You're correct: the question mark is the teres major, which is underneath the long head of the triceps from this view.

the pose is stiff because that arm is not relaxed. If you look at your arm in the mirror unless you are flexing, your arms never stay perfectly straight. To me the shading is on point. the arm looks like it is at the top end of a push up.

Hi @younchen, nice study! I think the anatomy looks pretty accurate! The triceps seems to originate and insert correctly, and I think you're correct about that bump being the brachialis. - I would recommend starting with a gestural lay-in similar to how Stan does it. There is a nice overal s-curve in the reference of this arm that I think you missed out on. - You're showing the medial head appearing on the inside of the arm, but I can't see it in the reference. - Try to design the tendon more asymetrically, as described in the How to Draw Triceps – Anatomy for Artists video. I like to think of a circus tent when I draw it. - The main anatomical error I see is the insertion of the deltoid. In your drawing it's not inserting into the humerus, as it should. - I might've placed the humerus differently, a little more central in the arm. Hope this helps :) Keep up the good work!

Hi @Sita Rabeling, really nice study! The anatomy seems accurate to me and it's well drawn. - You might want to indicate the tail of the lateral head more clearly. Remember the "comma" shape from the lesson video? (How to Draw Triceps – Anatomy for Artists at 02:34) - The placement of the acromion process might be a little off. It's hard to get right :) The 3D Model: The Deltoids, taught me something that has helped: Note how the top row of fiber bundles are like 3 feathers, with the point facing downwards. I interpret it as if each "feather" attaches to 1 of the acromion's 3 planes. So if you see the posterior feather you know where the back of the acromion is. In this photo of Laura you can see it clearly (marked x in the paintover) (I'm not 100% this is true for all deltoids. @Stan Prokopenko, @Andrew Joseph Keith, do you know if it is? When I check Goldfinger's book it seems to be the case, but in Peck's book it's not shown clearly.) - One thing that can help with making the drawing read even more clearly and look even more finished is to have a clear hierarchy of line thickness; thickest for the outline of the arm, thinner for the outline of muscles, thinnest for details within those muscles - In the photo, the arm has a subtle s-curve. Keep that in mind for your next study; start with a light gesture drawing before adding details. Hope this helps :) Keep up the good work!

I think your ridge muscle should connect higher and more to the front, compared to the tricep. Hope that helps.

Great!

Looks accurate! It's not strange that you couldn't find the medial head. I can't see it bulging, changing the contour like the long head, either. It's covered by the tendon.

haha I think it is just a bit thicker which makes look that way.