This causes the blade attached to the syringe to lie almost in line with the walls of the syringe itself .
Walls are used when the blade needs to get very close to parallel with the skin ( when injecting into a surface vein or artery for example ) .
This causes the blade attached to the syringe to lie almost in line with the walls of the syringe itself and they are used when the blade needs to get very close to parallel with the skin ( when injecting into a surface vein or artery for example ) .