Structure of the Nervous System: Elements that Constitute the Nervous System and its Functions

It is broadly divided into two sections: the CNS and the SNP.

The central nervous system (CNS) is made up of: the brain and the spinal cord .

The peripheral nervous system (PNS) is made up of: the nerves that radiate from the spinal cord to the rest of the body.


The SNP is further divided into:

  • The somatic nervous system: this is responsible for the voluntary control of body movements.
  • The Autonomic Nervous System (ANS) : It is responsible for the unconscious regulation of internal organs, glands, and hormones.

Finally, the SNA is divided into:

  • Sympathetic nervous systems.
  • Parasympathetic nervous systems.

The sympathetic nervous system is generally responsible for holding the body together during times of stress and is well known for mediating the stress response known as the fight or flight response .

The parasympathetic nervous system, on the other hand, is responsible for the stimulation of activities that occur when the body is at rest and in states of low stress, including sexual arousal, digestion , excretion, etc.

Elements that constitute the structure of the nervous system and its functions


The main mass of this structure is the brain, which is divided into the left and right hemispheres. The right hemisphere controls the left side of the body and vice versa.

The right side of the brain seems to be mainly involved in:

  • The spatial orientation.
  • Abstract thoughts.
  • The creativity.
  • The music .
  • Rhythm.
  • Others.

The left side of the brain seems to mainly process:

  • Verbal language.
  • Rational thoughts.

In men, both lobes are approximately the same size, while in women the left hemisphere is slightly larger than the right.

The rhombencephalon

The rhombencephalon is believed to be the oldest part of the nervous system structure and is made up of the cerebellum, pons, and brainstem. The cerebellum is located below the brain, and is primarily a control center for:

  • Movement.
  • Regulation and coordination.
  • Balance and posture.

The brain stem is located just below the cerebellum, and is connected to both the cerebellum and the brain. It is through the brain stem that messages are sent from the brain to the rest of the body, and that the brain receives messages from the rest of the body.

The medulla oblongata is another ancient part of the brain, involved in a wide range of motor and sensory functions.

Finally, the pons is a small area of ​​the rhombencephalon that transmits signals from the forebrain to the cerebellum. It also appears to be involved in sleeping, breathing, swallowing, bladder control, hearing, and facial expressions.

The midbrain

The midbrain is located just above the hindbrain and below the forebrain, just around the center of the brain. It is mainly associated with vision, hearing, motor control, sleep or wake cycles, activation, and temperature regulation.

The forebrain

The forebrain is the largest part of the brain, and is primarily made up of the brain (made up of the temporal lobe, frontal lobe, parietal lobe, and occipital lobe).

The forebrain also contains:

  • The thalamus.
  • The hypothalamus.
  • The pituitary gland.
  • The amygdala.
  • The corpus callosum.
  • The hippocampus.
  • The basal ganglia.

The function of the thalamus includes the transmission of sensations, spatial sense, and motor signals to the cerebral cortex, as well as the regulation of the sleep / wake cycle and alertness.

All sensory systems, other than the olfactory system, transmit information to the thalamus, which is believed to process sensory information and transmit it to other parts of the brain.

The hypothalamus

The main function of the hypothalamus is to link the nervous system to the endocrine system through the pituitary gland. Creates and secretes neurohormones that stimulate or inhibit the secretion of pituitary hormones.

Therefore, the hypothalamus controls body temperature, appetite, fatigue, sleep, and circadian rhythms.

The pituitary gland

The pituitary gland is an endocrine gland that is connected to the hypothalamus.

Secrets hormones that help control:

  • Growth.
  • Blood pressure
  • Uterine Contractions.
  • The functions of the sexual organs.
  • The function of the thyroid gland.
  • Metabolism
  • Temperature regulation, among other things.
The amygdala

The amygdala are small groups of nuclei located within the temporal lobes of the brain. The amygdala plays a major role in the processing and memory of emotional reactions.

The amygdala is thought to be essential in the formation and storage of memories associated with emotional events, such as fear conditioning.

The corpus callosum

The corpus callosum is a set of neural fibers found beneath the cortex that connects the left and right hemispheres of the brain, allowing communication between hemispheres. It is the largest white matter structure in the brain.

The hippocampus

The hippocampus plays an important role in consolidating information from short and long-term memory.

It is also an essential part of spatial orientation. The hippocampus is one of the first parts of the brain to be damaged in Alzheimer’s disease, and damage to the hippocampus leads to memory problems and disorientation.

People with severe damage to the hippocampus sometimes experience anterograde amnesia, the inability to form or retain new memories.

The basal ganglia

The basal ganglia are a group of nuclei located at the base of the forebrain. They are associated with a variety of functions, including procedural learning (habit formation), eye movements, emotions, cognition, and voluntary motor control.

Research suggests that the basal ganglia are the part of the brain that is used when making a decision about which of several possible actions to take at any given time.

It appears that the basal ganglia inhibit several different motor systems, and when the basal ganglia stop that inhibition, those systems can become activated.

This mechanism is influenced by signals from the prefrontal cortex, which plays a key role in executive functioning.


The surface of the brain is known as the cerebral cortex and is made up of six layers of neurons.

It’s very bent and convoluted, and if spread out, it would take up about 2.5 square feet of space. It contains around 10 billion neurons and around 50 trillion synapses.

The folds of the cortex have ridges, called convolutions, and valleys, called furrows. Some of the furrows are very long and pronounced, and these serve as boundaries between the four divisions of the crust known as lobes.

Frontal lobe

The frontal lobe is located at the front of the brain and is responsible for voluntary movement and planning.

It contains most of the dopamine-sensitive neurons in the cerebral cortex. Given that the dopamine system is associated with reward, attention, short-term memory, and planning, it is not surprising that this part of the brain is most involved in decision-making.

At the back of the frontal lobe is an area called the motor cortex. This portion of the brain is designed to control voluntary muscle movement.

The prefrontal lobe

The most forward part of the frontal lobe is known as the prefrontal lobe. This part of the brain seems to be involved in cognitive behavior planning, decision making, personality expression, and moderation of correct social behavior.

In other words, the prefrontal lobe is thought to coordinate thoughts and actions with internal short-term and long-term goals.

It is also believed to be the part of the brain that carries out executive functions, which allow the individual to recognize the future consequences of present actions, choose between good and bad actions, suppress unacceptable responses, and see the differences and similarities between things.

In 1936, neurologists Freeman and Watts created a method of lobotomy known as the Freeman-Watts procedure, which separated the prefrontal lobe from the rest of the brain.

This process was thought to be helpful for people with severe mental disorders, as it seemed to calm them.

However, it also completely removed these people’s ability to make their own decisions in any way, making them generally docile but also extremely mentally disabled in most cases.

The parietal lobe

The parietal lobe is located behind the frontal lobe. The most important portion is known as the somatosensory cortex, and this portion of the brain appears to be responsible for receiving sensory information from the entire body.

The parietal lobe integrates sensory information, particularly in relation to spatial sense and navigation. It also maps visually perceived objects to body coordinate positions.

The temporal lobes

The temporal lobe is located on both sides of the brain and is involved in auditory perception. It is also very important in speech and vision language processing.

The temporal lobe also contains the hippocampus which, as noted above, is essential in the formation of long-term memory.

In the left temporal lobe there is a portion of the cortex known as Wernicke’s area that is essential for understanding written and spoken language.

The occipital lobe

The occipital lobe is located at the back of the brain and is the visual processing center of the brain. It is also the part of the brain from which dreams seem to originate.