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