I'm studying the head this month. Here are the bone landmarks I'm working to memorize:
Frontal bone - the forehead, the largest frontal plane on the face
Superciliary Arch - underneath the eyebrow, sticks out more than the forehead
Nasal bone - very short, actual nose extends further
Orbital cavity - where the eyeball sits, much larger than you might expect
Zygomatic bone (Arch) - curved bone below eye, sits between down plane underneath eye and the cheek form made by jawbone
Maxilla - upper row of teeth, larger space than you might expect
Mandible - jawbone, shape of it has major effect on shape of face/head.
The image above is my "test". The left column is me drawing from memory (original images posted earlier in the week). The right column is a quick "correction" where I reviewed what I had forgotten on the left. I've discovered that if I write something down, particularly in pictorial form, I remember it. This year I am trying to learn to draw figures from memory, the goal is to be more able to draw what I can see in my mind.