The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. The brain and spinal cord together make up the central nervous system (CNS).
The spinal cord starts at the medulla oblongata of the brainstem and ends at the lumbar area of the vertebral column. The spinal cord as well as the brain make up the central nervous system (CNS).
Three tissue layers known as meninges surround and protect the brain and spinal cord. The outermost protective layer is called the dura mater. The epidural space, which is made up of a network of blood vessels as well as adipose tissue, occurs between the surrounding vertebrate bone and the dura mater. The middle protective layer resembles spider webs and therefore is known as the arachnoid mater. The subarachnoid space contains cerebrospinal fluid, and lies in between the pia and arachnoid mater. The pia mater is the delicate, innermost protective layer.
The human spine has 31 segments which include:
- 8 cervical segments
- 12 thoracic segments
- 5 lumbar segments
- 5 sacral segments
- 1 cocygeal segment