When you get a shot in the arm, how can you be sure the contents are being released into a blood vessel?

Question

When you donate blood the needle goes into a large, visible vein in your arm or hand but when getting a shot the needle just goes somewhere in your arm.

In: Biology

Answer 1

Many injections don’t have to be directly into a blood vein/artery. Just injecting into muscular tissue alone provides fairly rapid absorption into the bloodstream without the risks of using a vien.