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An intervertebral disc (British English), also spelled intervertebral disk (American English), lies between adjacent vertebrae in the vertebral column.Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to hold the vertebrae together, and to function as a shock absorber for the spine.
The spinal cord (and brain) are protected by three layers of tissue or membranes called meninges, that surround the canal. The dura mater is the outermost layer, and it forms a tough protective coating. Between the dura mater and the surrounding bone of the vertebrae is a space called the epidural space.
In the spinal canal, the periosteal layer adheres to the inner surface of the spinal canal which is formed by the bodies of vertebrae. The meningeal layer lays over the spinal arachnoid mater. [2] Between the vertebrae and the dural sheath is the spinal epidural space.
The lumbar cistern is part of the subarachnoid space.It is the space within the thecal sac which extends from below the end of the spinal cord (the conus medularis), typically at the level of the first to second lumbar vertebrae down to tapering of the dura at the level of the second sacral vertebra.
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
Spinal stenosis is a narrowing of the canal which can occur in any region of the spine and can be caused by a number of factors. It may result in cervical myelopathy [4] if the narrowed canal impinges on the spinal cord itself. Spinal canal endoscopy can be used to investigate the epidural space, and is an important spinal diagnostic technique ...
The dura mater covering the spinal cord is known as the dural sac or thecal sac, and only has one layer (the meningeal layer) unlike cranial dura mater. The potential space between these two layers is known as the epidural space, [5] which can accumulate blood in the case of traumatic laceration to the meningeal arteries.
The discs between these vertebrae create a natural lumbar lordosis (a spinal curvature that is concave posteriorly). [citation needed] This is due to the difference in thickness between the front and back parts of the intervertebral discs. The lumbar vertebrae are located between the ribcage and the pelvis and are the largest of the vertebrae.