One of the most complest bony structures in the body is the region we call the skull.  This important part of the axial skeleton serves many functions for the body.  It serves as a "brain case" by totally surrounding the organ.  It forms the features of the face and supplies the facial region with many muscle attachments.  It contains an abundance of openings called foramina that form passageways for nerves and blood vessels.  It articulates with the vertebral column to enable us to nod our head with a "yes" type motion.  And, finally, it contains many sinus cavities that lessen the skull's weight while providing resonance for the voice.

Skull bones are divided into two groups.  These are:
        1.    cranial bones - those that come in contact with the membranes that surround the brain
        2.    facial bones - those that form the delicate features of the face while providing sites
               for muscle attachment.

Cranial bones include:

• the frontal bone - commonly called the "forehead" bone.  This bone extends into the crainal cavity and forms a shelf-like regions that supports the frontal lobe of the brain.  It also contains an open sinus cavity (do you ever get those sinus headaches when your head hurts just above the eyes?) and extends to the eye orbit, forming the roof section and lying just deep to your eyebrows.  This bone actually forms from two bones that fuse between the eyes at a point called the metoptic suture.
• the two parietal bones - form the top of the skull, joining each other at the sagittal suture.  They also touch the frontal bone anteriorly, the occipital bone posteriorly, and the temporal bone laterally.
• the occipital bone - forms the posterior, inferior part of the skull.  This thick bone protects the brain from injury while providing muscle attachment sites.  It contains the large foramen magnum, an opening for the passage of the spinal cord as it becomes brain.  On the lateral, anterior edges of this opening are a pair of occipital condyles that articulate with the first vertebra, allowing you to nod your head as to say "yes".
• the two temporal bones - form the lateral aspects of the skull and suuround the opening for the ear called the external acoustic (auditory) meatus.  This bone has many processes, one important one called the zygomatic process extends anteriorly and forms the ridge we commonly call our cheek bones.  This zygomatic process articulates with the zygomatic bone, one of the facial bones.
• the sphenoid bone - is considered to be the cornerstone of the cranial bones because is articulates with all of them!  This butterfly shaped bone forms the posterior, lateral walls of the eye orbits and extends into the cranial cavity.  Its pterygoid processes can even be seen forming the posterior walls of the mouth and throat regions.
• the ethmoid bone - is a delicate bone that forms parts of the nasal cavity and eye orbits.  It also extends into the crainal cavity with its cribriform plate and sharp ridge called the cristae galli.  This cristae galli ridge serves to anchor the meninges (the membranes that surround the brain).  The ethmoid bone is full of sinus cavities (do you ever get those sinus headaches where your eye sockets ache?)  Infections in these sinus cavities are dangerous due to the intimate association of this bone with the brain and its meninges.

The Facial Bones:

The bones of the face not only provide surfaces for the attachment of muscles but also give your face its delicate framework.  These bones include:
 

• the zygomatic bones - commonly called the cheek bones.  These bones have posterior processes called the temporal processes, that articulate with the temporal bones' zygomatic processes.  Together, they form the zygomatic arches, surfaces for the atachment of chewing (and other) muscles.
• the maxillae bones - are a pair of bones that form the upper jaw.  They also extend superiorly into the eye orbits.  Each maxilla has a flat palatine process that forms the anterior portion of the roof of the mouth.  These bones are hollow--they have lots of open sinus cavities inside.
• the nasal bones - two tiny rectangular bones at the bridge of the nose.
• the lacrimal bones - two tiny rectangular bones at the medial edges of the eye orbits.  They each have an opening along their inferior surfaces that drain tears (hence their names).
• the vomer bone - helps form the wall in the center of the nasal cavity called the nasal septum by articulating with the ethmoid bone's perpendicular plate.
• the palatine bones- a pair of L shaped bones that form the posterior mouth walls and the posterior 1/3 of the roof of the mouth.
• the inferior nasal conchae - two lateral shelf like projections in the nasal cavity, covered by mucous membranes.
• the mandible - commonly called the lower jaw.  This u-shaped bone articulates with the temporal bone.  Only the surfaces of the teeth touch the upper jaw (maxillae).

Want to learn more?  Check out the sites below!

• skull stuff - contains lots of text outlining some of the important features of the skull
• skeletal stuff - contains lots of pictures and an quiz to test your own knowledge!  This site is great!  Thank you, Rebecca for sharing it with me!