Head

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.