Spinal Cord Anatomy

Your brain and spinal cord anatomy make up the central nervous system, and the peripheral nervous system is made up of the nerves that run from the spine and supply the rest of your body.

The human spinal cord is a thick cable of highly specialised nervous tissue. It starts at the brain and ends in the spinal canal at about the 2nd lumbar level. The function of the spinal cord is to pass nerve impulses from the brain and back again from the tissues.

When looked at in cross section or sliced sideways spinal cord anatomy shows two distinct areas. A darker grey central area which is butterfly shaped, this is surrounded by a whiter area.  The central area contains grey matter, and is made up of the cell bodies of the nerve cells.

Image above courtesy wikimedia - Copyright here

The whiter outer area is made up of myelinated axons. These are whitish in colour as the myelin sheath is a little like an insulator which helps speed up the transmission of nerve impulses. See the diagram below. These axons run up and down the length of the spinal cord.

When you are looking at the butterfly the top two wings are called the dorsal (posterior) horns and the bottom two are called the ventral (anterior) horns. The dorsal horns are very interesting to us as they are responsible for processing sensory information from the body. This is where your nervous system starts interpreting your pain and this area can become over sensitised as I described in this section on pain.

Different parts of the spinal cord transmit different types of nerve impulses so if you have a spinal cord injury the symptoms you will get will depend on which part of the spinal cord is involved. For example the white area between the two dorsal horns at the top consists of tracts that send messages to the brain about pressure, touch and position sense.

Lower back pain rarely involves damage to the spinal cord anatomy, it actually stops much higher up in the back then most people realise. However, changes to the processing of information through the cord are very important in our understanding of back pain as increased sensitivity in this area has been seen in response to chronic pain. This can be instrumental in the cycle of chronic pain described here.

14-Sep-2009

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