There are some features unique to the skull. The individual bones do not always dictate the larger shapes of the skull. A suture, or meeting of two different bones, is found in the middle of a larger form. You can see this meeting particularly in the zygomatic arch as well as in the ocular orbit.

The frontal bone, the ethmoid and the maxilla have within them empty spaces called sinuses. The ethmoid bone, if cut in half, looks like a cluster of bubbles, and the walls of the sinuses are almost as thin as the wall of a bubble and are very fragile. If the skull were solid bone it would be so heavy you wouldn’t be able to hold your head up. By having empty spaces within the bones and therefore making them lighter, the sinuses are nature’s way of solving that problem. They can present other problems, however, for they are lined with mucous membranes that can become infected and get clogged up. Each sinus has a small opening into the nasal cavity which allows drainage.

Going from the top to the bottom—from head to toe—I shall illustrate all of our bones and voluntary muscles. For each part of the body I illustrate the bones involved, and with drawings and text show how and where the muscles attach to them.
In making my drawings I have referred to Gray’s Anatomy, long considered the definitive anatomy book, Frank Netter’s
Atlas of Human Anatomy, Grant’s Atlas of Anatomy, Carmine D. Clemente’s Anatomy—A Regional Atlas of the Human Body,and R.M. H. McMinn and R. T. Hutching’s Color Atlas of Human Anatomy and finally Werner Spalteholz’s Hand Atlas of Human Anatomy. I have also worked from my own drawings done from dissections. I have done the skeleton drawings from my own skulls, backbone and pelvis, other bones loaned by friends, and from whole skeletons owned by acquaintances.