{TAIL ~ An anchoring means} may optionally be provided at {HEAD ~ the distal end} of the expansion member 
{ TAIL ~ An anchoring means } may optionally be provided at { HEAD ~ the distal end } of the expansion member
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH