Question #21
With regards the intervertebral discs, which of the following is true?
The intervertebral discs are made up of a fibrocartilaginous outer shell - the annulus fibrosis, and a hydrophilic inner core - the nucleus pulposus (a remnant of the notochord).
The hydrophilic core draws water in ensuring the structure is tense.
The annulus fibrosis thins with age and the tense nucleus pulposus may burst through the outer shell (like the jam coming out of a donut). This is known as a prolapsed disc, or slipped disc.
In the cervical and lumbar spine the intervertebral disc makes up the anterior border of the intervertebral foramina. A prolapsed here may cause compression on the spinal nerve roots as they emerge from the spinal cord and mass through the intervertebral foramina. This will result in pain, numbness and weakness in the distribution of that nerve root.
If the disc prolapses centrally this can compress the spinal cord.
Since disc prolapse most commonly occurs in the lumbar region (below the end of the spinal cord) this causes compression on the cauda equina. The result may be bilateral numbness, weakness, pain and loss of control of bladder and/or bowel function. This is known as cauda equina syndrome and is a medical emergency. If these patients are not investigated and treated promptly they may become permanently paralysed.