The funnel shaped occlusion balloon seals {HEAD ~ the walls} of {TAIL ~ the vessel} to establish retrograde flow of blood 
of
The funnel shaped occlusion balloon seals { HEAD ~ the walls } of { TAIL ~ the vessel } to establish retrograde flow of blood
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH