Have you ever wondered why doctors love giving injections in that one part of the body ( buttocks ) more than others, i mean its not like the buttocks is a different body on its own, so why? Here are 6 reasons why:
1. It's the thickest part of everyone's body. Good place to hit fat.
2. Some vaccines are fat soluble, so you get them in the butt, and some need to go into muscle tissue, so you get them in the arm.
3. The area they inject is relatively free of any major nerves or big blood vessels. Just safer.
4. Because some shots absorb better in fatty tissue (butt/abdomen) than muscle (deltoid). it's not the doctor's choice, it's science.
5. Because it is the less painful spot
6. There are a few muscles where you can give injections. However, there are limits on each site.
You can't inject much volume into someone's arm, but the large muscle bulk of the gluteus (ass muscle) group means you can put in large amounts without much of an issue. You can put a decent amount into someone's thigh. But it's often more hassle (you have to get them to pull down trousers even further down) and there are more structures (nerves, vessels) close to the muscle that you need to avoid.