basic anatomy nerve root question - medc

[ArchivalUser]

According to Acland anatomy the cervical spinal nerve roots exit through vertebra X and the one ABOVE it. (Example C4 root via foramen formed by C4 and C3 vertebrae).

While the thoracic and lumbar nerve roots exit via vertebra X and the one below it.

Therefore according to this, the L5 nerve root would be compressed by herniation of L5/S1 disk.

According to High Yield gross anatomy, the L5 nerve root would be compressed by L4/L5.

Which one is correct??

[ArchivalUser]

Ok this is hard to explain without a diagram but I will give it a shot.

1. You are correct in that the nerve in teh thoracic and lumbar areas exit below there respective vertebrae in that the L4nerve will exit between L4 and L5. However, keep in mind that a herniated disc is a disc that "slips" backwards into the spinal cord. Therefore, if there is a slippage of of "L4 and L5" in the way that the nucleus pulposis(the substance seperateing the two repsective vertabrea)moves backwards it will hit the L5 nerve because the L4 nerve has already exited. Bottom line is that the herniation affects the nerve that is still in the spinal cord not the one exiting at that junction. THerefore, as you stated the L4 nerve will exit under the L4 vertebrae and be spared in a herniation of L4 and L5 but the next nerve L5 will be compressed before it can exit between L5 and S1.

Like i said it is hard to explain without a diagram but if i can clear anything up even more just write back...GL

[ArchivalUser]

Oh I see it! the intervertebral foramen where the nerve root exits is slightly above the acutal disk...


thanks a lot xahdum!!!!!!!!!!!!!!!!!!