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