The humerus is generally longer than the forearm.
The hand is a collection of small arches. If you sculpt the hand flat, it will look like a mannequin. The Three Arches of the Hand: The curve across the knuckles. anatomy for sculptors arm and hand in motion pdf free
Are you using (ZBrush/Blender) or physical clay ? The humerus is generally longer than the forearm
Offers older public domain classics like A Manual of Artistic Anatomy or Classic Human Anatomy in Motion (borrowable). anatomy for sculptors arm and hand in motion pdf free