Thus, a gas may be delivered from a gas source through the gas tubing, swivel coupling, and cannula to {HEAD ~ a patient} without tangling or twisting {TAIL ~ the tubing} 
without tangling
Thus , a gas may be delivered from a gas source through the gas tubing , swivel coupling , and cannula to { HEAD ~ a patient } without tangling or twisting { TAIL ~ the tubing }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL