Structure, Parts, Functions, and Diagram of a Human Brain

The human brain is the control center of the body which is responsible for performing various functions such as emotional control, physical balance and nutrition. Along with this, the complex organ, the brain also controls sensation of our body including touch, maintenance of body temperature, appetite, smell, breathing etc.

The central nervous system (CNS) and the peripheral nervous system (PNS) together form a complete nervous system. The brain and spinal cord are parts of the CNS, while the PNS is composed of nerves and ganglia. In this article, we will discuss in detail about the human brain diagram, its parts and their important functions.

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The Human Brain

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The brain is an essential organ of the human body. The human brain works by receiving and processing information that our body encounters and sends the outcome to various regions of the body via neurons. According to recent estimates, the brain consists of nearly 86 billion to 100 billion neurons. Each and every processes in the human body is controlled by the CNS which consists of the spinal cord and the brain.

• On an average, the brain in adult humans weighs between 1.0 kg and 1.5 kg. 
• The human brain diagram has the same fundamental anatomy as other mammals.
• The only difference is that it is bigger and more evolved than other mammalian brains.
• The main functions of brain are to receive signals, process them, and send back messages to the body.
• It regulates all the body parts, their movements, thoughts, emotions, and the overall functioning of the body.

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Location of Brain

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Inside the skull, there is an organ surrounded by three layers of tissue and cerebrospinal fluid, which is called the human brain. The tissue that surrounds this organ is called the meninges whose primary role is to protect the brain from external shocks and pressure.

Cerebrospinal Fluid 

The cerebrospinal fluid or CSF is found within the tissues of the brain and spinal cord.It fills the empty areas on the brain's surface and protects it against immunological attacks. It acts as a buffer and protects the brain by cushioning mechanical shocks and neutralizing small jolts.

• On average, 500 ml of CSF is produced in a day by the specialized ependymal cells.
• Specifically, the brain is suspended in a layer of CSF, where its weight is almost nullified.
• This would cause neuron death in the afflicted area. 

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Human Brain Diagram

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The brain is surrounded by the skull which is a part of the skeletal system. It is made up of 22 bones with 14 are facial bones and 8 cranial bones. The skull protects the brain from the frontal, lateral, and dorsal directions. The brain is confined within the cranium and covered by cerebrospinal fluid or CSF. In the absence of CSF, the heavy weight of brain would restrict its movement, cutting off blood flow to the bottom part of the brain. The human brain diagram is given below: 

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Parts of Human Brain

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The human brain comprises of the following three parts:

• Forebrain
• Midbrain
• Hindbrain

Forebrain

The largest part of the human brain is called the forebrain. It is responsible for controlling emotions, hunger, sleep, body temperature, reproductive body parts, and functions. The forebrain further has three parts which are mentioned below:

• Cerebrum
• Thalamus
• Hypothalamus

Parts of Human Brain

Cerebrum

The Cerebrum or the cerebral cortex is the largest structure of the brain. The cerebrum controls the intellect, thinking process, reasoning, memory, consciousness, translation of touch, vision, and other senses. It consists of two cerebral hemispheres connected by thick, dense fiber brands known as the corpus callosum. The cerebrum is further divided into:

• Temporal Lobe: Temporal Lobe helps in processing sensory inputs, body orientation, and movements.
• Frontal Lobe: The frontal lobe is present under the forehead and is responsible for speech, reasoning, body movements, planning, and problem-solving. 
• Occipital Lobe: The Occipital Lobe is located at the backside of our brain and controls visual processing, distance perception, object and face recognition, color determination, and memory formation.
• Parietal Lobe: Parietal Lobe is responsible for controlling complex behaviors like perception of senses, which include taste, touch, smell, etc. It is present on the upper rear part of the brain.

The cerebrum has an exterior portion, known as the cortex, or the cerebral mantle. The cortex has a huge surface area because it is very convoluted and consists of three parts:

• Sensory Area- The sensory area is responsible for receiving messages.
• Motor Area- The Motor Area controls the action of voluntary muscles.
• Association Area- The association area establishes a connection between the sensory and the motor area.

Thalamus

The thalamus is a tiny structure just above the brain stem that is in charge of communicating sensory information from the sense organs and sending motor information for movement and synchronization.

Location: It located within the cerebrum's limbic system, which is primarily in charge of forming new memories and preserving old events.

Hypothalamus

The hypothalamus is a tiny and vital part of the human brain, positioned just underneath the thalamus. It is the main region of the brain and regulates all the important functions of the human body that are mentioned below:

• Controls the rate of heartbeat, appetite, blood pressure, and peristalsis.
• Regulates the temperature of the body.
• Responsible for controlling the emotion and mood
• Helps in synthesizing the essential hormones
• Controls the sense of smell and taste.
• Receives impulses from body parts. It also communicates messages from the autonomous nervous system.

Midbrain

Below the cerebral cortex and above the hindbrain is the midbrain. Its primary function is to act like a relay system, responsible for transmitting information required for hearing and vision. The midbrain is further divided into two parts:

• Tectum
• Tegmentum

Tectum

The tectum is a tiny part of the brain and refers specifically to the dorsal area of the midbrain. It sends and receives sensory information from the ears to the cerebrum and vice versa.

• The tectum is responsible for the reflex movements of the head, eye, and neck muscles.
• It serves as a channel for neurons that go in and out of the cerebrum.

Tegmentum

The tegmentum is located within the brainstem. It connects the midbrain to the cerebral, thalamus, and spinal cord. 

• It is a complex structure and has various components.
• It is primarily involved in sleep, bodily motions, attention, arousal, and various other body reflexes.

Hindbrain

The hindbrain is the central part of the brain. It regulates all the body functions required for survival like breathing, sleep, heart beating, motor learning, and consciousness. The hindbrain is made of three parts which are mentioned below:

• Cerebellum
• Medulla
• Pons

Cerebellum

• The cerebellum is present in the posterior area of the pons and medulla. The cerebellar tentorium and transverse fissure divide the cerebellum and cerebrum.
• It is the second biggest region of the human brain and consists of the cortex which has the outer surface and parallel ridges known as the folia. 
• The cerebellum also has cerebellar nuclei, cerebellar peduncles, posterior lobes, and anterior. It is divided into two halves - the outer grey cortex and the inner white medulla.
• It is in charge of regulating voluntary motions and maintaining bodily equilibrium during walking, cycling, running, and swimming.

Medulla Oblongata

The medulla is the tiny structure in the lowest part of the brain. It connects the cerebral cortex, spinal cord, and pons. 

• It regulates various body functions like breathing, heartbeat, digestion, etc.
• The medulla also maintains the body posture and control reflexes.

Pons

Pons is the main part of the brain stem. It lies between the medulla and the midbrain.

• It transmits signals to and fro from the spinal cord, midbrain, lower cerebellum, cerebrum, and the higher area of the brain. 
• Pons perform various important functions like controlling respiration and regulating the sleep cycle.
• It transmits the information or signals from the cerebellum to the motor cortex and vice versa.

Anatomy of Hindbrain

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Grey Matter and White matter

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The human brain has two types of tissues grey matter and white matter. We will discuss these types in detail.

Grey Matter and White Matter

Grey Matter

Grey matter consists of axon terminals, neural cell bodies, and dendrites. It is majorly present in the outermost layer of the brain.

• This matter is slightly pinkish-grey in color and surrounds the cerebrum, also known as the cortex of the brain.
• Grey matter makes up most of the brain and helps in processing and releasing new information.
• It develops at the time of fetal development and continues to increase at the age of 8 years old.

White Matter

White matter is present in the deeper tissues of the human brain (subcortical). It is composed of the axons (nerve fibers) and neurons (nerve cell extension)

• The axons are covered with a protected sheath called myelin, which is also responsible for the white color.
• Myelin also protects the nerve fibers from injury and also helps in the speedy transmission of signals.
• All the grey matter inside the brain is connected by the white matter.

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Functions of Brain

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Following are some of the important functions of human brain: 

• The brain functions in making decisions and memories.
• Thoughts and emotions are controlled by the brain.
• It controls physical functions like heart rate, breathing, body temperature, etc.
• It helps in responding to stress and other sensations like pain.
• Regulates the functioning of organs in our body. 
• Controls human language and speech. 

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Things to Remember

• The human brain performs physical functions, physiological processes, and cognitive skills.
• It is the central organ of the human body and is made up of 73% of water. 
• As compared to other mammalian brain, the human brain diagram is large and weighs about 1336 grams. 
• White and grey matter are the two types of tissues present in the human brain diagram. 
• The brain is surrounded by a skull, which is made up of 22 bones - 14 are facial bones and 8 are cranial bones.
• The Cerebrospinal Fluid or CFS fills the empty areas on the brain's surface.