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The central nervous system primarily consists of the brain and the spinal cord.

The nervous system in humans can be broadly classified into two types, namely, the peripheral nervous system and central nervous system

The central nervous system primarily consists of the brain and the spinal cord. The system coordinates and controls various aspects of life, ranging from physical attributes (heartbeat, breathing) to mental capabilities (memory, intelligence).

The nerves and ganglia that are present outside the brain and spinal cord contribute to the peripheral nervous system. The primary role of the PNS is to connect the central nervous system to the rest of the body, such as the limbs, skin.

The brain is enclosed within the skull, where it is suspended in a layer of fluid called the cerebrospinal fluid. It protects the brain from minor mechanical shocks and jolts. Furthermore, it also serves minor immunological roles and provides the necessary nutrients required by the brain.

Anatomically, the brain consists of the following parts:












The human brain controls nearly every aspect of the human body ranging from physiological functions to cognitive abilities. It functions by receiving and sending signals via neurons to different parts of the body. The human brain, just like most other mammals, has the same basic structure, but it is better developed than any other mammalian brain. Table of Contents

Read on to explore the human brain structure, diagram, parts of the human brain and the body functions controlled by the human brain. Also Read:  Placebo effect Find out how some people live with just half a brain.

On average, an adult brain weighs between 1.0 kg – 1.5 kg.  It is mainly composed of neurons – the fundamental unit of the brain and nervous system. Recent estimates have suggested that the brain contains anywhere between 86 billion to 100 billion neurons.

The  brain , along with the  spinal cord , constitutes the central nervous system. It is responsible for thoughts, interpretation and origin of control for body movements.

The brain diagram given below highlights the different lobes of the human brain.

The brain is enclosed within the skull, which provides frontal, lateral and dorsal protection. The skull consists of 22 bones, 14 of which form the facial bones and the remaining 8 form the cranial bones. Anatomically, the brain is contained within the cranium and is surrounded by the cerebrospinal fluid.

The Cerebrospinal Fluid (CSF) is a fluid that circulates within the skull and spinal cord, filling up hollow spaces on the surface of the brain. Every day, the specialised ependymal cells produce around 500mL of cerebrospinal fluid.

The primary function of the CSF is to act as a buffer for the brain, cushioning mechanical shocks and dampening minor jolts. It also provides basic immunological protection to the brain.

Furthermore, CSF provides buoyancy for the brain. i.e., the brain is suspended in a layer of CSF, wherein, the weight of the brain is nearly negated. If the brain is not suspended in CSF, it would be impeded by its weight, consequently cutting off the blood supply in the lower half of the brain. It would lead to the death of neurons in the affected area.

Following are the major parts of the human brain:

It is the anterior part of the brain. The forebrain parts include:

Forebrain Function:  Controls the reproductive functions, body temperature, emotions, hunger and sleep. Fact : The largest among the forebrain parts is the cerebrum. It is also the largest part of all vertebrate brains.

Hindbrain functions:  The three regions of the hindbrain coordinates all processes necessary for survival. These induce breathing, heartbeat, sleep, wakefulness and motor learning.

Brain diagram highlighting various parts of the human brain

The cerebrum is the largest part of the brain. It consists of the cerebral cortex and other subcortical structures. It is composed of two cerebral hemispheres that are joined together by heavy, dense bands of fibre called the corpus callosum. The cerebrum is further divided into four sections or lobes:

Frontal lobe : It is associated with parts of speech, planning, reasoning, problem-solving and movements.

Parietal lobe : Help in movements, the perception of stimuli and orientation.

Occipital lobe : It is related to visual processing.

Temporal lobe : This region is related to perception and recognition of memory, auditory stimuli and speech.

The brain consists of two types of tissues: Grey matter and White matter .

The exterior portion of the cerebrum is called the cortex or the cerebral mantle. The cortex is extremely convoluted, due to which, it has a large surface area.  The cerebrum also includes:

Sensory areas : To receive the messages.

Association areas : These areas integrate the incoming sensory information. It also forms a connection between sensory and motor areas.

Motor areas : This area is responsible for the action of the voluntary muscles.

The cerebrum is responsible for thinking, intelligence,  consciousness and memory. It is also responsible for interpreting touch, hearing and vision.

The thalamus is a small structure, located right above the brain stem responsible for relaying sensory information from the  sense organs .  It is also responsible for transmitting motor information for movement and coordination. Thalamus is found in the limbic system within the cerebrum. This limbic system is mainly responsible for the formation of new memories and storing past experiences.

The hypothalamus is a small and essential part of the brain, located precisely below the thalamus. It is considered the primary region of the brain, as it is involved in the following functions:

The tectum is a small portion of the brain, specifically the dorsal part of the midbrain. It serves as a relay centre for the sensory information from the ears to the cerebrum. It also controls the reflex movements of the head, eye and neck muscles. It provides a passage for the different neurons moving in and out of the cerebrum.

Tegmentum is a region within the brainstem. It is a complex structure with various components, which is mainly involved in body movements, sleep, arousal, attention, and different necessary reflexes. It forms the platform for the midbrain and connects with the thalamus, cerebral cortex and the spinal cord.

The cerebellum is the second largest part of the brain, located in the posterior portion of the medulla and pons. The cerebellum and cerebrum are separated by cerebellar tentorium and transverse fissure. Cortex is the outer surface of the cerebellum, and its parallel ridges are called the folia. Apart from this, the cerebellum has the cerebellar peduncles, cerebellar nuclei, anterior and posterior lobes. The cerebellum consists of two hemispheres, the outer grey cortex and the inner white medulla.  It is mainly responsible for coordinating and maintaining the body balance during walking, running, riding, swimming, and precision control of the voluntary movements. The main functions of the cerebellum include:

The medulla oblongata is a small structure present in the lowest region of the brain. It mainly controls the body’s autonomic functions such as heartbeat, breathing, and digestion. It plays a primary role in connecting the spinal cord, pons and the cerebral cortex. Also, it helps us in maintaining our posture and controlling our reflexes.

The pons is the primary structure of the brain stem present between the midbrain and medulla oblongata. It serves as a relay signals between the lower cerebellum, spinal cord, the midbrain, cerebrum and other higher parts of the brain. The main functions of the pons include:

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