The human brain weighs about 3 pounds (1.4kg) and is divided into four main areas: the brain stem, cerebellum, diencephalon, and cerebrum. A healthy brain operates quickly and efficiently, but damage can disrupt its ability to function automatically and cause debilitating effects to the whole body.

Severe head trauma or other situations can cause damage to any of the exterior portions of the brain. Below are some of the main regions of the brain exterior and the bodily functions they control:

Brainstem

The lower extension of the brain connecting to the spinal cord. The brainstem controls basic survival functions such as breathing, digestion, heart rate, blood pressure, as well as your consciousness (being awake and alert).

Cerebellum

Located at the back of the brain, the cerebellum controls balance and muscle coordination. If this part of the brain is damaged, it may result in "ataxia," where the person loses muscle coordination. Ataxia may compromise a person's ability to walk, talk, eat, and take care of him or herself.

Cerebrum

The cerebrum has a wrinkled outer surface called the "cerebral cortex." It is the largest part of the brain and processes thought, language, memory, senses and movement. It is divided into four lobes, each managing specific tasks.

Frontal Lobe

Located at the front of the brain, the frontal lobe is involved in problem solving, behavior and emotions. This area of the brain forms a person's personality and contains the ability to plan, organize, focus attention, and overcome emotional issues.

The frontal lobe contains two distinct areas, the front "prefrontal cortex" that controls emotions, and back that controls premotor and motor areas.

Occipital Lobe

Region in the back of the brain that processes visual information. This is where you not only take in visual information, but it also contains areas that help you to recognize shapes and colors. Damage to this region of the brain can result in vision becoming impaired.

There are two parietal lobes located behind the frontal lobe at the top of the brain, separated by the central culcus. It also contains the primary sensory cortex that distinguishes touch and pressure and a large association area that distinguishes the more fine details of texture, weight, size and shape.

Parietal Lobe, Right

The right portion of the parietal lobe controls visuo-spacial recognition. If this area of the brain incurs damage, the person may find it dificult to navigate even the most familiar of places.

Parietal Lobe, Left

The left area of the parietal lobe processes language. Damage to this area may interfere with a person's ability to understand spoken and/or written words.

Temporal Lobe

At each side of the brain located near the ears are two temporal lobes that distinguish sound and smell. They also filter through new information and are believed to be responsible for short-term memory. The Right Lobe is mainly involved in visual memory of faces, pictures, images, etc. The Left Lobe is primarily involved in verbal memory of words, names, etc.

Left Hemisphere

The left portion of the brain processes mathematical, analytical and language-oriented information, as well as most functions on the right side of our bodies.

Right Hemisphere

The right portion of the brain processes creative, artistic, and spontaneous thoughts, as well as most functions on the left side of our bodies.

The Interior portions of the brain may be damaged as well, perhaps by disease or misuse of drugs. Below are the interior areas of the brain and what they control:

Pons

The pons resides within the brain stem and relays information about sensory and movement. It also regulates sleep.

Pituitary Gland

This gland is about the size of a pea, and it produces and distributes hormones that control bodily functions such as growth, hunger and sexual desire.

Pineal Gland

Slightly smaller than the pituitary gland, the pineal gland connects to the optic nerves to regulate sleep by releasing a sleep hormone called melatonin.

Thalamus

The thalamus acts as a command center, receiving information from the entire body and distributing it to the appropriate part of the brain for processing.

Fornix

This bundle of nerve fibers connects certain parts of the interior brain.

Corpus Callosum

This is a longer bundle of nerve fibers that connects and communicates between the two sides of our brain.

Midbrain

This sits at the top of the brain stem and delivers information about sight, hearing and body movement.

Medulla Oblongata

Located in the lower portion of the brain stem, this controls breathing, heartbeat and blood pressure.

Diencephalon

This region relays information about sensory input and central nervous and hormonal activity.

Neurons

A healthy brain contains about 100 billion neurons, or nerve cells, that convey messages through a network of trillions of nerve fibers called dendrites and axons.

Information comprised from National Geographic