Which muscle is most appropriate for administering a 2.5 mL intramuscular injection in an adult?

The dorsogluteal muscle has been traditionally used for administering intramuscular injections, particularly for larger volumes, such as 2.5 mL. This muscle is located in the upper outer quadrant of the buttock and is a large, well-developed muscle that can accommodate larger volumes of medication. Historically, it was favored for intramuscular injections due to its size and depth, allowing for a safe administration with minimal risk of hitting important structures.

While the deltoid, ventrogluteal, and thigh muscles can also be used for intramuscular injections, they each have limitations with regard to volume. The deltoid, for example, is generally used for smaller volumes (up to 1 mL) due to its size and the proximity of the axillary nerve and radial nerve, making it less suitable for a 2.5 mL injection. The ventrogluteal site is actually recommended as a safe injection site as it contains a large amount of muscle and is away from major nerves and blood vessels; however, the dorsogluteal site is still historically noted for larger volumes despite concerns over potential complications. The thigh (vastus lateralis) can also accommodate larger volumes; however, the dorsoglute