Skull anatomical Illustration

Prismacolor on 11x14 bristol

I am really proud of this. I estimate this took about 20 hours.
This was done for an assignment in my advanced anatomy class. We were assigned to do 5 full anatomical renderings, one of them being the skull. The assignments were very open-ended, and we were given free reign on what we preferred to show. For the skull, I thought this would be a great opportunity to explore both the musculature and the bones.
I took a photo of my friend Jordan as reference, and with the assistance of my teacher, I was able to locate most of the anatomical structures from surface landmarks. I decided to use an image that was more of a 3/4 angle instead of a straight profile and of my friend screaming, because it would be a great opportunity to learn how the muscles work at a different angle, and a different facial expression. And after using multiple anatomy books as reference for this piece, I will definitely attest to the fact that I have not seen one skull illustration from this angle or expression!

I've been using prismacolors since my sophomore year of high school, and I feel that 7 years later I'm really starting to develop a technique. The only thing I'd consider changing is his shirt. But please, feel free to critique! I'm very open to hearing others' opinions of my work, and how I can improve.