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