Spinal Cord
Spinal cord is a collection of nervous tissue and supporting cells that is an extension of the brain running downwards. It is in the form of a tube like structure starting at the base of the skull and ending at the level of the space between the first and second lumbar vertebrae. It is about 45 cm in length in men and 43 cm in women. The spinal cord is a delicate structure protected by the bones enclosing it, the vertebral column.
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Spinal Cord
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.
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. 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.
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
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CLINICAL IMPORTANCE
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