The annular protrusion further has a distal end with {HEAD ~ an internal groove} with {TAIL ~ a base portion}, a front wall and a rear wall 
with
The annular protrusion further has a distal end with { HEAD ~ an internal groove } with { TAIL ~ a base portion } , a front wall and a rear wall
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH