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