In operation as shown in FIG 4, {HEAD ~ a hollow needle} subcutaneously enters {TAIL ~ the blood vessel} 
In operation as shown in FIG 4 , { HEAD ~ a hollow needle } subcutaneously enters { TAIL ~ the blood vessel }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL