gas engine: an internal-combustion engine similar to a gasoline engine but using natural gas instead of gasoline vapor
internal-combustion engine: a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine
sciatic nerve: arises from the sacral plexus and passes about halfway down the thigh where it divides into the common peroneal and tibial nerves