While I don't have an answer for you, I reckon Blaise Pascal is generally
credited with inventing the syringe per se.  I don't know much about the
needles; however, I do know of a southwest {*filter*}ia country doctor who
some thrity or more years ago invented, patented, used, and sold a syringe/
hypodermic needle combination that retracted, injected with the flip of a
trigger, then retracted, giving a near-painless injection.  The fellow was
Dr. Daniel Gabriel, and it was termed the Gabriel--somebody else syringe.
Did you come across that one.  (Plastic, disposable syringes came onto the
market about that time and his product went by the wayside, to my knowledge.)