The valve body includes {TAIL ~ an opening} in one side thereof which forms a seal around a catheter enclosed within {HEAD ~ the cannula} 
The valve body includes { TAIL ~ an opening } in one side thereof which forms a seal around a catheter enclosed within { HEAD ~ the cannula }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD