The brain is the main organ of the central nervous system inside the skull. Brain symptoms include physical brain symptoms (e.g. headache, motor symptoms) and mental health symptoms (e.g. anxiety, depressive symptoms). Brain disorders include physical brain disorders (neurological disorders) such as stroke, brain injury, concussion, Parkinson’s Disease, Alzheimer’s Disease, and so on, along with various psychological or psychiatric disorders such as clinical depression, schizophrenia, and other brain disorders.

   •   •   •

Brain: The part of Central Nervous System that is contained within the skull (Cranium). Arising from the Neural Tube, the embryonic brain is comprised of three major parts including Prosencephalon (the forebrain); Mesencephalon (the midbrain); and Rhombencephalon (the hindbrain). The developed brain consists of Cerebrum; Cerebellum; and other structures in the Brain Stem.1

   •   •   •

Brain adverse event: An adverse event that occurs in brain.2

Anatomical Information about Brain

The brain has three major parts:

  • The cerebrum is the largest part of the brain. It is at the top of the head. The cerebrum controls thinking, learning, problem solving, emotions, speech, reading, writing, and voluntary movement.
  • The cerebellum is in the lower back of the brain (near the middle of the back of the head). It controls movement, balance, and posture.
  • The brain stem connects the brain to the spinal cord. It is in the lowest part of the brain (just above the back of the neck). The brain stem controls breathing, heart rate, and the nerves and muscles used in seeing, hearing, walking, talking, and eating.

Source: NCI (NIH)3

   •   •   •

Anatomy of the brain. The supratentorial area (the upper part of the brain) contains the cerebrum, lateral ventricle and third ventricle (with cerebrospinal fluid shown in blue), choroid plexus, hypothalamus, pineal gland, pituitary gland, and optic nerve. The posterior fossa/infratentorial area (the lower back part of the brain) contains the cerebellum, tectum, fourth ventricle, and brain stem (pons and medulla). The tentorium separates the supratentorium from the infratentorium (right panel). The skull and meninges protect the brain and spinal cord (left panel).

Source: NCI (NIH)4

   •   •   •

How Brain Cells Work

The healthy human brain contains many different types of cells. Neurons are nerve cells that process and send information throughout the brain, and from the brain to the muscles and organs of the body.

The ability of neurons to function and survive depends on three important processes:

  • Communication. When a neuron receives signals from other neurons, it generates an electrical charge. This charge travels to the synapse, a tiny gap where chemicals called neurotransmitters are released and move across to another neuron.
  • Metabolism. This process involves all chemical reactions that take place in a cell to support its survival and function. These reactions require oxygen and glucose, which are carried in blood flowing through the brain.
  • Repair, remodeling, and regeneration. Neurons live a long time—more than 100 years in humans. As a result, they must constantly maintain and repair themselves. In addition, some brain regions continue to make new neurons.

Other types of brain cells, called glial cells, play critical roles in supporting neurons. In addition, the brain has an enormous network of blood vessels. Although the brain is only 2 percent of the body's weight, it receives 20 percent of the body's blood supply.

See more resources about cognitive health.

Source: NIA (NIH)5

Anatomy Articles

Read about these related anatomy topics:

Symptom Articles

Read about these related symptoms:

Disease and Condition Articles

Read about these related conditions and diseases:

Related Symptom Topics

Read more about these related symptoms:

... More »

Related Disease and Condition Topics

Read about these diseases and medical conditions related to Brain:

... More »

   •   •   •


  1. Source: MeSH (U.S. National Library of Medicine)
  2. Source: OAE Ontology
  3. Source: NCI (NIH): types/ brain/ patient/ child-brain-treatment-pdq
  4. ibid.
  5. Source: NIA (NIH): health/ how-aging-brain-affects-thinking

   •   •   •

Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.