Brain Anatomy and Parts of the Brain

Brain is a part of the central nervous system, which functions as the primary receiver, organizer and distributor of information of the body. It regulates all the major activities of the body such as perception, cognition, attention, emotion, memory, and action. It is estimated that brain is made up of 50 - 100 billions of nerve cells. It is suspended in the cerebrospinal fluid, continuous with the spinal cord (structure made up of neurons and nerve fibers) and enclosed within the skull.

The brain is separated from the bloodstream by a cellular structure known as the blood-brain barrier. This barrier also acts as a filter and restricts the passage of chemical substances and microscopic particles inside the brain. However, it allows access to only those substances responsible for metabolism, for example, oxygen. It is due to this fact that infection of the human brain is rare, as compared to other organs of the body. However, many of the psychiatric and genetically inherited diseases, for example, schizophrenia and multiple sclerosis respectively, are caused due to dysfunctions of the brain.

Brain Anatomy: Different Parts of the Brain

Talking about brain parts, it is made up of three major segments - forebrain, midbrain and hindbrain. Each segment consists of different interdependent parts. Let's see in detail about the anatomy and parts of the brain.

The Forebrain
The forebrain is the largest segment of the brain located in the uppermost part of the brain. It consists of the cerebrum, the thalamus and the hypothalamus.

Cerebrum- The cerebrum or the cortex is the largest part of the brain. Its functions include thinking, reasoning and remembering. The cerebrum is separated into two hemispheres (right and left) by a deep groove called the longitudinal cerebral fissure. The right hemisphere controls the right side of the body and vice versa. Each hemisphere is again divided into four sections or lobes, namely, frontal, parietal, occipital, and temporal lobe. Each of the four lobes is responsible for specific activities. Frontal lobe is responsible for personality characteristics, parietal lobe controls interpretation of pain, occipital lobe is involved with vision and temporal lobe is responsible for memory, smell and speech.

The outer layer of the cerebrum is composed mostly of nerve cells, which is called gray matter and controls the activity of the brain; the inner portion is made up of axons (nerve fibers) called white matter. The axons, which are covered by myelin sheath, are responsible for transferring information in between the nerve cells.

Thalamus and Hypothalamus- Thalamus is a part of brain consisting of two ovoid structures, which are composed of a large mass of gray matter. It is situated deep inside the forebrain, at the base of the cerebrum. The functions of thalamus include both sensory behavior and motor behavior.

Hypothalamus is referred to as "the brain of the brain". The main function of hypothalamus is homeostasis and controls all the autonomic regulatory activities of the body such as temperature and cardiovascular regulation.

The Midbrain
The midbrain or mesencephalon is the topmost section of the brainstem ((lower part of the brain adjoining the spinal cord). It is made up of the tectum and tegmentum and the cerebral peduncles (paired bundle of nerve fibers that carries melanin pigment).

Tectum- The tectum is a roof-like structure, which forms the dorsal part of the midbrain. It consists of the superior and inferior colliculi, which represent the anterior and posterior pair of nuclei of the tectum. The superior and inferior colliculi control vision and audition respectively.

Tegmentum- Tegmentum on the other hand is the ventral portion of the midbrain that lies within the brainstem. It controls the motor function and regulates other autonomic functions.

The Hindbrain
In the brain diagram, the hindbrain is actually located at the upper portion of the spinal cord and is responsible for the vital functions of the body such as respiration and heartbeat. It actually consists of the cerebellum, pons and medulla.

Cerebellum- Cerebellum is also referred to as "little brain" and contains more than 50% of the total neurons. It is situated at the lower side of the brain, in between the cerebrum and the brain stem. Cerebellum is divided into two hemispheres and overall, contains 10 lobules. The two hemispheres are connected by white fibers. Like cerebrum, cerebellum also contains gray matter. Cerebellum controls and regulates coordination of movements.

Pons and Medulla- Pons and medulla are parts of the brainstem that connects the brain and the spinal cord. Pons consists of the control centers for face and eye movements. It contains the origins of 5th, 6th, 7th and 8th cranial nerves. Medulla is located at the lowest part of the brainstem and contains control centers for heart and lungs. The cranial nerves 9th, 10th, 11th, and 12th originate from medulla.