensory stimuli. Specific regions of the cerebral cortex
process or generate various kinds of information. For example, the occipital lobe processes visual information while the
parietal lobe processes somatosensory information such as cutaneous pain or temperature (Fig. 3.1).