The human spine consists of 33 vertebrae:
Cervical vertebra (C1-C7)
Thoracic vertebra (T1-T12)
Lumbar vertebra (L1-L5)
coccyx are made up of 9 fused vertebrae
Each vertebra is attached to the one above and below it by ligaments and
muscles. They are separated from the vertebra above and below it by an
Two vertebra and the disc between them make up a
Each vertebra is made up of:
Spinous process: the part of the spine you can feel through your skin
Lamina: The laminae form the walls of the spinal canal has four projections called
superior processes extending from the upper border,one on each side
inferior processes extending from the lower border, one on each side
- Facet joints
Formed by the overlapping of the projections from the lamina. The upper
projection of one lamina (superior articular process) is overlapped by
the lower projection (inferior articular process) of the adjacent vertebra
and together form the facet joint.
There is a facet joint on each side of the spine at every level.
- Intervertebral Disc
The structure that separates two vertebra
Nucleus, the jelly-like center. Under pressure, the nucleus pushes the vertebra apart
Annulus, a fibrous ring that attaches to the vertebrae has high water content
A normal disc is so strong that it can be damaged only by extreme forces.
A normal, healthy disc is one of the best parts of the spine.
An opening between the pedicles of the vertebrae through which nerve roots
exit off the spinal cord.
- Spinal canal
Contains the spinal cord from the brain stem to the upper lumbar spine.
There is no spinal cord in the lower lumbar spine. At the L1 level, the
spinal cord terminates as the conus medullaris.
A bundle of nerves called the
cauda equina (meaning horse's tail) branch off the conus medullaris. These nerve
roots are suspended in the fluid-filled dural sac.