From WebMD: "Piriformis syndrome is an uncommon neuromuscular disorder that is caused when the piriformis muscle compresses the sciatic nerve." http://www.dralexjimenez.com/causes-of-piriformis-syndrome/
Your nerve system is an extensive network that channels nerve impulses from your brain to virtually every cell that makes up your body. This chart shows some of the integral relationships between the spine, nervous system and the body.
Tibialis Posterior trigger point diagram, pain patterns and related medical symptoms. The myofascial pain pattern has pain locations that are displayed in red and associated trigger points shown as Xs.