Together, the brain and spinal cord make up the central nervous system (CNS). The brain controls the way we think, feel, learn, and move. It also controls other bodily functions without our having to think about it, such as breathing and heart rate. The brain is protected by the bones of the cranium.

The spinal cord is composed of nerves (nervous system) located along the trunk (spinal column). The brain sends messages to the different parts of the body through the spinal cord. The spinal cord begins at the bottom of the brain and continues down into the lower back. The bones of the spine protect the spinal cord.

The brain and spinal cord are covered and protected by three layers of tissue (membranes) called the meninges. The area between two of these layers is called the subarachnoid space. It contains a liquid cerebrospinal fluid, which acts as a cushion to protect the brain. This fluid also contains certain nutrients for the brain and eliminates certain waste products.

  • The nerve cells (neurons)

The brain is made up of billions of nerve cells called neurons. They communicate amongst themselves and with other parts of the body by sending messages (nerve impulses) through a network of nerves.

The nerve cells are maintained and supported with the support of the glial cells. There are different types of glial cells, including astrocytes, oligodendrocytes, and ependymal cells. Unlike other cells in the body, nerve cells cannot replace themselves. They gradually decrease as we age.


  • Main areas of the brain

The main parts of the brain and the brain itself, the cerebellum, the cerebellum, the brainstem, and the pituitary gland.

- Brain

This is the biggest part of the brain and is made up of two halves (hemispheres). It controls thought, memory, and personality. The right half of the brain controls the left side of the body, and the left part of the brain controls the right part of the body.

Both halves of the brain are divided into four areas, or lobes:

  • The frontal lobe is responsible for thought, memory, planning, problem solving, and behavior. The part of the frontal lobe located near the uppermost part of the brain controls the movement of the arms and legs.
  • The parietal lobe helps us form words. It is also responsible for touch and other senses as well as our knowledge of the body's position.
  • The temporal lobe is responsible for our emotions, the way we understand things to be, and the way we process what we hear and smell. It also helps us organize information and learn.
  • The occipital lobe processes information about what we see, such as color, shape, and distance.

- Cerebellum

This is located beneath the brain and toward the back. It controls balance and coordination.

- Brainstem

The brainstem is in the lower part of the brain and is connected to the spinal cord. It controls essential bodily functions for our survival, such as breathing, heart rate, blood pressure, and body temperature. It also controls the movements of the eye and our ability to swallow.

- Pituitary gland

The pituitary gland is located just below the base of the brain. It separates hormones that make it possible to regulate homeostasis, including hormones that regulate the functioning of other glands included in the endocrine system.