Hypodermic injection is a method for administering drugs under the skin. Equipment for the injection includes a syringe (tube with a plunger attached) and a hollow needle. The needle has a sharp point that permits it to easily go into the skin. The doctor attaches the needle to the syringe barrel, puts the liquid medicine in the syringe, and inserts the needle into the patient’s skin. Then, the doctor presses on the plunger to force the medicine through the needle. The hollow needle was invented in 1844 by Francis Rynd, an Irish physician. Charles Pravaz, a French physician, invented the first practical metal syringe in 1853. See Syringe .
Hypodermic injections are named for the tissue into which the injection is made. Intradermal injections are made between the layers of skin. For these, the doctor inserts a needle just under the top layer of skin. Injections made beneath the outer layers of skin are called subcutaneous injections. Intramuscular injections are given into deep muscle tissue. A hypodermic needle can be inserted into a vein to give medicine intravenously (see Intravenous injection ).
