system
Given the following post, respond as if you're commenting on Reddit:
human
Why are spinal discs so prone to hernias?

I'm a 1st year med student, studying the lumbar region in anatomy, we barely brush on the subject and the professor wasn't able to give me the answer I was looking for.

So, throughout the millions of years of evolution, how come the spinal discs are STILL so prone to hernias and bulges? I mean, it was enough for me to pick up weights in an incorrect way to herniate my L5S1 (CT+MRI approved) as well as billion of others who suffer from a similar condition.
gpt
To add to other comments:

L5/S1 is particularly prone to injury because the disc is situated along a steep slope just above the pelvis, and so it carries the weight of the torso not squarely on its face like all the other discs, but at a fairly steep grade. Additionally (and this is true throughout the spine), the ligament that covers the rear of the disc (the posterior longitudinal ligament) is hourglass-shaped instead of broad and flat like the one in front. This creates a weak spot in the ligamentous "wrapping" of the disc on either side, at roughly 5 o'clock and 7 o'clock, which is a convenient spot for the disc nucleus to herniate should an injury occur. It just so happens that the nerves are at 5 and 7 o'clock, which is why disc herniations so frequently result in arm or leg pain.