| The spinal cord is well-protected by the vertebral column, which extends from the skull to the coccyx, enclosing the entire cord. The vertebral column comprises 33 vertebrae: 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 sacral vertebrae, and 4 coccygeal vertebrae. In adults, the 5 sacral vertebrae are fused to form the sacrum and the 4 coccygeal vertebrae are fused to form the coccyx. The vertebrae are separated by tough fibrocartilage intervertebral discs that make up about one-fourth of the length of the vertebral column. While the structure of the vertebrae varies from one region to another, the spinal cord runs through the vertebral foramen in each vertebra. The vertebral foramen is bordered anteriorly by the vertebral body, laterally by the pedicles and posteriorly by the laminae. Thus, the spinal cord is entirely protected by bone. Nerves enter and exit the spinal cord through intervertebral foramina, which are enclosed by the inferior vertebral notch on the superior vertebra and the superior vertebral notch on the inferior vertebra. |
