Extraneural blood supply can be conpressed leading to interrupted signal firing along the nerve. A peripheral nerver distribution such as the lateral femoral cutaneous nerve will give a more specifc dermatomal region than the dermatomes from the lumbar spinal nerves.

I suppose nociceptor input is not an on-off phenomenom (?spelling). e.g. phantom limb pain in amputees. Rather is must be a relative input that is interrputed in either direction may cause the brain to perceive pain. Hence disruption along the flow of activity, rather than the receptor itself, would still result in the brain perceiving pain.? any more ideas