Common IM Injection Sites Deltoid (Upper Arm) Location: About 23 finger widths below the acromion process (shoulder bone). Best for: Vaccines and small volume injections (1 mL). Notes: Easy to access but limited Administration of vaccines The Australian Immunisation Handbook Subcutaneous Injection: What It Is and How to Give One B12 vitamin Store How to Perform a Subcutaneous Injection of Vitamin B12