Why does L5 get compressed with a L4-L5 disk herniation? Because it compresses the nerve exiting below (nerve exits between L5-S1 vertebrae).
Why does that happen?
I guess, its because of cauda equina. The root at the same level, like L4 in L4/L5 herniation, is more lateral and is exiting, but L5 is at the spot where disc herniates (postero-laterally). Is that correct?