The human skull isn't just one
Jolly Roger-looking bone with a jaw bone hanging off of it. The human cranium is actually an interlocking set of 23 bones (well, 22, because the Adam's Apple doesn't touch the others ...)
Here's what's going on inside your head:
Bones of the human cranium:
Paired Cranial Bones:
Unpaired Cranial Bones:
- Frontal
- roughly, the forehead and upper part of the eye orbit.
- Occipital
- the flat, concave base, which rests upon the first vertebrae. The occipital bone has a hole, the Foramen Magnum
, through which the blood vessels and nerves of the spine connect with the base of the brain.
- Sphenoid
- difficult to describe; winged, with many fissures and protusions. It roughly leads from the sinuses to the eyes.
- Ethmoid
- also hard to describe; cannot be seen from every angle of the skull. Like the sphenoid, it is located in the the mid-sagittal plane and helps connect the cranial skeleton to the facial skeleton. It consists of various plates and paired projections. The most superior projection is the Crista Galli
, (or "cocks comb," owing to its appearance), which helps divides the left and right frontal lobes of the brain.
Paired Facial Bones:
- Lacrimals
- these two are the smallest and most fragile of the facial bones, forming the front of the side wall of each eye orbit. Basically rectangular with two surfaces and four borders. Each of the four borders articulate with the bones that surround them.
- Nasals
- two small rectangular bones which form the bridge of the nose above the nasal cavity
- Zygomatics
- the cheekbones, running from the maxilla to the wall of the eye orbit.
- Maxillae
- the paired upper jaw bones. They are nearly hollow, each with a large cavity called a maxillary sinus.
- Palatines
- wing-shaped. They assist in forming the rear of the hard palate and part of the nasal cavity.
- Inferior Nasal Conchae
- small and complicated. These conchae are thin, porous, and fragile. They are elongated and curled in on themselves. They lay horizontally and are attached to the side wall of the nasal cavity. They increase the surface area inside the cavity and increases the amount of mucus membrane and olfactory nerve endings exposed to the air.
Unpaired Facial Bones:
- Vomer
- forms the nasal septum, creating the left and right nasal passages. The part of the nose that most often gets broken.
- Mandible
- the lower jaw. The formal anatomical name for its tip (the chin) is the mental protuberence.
- Hyoid
- the small U-shaped bone in the front of the throat, under the jaw but above the larynx. (the "Adam's Apple.")
Resources:
http://www.lib.uiowa.edu/commons/skullvr/ - pictures of the skull's bones.
http://www.csuchico.edu/anth/Module/skull.html - more pictures of the skull's bones.
http://education.yahoo.com/reference/gray/ - search
Gray's Anatomy, the
gold standard of all
anatomy reference texts.