Parts of Central Nervous System

Introduction

The nervous system is responsible for controlling all the body functions and responding to the external environment. In Humans Nervous system is the most advanced among all other animals and is composed of two main parts or types i.e. the Central Nervous System (CNS) and the Peripheral Nervous System ( SNP). The two main parts of the Central Nervous System are the Brain and spinal cord. Stay connected to learn more about these parts and their functioning.

 

  • The Peripheral Nervous System is made up of all the nerves that start from the CNS and extend throughout the body.
  • The Central Nervous System is formed by the brain and spinal cord.

Summary of Main Parts Of CNS 

overview of brain parts
overview of brain parts (source Wikipedia)

Central nervous system

Definition: The  Central nervous system or CNS is protected by the skull, the spine and the membranes called meninges. It is formed by the brain and spinal cord, composed of millions of cells connected to each other i.e. neurons. CNS is called so, because of its central role in receiving and interpreting informations from all over the body and giving instructions to different body organs. so it controls all body responses and forms a communication link between all body organs.

If you want to know what are the functions of the Central Nervous System, we recommend you continue reading this article.

Two Main Parts of the Central Nervous System

Obviously, these are the Brain & Spinal cord which are protected by the skull and vertebral column respectively.

Parts and functions of the brain

In animals, all activities of life are under the control of the brain.

  •  The brain is located inside a bony skull (part of the skull).
  •  Inside the skull, the brain is covered with three layers called meninges.
  •  The meninges protect the brain and also supply nutrients and oxygen to the brain tissues via their capillaries.
  • The brain contains fluid-filled ventricles that are continuous with the central canal of the spinal cord. The fluid in the ventricles and the central canal is called cerebrospinal fluid (CSF).

Divisions of the brain

There are three main regions in the brain of humans and other vertebrates. These are follows

A) Forebrain

In humans, the forebrain is the largest and most developed. Its parts are follow.

(i) Thalamus

  • The thalamus lies just below the brain. It serves as a relay center between different parts of the brain and spinal cord.
  •  It also receives sensory impulses by other parts of the CNS and modifies them before they travel to the brain.
  • The thalamus is also involved in pain perception and consciousness (sleep and wakefulness).

(ii) Hypothalamus

The hypothalamus lies above the midbrain and just below the thalamus. In humans, it is about the size of an almond.

  • The main function of the hypothalamus is to regulate the balance of our body and basic needs such as, for example, the intake of food, drink, and the instinct for reproduction.
  • The hypothalamus connects the nervous system to the endocrine system.
  • It controls the secretions of the pituitary gland.
    Feelings such as rage, pain, pleasure, and grief are controlled by the hypothalamus.

There is also the epithalamus, which belongs to the limbic system, related to emotions and intuition. It also contains the pineal gland, which regulates the states of sleep and wakefulness.

(iii)Cerebrum

The cerebrum is the largest part of the forebrain. It is divided into two cerebral hemispheres. It controls skeletal muscles, thought, intelligence and emotions.
The anterior parts of the cerebral hemispheres are called olfactory bulbs. These receive impulses from the olfactory nerves and create the sensation of smell.

The upper layer of the cerebral hemispheres is called the cerebral cortex. It is made up of gray matter. Beneath this layer is white matter.

The gray matter of the nervous system consists of cell bodies and unmyelinated axons while the white matter consists of myelinated axons.

Lobes of the brain of the Forebrain

  • The frontal lobe controls voluntary movements, motor functions, enables conscious control of skeletal muscles,  speech, and is related to the ability to plan, with intelligence and personality.
  • The occipital lobe receives and analyzes visual information
  • The temporal lobe deals with hearing and smell and integrates auditory information, & emotions.
  • The parietal lobe, Receives impulses from the skin and integrates the tactile information of the whole body.

The hippocampus is a structure present deep in the brain. It controls the formation of new memories. People with damaged hippocampus cannot remember things that happened after the damage but can remember things that happened before the damage

B) Midbrain

The midbrain lies between the hindbrain and the forebrain and connects the two.  It receives sensory information and sends it to the appropriate part of the forebrain. The midbrain also controls certain auditory reflexes and posture.

C) Hindbrain:

It consists of three main parts, i.e. Medulla oblongata, Cerebellum, and Pons.

(i) The Medulla oblongata

The medulla oblongata is found at the top of the spinal cord. It controls breathing, heart rate, and blood pressure.

  • It also regulates vital functions such as respiratory function, heartbeat. It also controls many reflexes like vomiting, coughing, sneezing, hiccups, and swallowing.
  • The information that passes between the spinal cord and the rest of the brain passes through the spinal cord.

(ii) The Cerebellum

The cerebellum is behind the medulla. It coordinates muscle movements.

(iii) Pons

Pons is present above the medulla. It helps the spinal cord control breathing. It also serves as a link between the cerebellum and the spinal cord.

The medulla, pons, and midbrain connect the rest of the brain to the spinal cord. They are collectively referred to as the brainstem

Parts and function of the spinal cord.

Definition: The spinal cord is a tubular bundle of nerves that is an extension of the medulla oblongata. It starts from the brainstem and extends to the lower back. It is also covered with meninges. The spinal cord is protected by the vertebral column.

  •  The outer region of the spinal cord is made up of white matter (containing myelinated axons).
  • The central region is butterfly-shaped and surrounds the central channel. It is made up of gray matter (containing the cell bodies of neurons).
  •  31 pairs of spinal nerves arise along the spinal cord. They are “mixed” nerves because each contains axons of sensory and motor neurons.

Spinal Nerve Roots: Spinal nerves have two roots

  •  The dorsal root contains sensory axons and a ganglion where the cell bodies are located.
  • The ventral root contains the axons of the moton

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