Spinal cord and intervertebral disc

Abstract

The spinal cord is a part of the central nervous system (CNS) that extends longitudinally with its surrounding meninges within the vertebral canal down to the space between the first and second lumbar vertebrae. Its morphology is a tubular cord made up of nervous tissue and support cells. Cord includes 31 segments (12 thoracic segments, 5 lumbar segments, 5 sacral segments, and 1 coccygeal segment), which gives 31 pair of spinal nerves to the trunk and limb. It controls the voluntary muscles of the limbs and trunk, receives sensory information from these regions, and controls the viscera and blood vessels of the thorax, abdomen, and pelvis. Intervertebral disc is a highly specialized and organized tissue including three components (Nucleus pulposus, annulus fibrosus, cartilaginous endplates). Each disc forms a fibrocartilaginous joint that provides flexibility and allows bending, flexion, and torsion of the vertebrae. There are a total of 23 discs in the human spine (6 in the cervical region, 12 in the thoracic region, and 5 in the lumbar region) that are located between vertebral bodies. Intervertebral discs have important roles; (1) protecting the spinal cord and nerve roots, (2) maintaining cervical and lumbar lordosis, and (3) absorbing energy and transmitting loads through the spinal column.