{TAIL ~ A flexible, closed end sheath} is first inserted in {HEAD ~ the body} in a known way 
{ TAIL ~ A flexible , closed end sheath } is first inserted in { HEAD ~ the body } in a known way
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH