Intramuscular (also IM or im) injection is the injection of a substance directly into a muscle. In medicine, it is one of several alternative methods for the administration of medications (see route of administration). It is used for particular forms of medication that are administered in small volumes. Depending on the chemical properties of the drug, the medication may either be absorbed fairly quickly or more gradually. Intramuscular injections are often given in the deltoid muscle of the arm, the vastus lateralis muscle of the leg, and the ventrogluteal and dorsogluteal muscles of the buttocks. Depending on the injection site, an administration is limited to between 2 and 5 milliliters of fluid.