The obturator retracts as the needle is penetrated through skin, and extends forwardly as soon as {HEAD ~ the needle} enters {TAIL ~ the patients body}, thus helping to protect the patient against accidental injury from the needle 
enters
The obturator retracts as the needle is penetrated through skin , and extends forwardly as soon as { HEAD ~ the needle } enters { TAIL ~ the patients body } , thus helping to protect the patient against accidental injury from the needle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH