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 How to Give a B12 Injection: Step By Step Instructions How I perform a glute Injection (Intramuscular Injection) YouTube B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics