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