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The Spinal Cord

Home
Table of Contents
Introduction
The Lungs
The Trachea
The Testes
The Submaxillary Gland
The Liver
The Stomach and Duodenum
The Blood
The Arteries and Veins
The Adipose Tissue
The Skin
The Pituitary Gland
The Pancreas
The Thyroid
The Kidney
The Spinal Cord
The Cerebellum
The Elastic Cartilage
The Bone
The Smooth Muscle
The Striated Muscle
Conclusion
Bibliography

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The spinal cord is the long extension of the brain that is attached below the medulla oblongata, and extends down the back. As the brain is encased in the skull, the spinal cord is encased by the vertebral column, a series of irregular hollow bones called vertebrae.

 

The spinal cord’s purpose is to relay signals from the brain to other regions of the body, by connecting to nerves that branch off into the rest of the body. The spinal cord does not end at the lower back, as many believe; instead, it ends right below the ribs, and branches off into a bundle of nerves called the cauda equina, which remains enclosed within the vertebral column.

 

The spinal cord itself can be divided into regions; an area of gray matter, and an area of white matter, and branches off into the spinal nerves.

 

The dorsal root of the spinal cord contains the interneurons, which relays the messages between the sensory neurons, which are found in the dorsal root ganglion, and the motor neurons, which are found within the ventral root.

 

The white matter of the spinal cord contains neurons that run vertically along the spinal cord sending sensory and motor signals to and from the brain, or to higher areas of the cord.

 

The spinal cord is also responsible for the co-ordination of the reflex arc. The body depends on involuntary reflexes in order to keep itself protected, and if these reflexes had to travel to the brain in order to be initiated, they would be much slower.

 

The spinal cord acts as the intermediary for the reflex arc; sensory neurons sense a change and potential danger in the environment, and sends messages to the interneurons in the spinal cord, where the data is interpreted. The interneurons than sends a message to the motor neurons to signal the movement of a certain body part in order to keep tissues safe from danger. The motor neuron fires, and the muscle that moves the appendage is contracted, causing movement. A perfect example of the reflex arc is the reflex that causes one to move their hand away from the presence of a hot stove.

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THE WONDERS OF THE HUMAN BODY!