Vitamin B12 and ulcerative colitis: Links and more 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 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 Areas to Inject Tirzepatide: FDA Approved Sites and Proper Technique Fella Health Vitamin B12 Injections In London & Birmingham Dr Fasano