Intervertebral disc

1. What are the three major components of a disc?
2. What is the vascular supply of a disc?
3. What is the function of a disc?
4. What are the effects of aging on a disc?

Answers:
1. The nucleus pulposus is a viscous gel mixture of type II collagen inside the disc, the annulus fibrosus is type I collagen that encases the nucleus pulposus (weak for torsional stresses), the vertebral endplate is the cartilaginous covering of the vertebral body apophysis, forming the top and bottom of the disc.
2. Avascular.
3. Vertebral body motion, weightbearing.
4. Decrease in nuclear water content, ratio of chondroitin-keratin, proteoglycan molecular wt. Increase in fibrous tissue, cartilage cells, amorphous tissue.