Central Nervous System: Structure, Function, Brain & Spinal Cord

Central Nervous System: Structure, Function, Brain & Spinal Cord

Central Nervous System

The central nervous system CNS consists/comprises of the brain and spinal cord, both are protected/safeguarded in three ways:

  • Cranium: Cranium, which is part of the skull, protects the brain and neural arches.
  • Vertebrae: The vertebrae of the vertebral column safeguards the spinal cord.
  • Meninges: Beneath the uranium, triple layer of meninges protects the brain and spinal cord.
  • Cerebro-spinal fluid (CSF): Between the layer/sheet of meninges, the cerebrospinal fluid (CSF) is present. It is similar/indistinguishable in composition to blood plasma.

It bathes the neurons of the brain and spinal cord and cushions against the bumps and jolts.
Central canal and ventricles: Both brain and spinal cord are empty/hollow. The spinal cord has a central canal and the brain has many cavities/spaces (ventricles) filled by cerebrospinal fluid (CSF).


The brain can be divided into parts:

  1. Forebrain. . . ,
  2. Midbrain. . . ,
  3. Hindbrain. . . !


The forebrain is divided into three functional parts:

  1. Thalamus,...
  2. The Limbic system,...
  3. The Cerebrum,.


Thalamus plays a vital/important role in the transmission of sensory information to the limbic system and cerebrum. The information includes sensory input from auditory and visual pathways/passageways, from the skin and from within the body.

The Limbic system

Location: The limbic system is located/exists in an arc between the thalamus and cerebrum.
Parts of Limbic system:
The limbic system consists of

  • Hypothalamus,... . . . 
  • Amygdala, ...
  • The hippocampus as well as,...
  • Nearby regions of the cerebrum,. . . . 


The hypothalamus through its hormone production and neural connections act as a major coordinating center controlling body temperature, hunger the menstrual cycle in human females, water balance, the sleep-wake cycle, etc.


In the amygdala, the cluster of neurons produces the sensation of pleasure, punishment or sexual arousal when stimulated. It is also involved in the feelings/desires of fear and rage.


The hippocampus plays a significant role in the generation/formation of long-term memory, and thus is required for learning.

Functions of Hippocampus

The limbic system works together to produce our most basic and primitive emotions, drives, and behaviors, including fear, rage, tranquility, hunger, thirst, pleasure and sexual responses.
The portion of the limbic system is also very significant in the production/formation of memories.


Largest Part: Cerebrum is the largest part of the brain.
Cerebral hemispheres: Cerebrum is halved into two halves, both of these halves are called cerebral hemispheres.
Corpus Callosum: Cerebral hemispheres communicate with each other by means of an elongated band of axons, called corpus callosum. Tens of billions of neurons are packed into this part/portion.
Cerebral Cortex: The outer region of the cerebrum is the cerebral cortex.
Convolutions: Cerebral cortex forms folds called convolutions, which greatly increase its surface area.

Functions of the cerebral cortex

  • Cerebral cortex receives sensory information, processes it, stores some in memory for future use, direct voluntary movements, and are responsible for the peony understood process that we call thinking.
  • The cerebral cortex contains primary sensory areas where signals originate in sensory organs such as eyes and ears are received and converted into subjective impressions, such as light and sound. Nearby association areas illuminate this information.
  • The cerebral cortex is also involved in speech and also receives interprets sensations of touch from all parts of the body.
  • The cerebral cortex is also a center for sending impulses to voluntary muscles, controlling movements.
  • The cerebral cortex is also involved in intelligence, thoughts & reasoning, and judgments.
 The left cerebral hemisphere manages/controls the right side of the body, and the right cerebral hemisphere controls the left side of-of the body.


Reduced: Midbrain reduced in humans, and auditory Relay Centre: It contains auditory relay center.
Centre for Reflex Eye Movement: It also contains center that controls reflex movements of eyes.
Reticular Formation: Midbrain contains reticular formation, which is a relay center connecting/joining hindbrain with the forebrain. The reticular formation is very important in screening the input information before they reach higher brain centers.

Hind Brain

Hindbrain contains the

  • medulla, ..
  • pons, ..
  • and cerebellum. ..


The medulla controls severals automatic functions, such as breathing, heart rate, blood pressure, and swallowing.


Certain some neurons in the pons, located above the medulla, appear to influence transitions between sleep and wakefulness, and the rate and pattern of breathing.


  • The cerebellum is very significant/important in coordinating movements of the body.
  • The cerebellum guides, smooth and accurate motions and maintain body position.
  • The cerebellum is also involved relates in the learning and memory storage for behaviors.
  • It is best well developed in birds, which engage in the complex activity of flight.

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