The sciatic nerve is made up of many smaller nerves that exit your low back.  The sciatic nerve innervates many of the muscles and skin of the legs and feet.  Sciatica is caused by compression on the sciatic nerve causing pain to radiate down your leg along the nerve itself.  Determining what structure is pressing on the nerve is vital in getting rid of sciatic pain.

Most commonly the opening (the intervertebral foramen) where the nerve exits the spinal column gets smaller causing the compression.  This can be a result of your discs (intervertebral discs) losing height due to dehydration, the result of a bulging/ herniated disc, or even bone spurs.  A less common site of compression is behind the hip on the affected side.

In most cases chiropractic care is recommended for sciatica prior to seeking a surgical consult, as the vast majority of sciatica cases can be resolved without surgery.

Any time you experience numbness or tingling in your extremities it is advised to be assessed by a trained medical professional.

https://pubmed.ncbi.nlm.nih.gov/29939685/