Different Injection Sites Every Nursing Student Should Know Understanding injection sites is essential for safe and effective drug administration. 1 Deltoid (Upper Arm) Located in the upper arm muscle Used for: Giving an intramuscular injection Resource Library Sheffield Children's NHS Foundation Trust How to Give a B12 Injection: Step By Step Instructions How to Give a B12 Injection: Step By Step Instructions Using the ventrogluteal site for intramuscular injection Best Vitamin B12 Injection Sites: Where to Inject B12 PA Relief