Spinal cord and vertebral column
What is the spinal cord?
The spinal cord, located within the vertebral column, is a soft cylindrical structure made up of highly organised nervous tissue. Extending downward, as a continuation of the brain, the spinal cord is the main pathway of communication between the brain and the rest of the body. It is a delicate structure protected by the vertebrae and their associated ligaments and muscles, the spinal meninges and the cerebrospinal fluid (CSF).
In adults the spinal cord is approximately 42 to 45 cm in length and extends from the foramen magnum in the occipital bone in the skull to the 2nd lumbar vertebral level (L2). However, the tapering end of the cord may terminate as high as the 12th thoracic vertebral level (T12) or as low as the 3rd lumbar vertebral level (L3).
Thirty-one pairs of spinal nerves enter and exit from the spinal cord throughout its length, passing through small openings between each vertebra. There are 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves and one pair of coccygeal nerves.
Nerves of the spinal cord are grouped or bundled so that related types of nerve fibres run together. Motor nerves, nerves that transmit information to muscles and stimulate movement, are anatomically positioned toward the front of the body. Sensory nerves, nerves that transmit information to the brain about sensations such as touch, position, pain, heat and cold are located toward the rear or posterior of the body.
What is the vertebral column?
The vertebral column in an adult typically consists of 33 vertebrae arranged in 5 regions: 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae and 4 fused coccyx (coccygeal) vertebrae.
In adults the vertebral column is approximately 72 to 75 cm in length and serves to:
- protect the spinal cord and spinal nerves;
- support the weight of the body;
- provide a partly rigid and flexible axis for the body and a pivot point for the head;
- play an important role in posture and motion (movement from one place to another).
Last Reviewed: 28 January 2003
