Understanding the hand
There are many different ways to see and understand how to draw the human hand. I started by creating the hand with clay and then diving into anatomy. Anatomy may seem overwhelming but once you remember the definition it is easier to remember the terms. For example, pollicis is from Latin. It is possessive from pollex, which means thumb.
There are four muscles that moves your thumb at the palm of your hand. Adductor pollicis, flexor pollicis brevis, abductor pollicis brevis and opponens pollicis. See the word pollicis? What does that mean for you as an artist? Remember there's a bulge in your hand created by the muscles for the thumb (pollicis). Think of the bulge (red area in drawing above) when you shade or paint.
The phalanges are the bones that make up the fingers of the hand and the toes of the foot. It means "line of battle in close ranks," from Latin phalanx. Do you see your fingers as soldiers getting things done? The green area, thenar, in picture above shows the knuckles. This is where phalanges and metacarpals attached. When you draw remember this bumpy region and for shading.
The blue area, hypothenar, in the picture above show the region where it is responsible for moving your small finger. Here's another small mass of muscles that you need to keep in mind for drawing and shading.
What does this all mean? You have at least three bulges to keep in mind when drawing. When light falls on everything, there needs to be a valley in the middle of the hand to give that extra depth.
Let me know what else you would like to know about your hand.