IM injections

Yes, it happens a lot.

Yes, that indicates nerve involvement. You've struck some kind of nociception pathway. Nothing wrong with that, but contraction is normal to any part of the body experiencing pain, whether the subject is aware of it or not.

So, I guess my concern is whether or not my technique was off. I mean, you don't want to hit a nerve when adm a injection. Thought I was right on, but obviously not. I do not normally give IM injections. I decided to give it in the arm, and did my best to use good technique. Are there any good websites or videos for demonstration? Thanks.

The major nerve pathways of the arm are inferiorly anterior and do not lie near the deltoid. There are receptors in the muscle tissue that are considered minor pathways. If one of those is struck, it can cause the twitching.

chet_wilson_drugguides_1|Medication Administration Techniques|Injections

Reference the deltoid chart. You want to aim for the middle of that triangle. Just have confidence and stick 'em quick. I pull the cap, count to three and boom. The slower you go or if you are shaky, the worse it will be for them. It's not gonna feel good, and there is no way to make it feel good. Once you accept that, just go for it.

That involuntary contraction of the muscle is always a bit surprising, but it is not uncommon, as other have stated. I wonder though...you mentioned that you "decided to" give it in the deltoid. What med/vaccination was it you decided to give in the deltoid?