A transition or {HEAD ~ tapered portion} 50 extends from the portion 48 to {TAIL ~ an enlarged portion}, shown as a spherical cap 52 
extends to
A transition or { HEAD ~ tapered portion } 50 extends from the portion 48 to { TAIL ~ an enlarged portion } , shown as a spherical cap 52
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH