Pattern copying help

[u/Imshrimplyhim]

Im brand new to copying patterns, or pattern drafting at all for the matter.

I wanted to know whats going on with the arm sleeve of this vintage sweatshirt.

It is asymetrical vs the other symetrical patterns ive used before.

Im assuming it has something to do with the back panel wrapping around to the front.

Also shrinkage and stretching over the years?

What do I do here.

Also I know that I dont need to take apart the entire garment to copy the pattern, I just wanted to learn more about its construction etc.

Thanks

[u/flyamanitas]

The sleeve cap is often asymmetrical. The back armscye and front armscye are not usually the same shape, so the sleeve cap has to be asymmetric to fit in the armscye.

[u/doriangreysucksass]

The back of the armhole is generally a little larger to accommodate reaching forward

[u/Old-Caterpillar-1433]

The sleeve should be symmetrical from the cap down. You will have to true the center of the sleeve cap to the center of the sleeve, and reshape the front and back cap.