{HEAD ~ said main portion} and tubular portion having an inner surface and {TAIL ~ a generally arcuate shaped outer surface} 
having
{ HEAD ~ said main portion } and tubular portion having an inner surface and { TAIL ~ a generally arcuate shaped outer surface }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL