Any common muscle close to ventro injection site?

[Fiskevatten]

Probably a wierd questions.
But i can't seem to inject correct in my left ventro. Right ventro is no issue, muscle there is much more visible. But the left is a pain in the ass.

Today i had to flex to find it and inject. First injection hit something, no pain just plain felt wrong probs a small vein or something. Pulled out and tried again.
During injection second time the muscle started to "retract" itself making the needle inject half inch. When i tried to push it in further my leg started jumping lol
(might be from the flex but that is usually no problem. Nerve should have felt much more).
So basically i've injected wrong, somehow missed ventro i'd guess.
Some oil sipped out but not too much. Massaged the area and cleaned it.

Is there any small muscles around ventro that I might have hit instead, close to ligaments or such? All other injection sites are fine, just left ventro.

[milkshakes]

Hey, I've been trying to find some information about finding the ventro site on myself... Any tips? I don't have someone to inject for me.