Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 93. Spinal Cord Disorders

Topics: Introduction | Accident-Related Injuries | Spinal Cord Compression | Cervical Spondylosis | Spinal Hematoma | Syrinx | Hereditary Spastic Paraparesis | Acute Transverse Myelitis | Blockage of the Blood Supply | Subacute Combined Degeneration of the Spinal Cord

Introduction

The spinal cord is the main pathway of communication between the brain and the rest of the body. It is a long, fragile, tubelike structure that extends downward from the base of the brain. The cord is protected by the back bones (vertebrae) of the spine (spinal column), which are separated and cushioned by disks made of cartilage.

See the figure Which Area of the Spine Is Damaged?

Along the length of the spinal cord, 31 pairs of spinal nerves emerge through spaces between the vertebrae. The spinal nerves connect with nerves throughout the body. Each spinal nerve has two nerve roots (except the first, which has no sensory root). The root in the front, the motor root, transmits impulses from the spinal cord to the muscles. The root in the back, the sensory root, carries sensory information (about touch, position, pain, and temperature) from the body to the spinal cord.

The spinal cord is highly organized (see Section 6, Chapter 76); nerve pathways with similar functions are grouped together. The motor nerves, which transmit information to muscles and thus stimulate movement, are grouped together, as are the sensory nerves, which transmit sensory information to the brain. The motor and sensory nerves of the spinal cord connect with the motor and sensory roots of the spinal nerves, respectively.

See the figure Dermatomes.

Because of the function and organization of the spinal cord, damage to the cord can produce various patterns of symptoms, such as numbness, weakness, loss of sensation, loss of bowel and bladder function, and paralysis, as well as back pain. These patterns enable doctors to determine the location (level) of spinal cord damage.

Some spinal cord disorders originate outside the cord. They include injuries, infections, blockage of the blood supply, and compression. The spinal cord may be compressed by bone (as in cervical spondylosis or a fracture), an accumulation of blood (hematoma), a tumor, a localized collection of pus (abscess), or a ruptured or herniated disk. Other spinal cord disorders originate within the cord. They include fluid-filled cavities (syrinxes), acute transverse myelitis, tumors, abscesses, bleeding (hemorrhage), and multiple sclerosis.