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Spinal Cord


STRUCTURE

The spinal cord does not run the entire length of the vertebral column and the former is shorter than the latter. It is not uniform in width throughout its length and is enlarged at the cervical and lumbar regions (these areas give extensions to the limbs). The spinal cord like the brain has meninges around it.

When seen in a cross section, spinal cord has an outer white matter and an inner gray matter. White matter has nerve fibers whereas gray matter is composed of cell bodies of neurons (nerve cells). All this pattern of gray and white matter looks like a butterfly. It is elliptical in shape.

 

SEGMENTS

The spinal cord is divided into 30 segments of spinal nerves. These are:

Region

Number of vertebral column segments

Number of spinal cord segments

Cervical

7

8 pairs

Thoracic

12

12 pairs

Lumbar

5

5 pairs

Sacral

5

5 pairs

Coccygeal

3

*1 pair

*The coccygeal nerves join to form a single pair, exiting the spinal cord through the sacral hiatus.

 

FUNCTIONS

 

The spinal cord mainly functions as a pathway for the transmission of nerve impulses from the brain to all the parts of the body. However it can also work on its own, independent of the brain. It has three major functions:

  • It functions as a circuit for relaying motor commands (movements, etc.) which travel away from the cord.

  • It relays sensory information from the periphery, which travel towards the cord.

  • It acts as a center for producing certain reflexes.

 

CLINICAL IMPORTANCE

Injuries to the spinal cord are caused by trauma such as stretching, bruising, pressure, etc. These injuries lead to loss of sensation and/or motor functions of the concerned area of the body or body part. This happens because of the compression and damage to the spinal cord by the bones of the vertebral column.

The cervical and lumbar regions are the most common areas to be damaged by spinal injury. These injuries affect the limbs.

The non-traumatic injuries of the spinal cord may be caused by diseases like polio, spina bifida, transverse myelitis, tumor of the spinal cord, etc.

 



STRUCTURE

The spinal cord does not run the entire length of the vertebral column and the former is shorter than the latter. It is not uniform in width throughout its length and is enlarged at the cervical and lumbar regions (these areas give extensions to the limbs). The spinal cord like the brain has meninges around it.

When seen in a cross section, spinal cord has an outer white matter and an inner gray matter. White matter has nerve fibers whereas gray matter is composed of cell bodies of neurons (nerve cells). All this pattern of gray and white matter looks like a butterfly. It is elliptical in shape.

 

SEGMENTS

The spinal cord is divided into 30 segments of spinal nerves. These are:

Region

Number of vertebral column segments

Number of spinal cord segments

Cervical

7

8 pairs

Thoracic

12

12 pairs

Lumbar

5

5 pairs

Sacral

5

5 pairs

Coccygeal

3

*1 pair

*The coccygeal nerves join to form a single pair, exiting the spinal cord through the sacral hiatus.

 

FUNCTIONS

 

The spinal cord mainly functions as a pathway for the transmission of nerve impulses from the brain to all the parts of the body. However it can also work on its own, independent of the brain. It has three major functions:

  • It functions as a circuit for relaying motor commands (movements, etc.) which travel away from the cord.

  • It relays sensory information from the periphery, which travel towards the cord.

  • It acts as a center for producing certain reflexes.

 

CLINICAL IMPORTANCE

Injuries to the spinal cord are caused by trauma such as stretching, bruising, pressure, etc. These injuries lead to loss of sensation and/or motor functions of the concerned area of the body or body part. This happens because of the compression and damage to the spinal cord by the bones of the vertebral column.

The cervical and lumbar regions are the most common areas to be damaged by spinal injury. These injuries affect the limbs.

The non-traumatic injuries of the spinal cord may be caused by diseases like polio, spina bifida, transverse myelitis, tumor of the spinal cord, etc.

 

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