Do not sculpt individual fingers. Sculpt the carpal block (wrist), then the metacarpal fan (palm), then the proximal phalanges . The verified PDF provides "shorthand" shapes—how to simplify the 27 hand bones into just 4 primary masses.
Beginners often look for veins. Professionals look for tendons. Specifically, the Extensor digitorum tendons on the back of the hand become visible only when the fingers are slightly spread or extended. The verified PDF uses form-annihilation (showing the model in half-shadow) to highlight these tendon ridges. arm and hand in motion by anatomy for sculptors pdf verified