The Spinal Cord

The spinal cord is an extension of the brain and is surrounded by the vertebral bodies that form the spinal column (see Multimedia File 3). The central structures of the spinal cord are made up of gray matter (nerve cell bodies), and the external or surrounding tissues are made up of white matter.

Within the spinal cord are 30 segments that belong to 4 sections (cervical, thoracic, lumbar, sacral), based on their location: 

• Eight cervical segments: These transmit signals from or to areas of the head, neck, shoulders, arms, and hands.  



• Twelve thoracic segments: These transmit signals from or to part of the arms and the anterior and posterior chest and abdominal areas. 



• Five lumbar segments: These transmit signals from or to the legs and feet and some pelvic organs. 



• Five sacral segments: These transmit signals from or to the lower back and buttocks, pelvic organs and genital areas, and some areas in the legs and feet. 



• A coccygeal remnant is located at the bottom of the spinal cord.