Try putting down where the scapula and humerus are. You know the ulna connects with the humerus and you know the radius connects with the wrist. Also, the forearms are pronated so you know the radius has rotated to cross the ulna. You can see the Afro ion and the epicondyles so crack open an anatomy book with a similar pose or you could use the Skelly app and reproduce the pose to understand it. That’s how I would attack the problem, anyways

Sundjiv. I would say that the lines that you see in your top two circles are both indicating the division between the infraspinatus mm and the teres major muscle. Your bottom left circle is primarily in the area of the latissimus dorsi (lats) as it wraps from the back moving up towards its insertion on the upper/inner arm. Hopefully that helps.

Hi Sundjiv, I'm really late (and you might have figured it out by now), but here goes: Top ellipse: The muscle here is infraspinatus. Beside it is a depression that corresponds to the teres minor, and below teres minor, we can see teres major bulging out. Bottom left ellipse: It's the serratus anterior. Above, on the medial edge of the scapula, there is a triangular depression that corresponds to the rhomboid. Right ellipse: This is again the infraspinatus. I hope I cleared up some of the confusion. The back can be very frustrating with all these muscles stretching and contracting. Best of luck with your anatomy studies.

This is great

Hi @Sundjiv, Nice studies! I think you're really close with the ribcage! I attached a tracing of how I think I would've have done it I hope this helps :)