[sheezy1]

[J_9]

Copaxone is not to be used intramuscularly. It is supposed to be used subcutaneously. The best way to explain this is to pinch the skin/fat of your belly. This would be subcutaneously.

Areas for self-injection include arms, abdomen, hips, and thighs. And all sites should be rotated with each dose.

[sheezy1]

I should have said Avonex

[J_9]

This is also a subcutaneous medication, not an intramuscular.

You should inject this medication on the same 3 days every week, for example, every Monday, Wednesday, and Friday. The injections should be spaced at least 48 hours apart, so it is best to inject your medication around the same time of day on each of your injection days. The best time to inject this medication is in the late afternoon or evening.

Found here... PubMed Health - Interferon beta-1a Subcutaneous Injection

Also, I have bolded the primary answer to your question...

You can inject interferon beta-1a in areas of your body with a layer of fat between the skin and muscle, such as your thigh, the outer surface of your upper arms, your stomach, or your buttocks. If you are very thin, only inject in your thigh or the outer surface of your arm for injection. Use a different spot for each injection.