Skull Bones: Occipital

The skull is complicated if you don’t approach it one thing at a time.  A great way to start is to examine the flat bones of the skull. Then, look at the suturesImmovable joints between skull bones; zigzag or wavy seams. that connect them to each other.  Before getting started, note that there are two structures within the skull. The cranial vault is where your brain is. Then, there are your facial bones, where your brain isn’t.  

The occipital bone forms part of the posterior wall of the cranium and the inferiorBelow or toward the lower part of the body. surface of the skull.  It articulates with each of the parietal bones at the lambdoid sutureInverted “V” shape between occipital and parietal bones on the back of skull..  It also articulates with the temporal boneBones on the sides of the skull near the ears; house structures of hearing and balance. at the occipito-mastoid suture.  

The hole in the middle of the occipital bone is where the spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae. punches through and connects to the brain.  This is called the spine hole.  No, it’s called the magnum foramen, meaning large hole.  I just once had a class that kept calling it the spine hole.  

The two occipital condylesSmooth, oval projections beside the foramen magnum; articulate with the atlas vertebra. are lateralAway from the midline of the body. to the magnum foramen.  You are thinking that these can’t be condyles.  We know condyles as knubby ends of bones like the femurThigh bone; longest and strongest bone in the body; has a large round head and prominent trochanters.  Well, this applies here, kinda.  These are little nubs, sticking out from the flatness of the bone.  These nubs sit on the atlasFirst cervical vertebra; ring-shaped, no body; supports the skull at the occipital condyles (“yes, which is C1, or the most superiorAbove or toward the upper part of the body. vertebra.  Atlas was a Titan who held the weight of the world on his shoulders.  The atlas has structures that cradle these condyles allowing you to nod your head yes.  Go ahead and nod your head.  As you do, these occipital condyles rock on the atlas. They move back and forth like a rocking chair does on the floor.  We’ll talk about shaking your head no when we go over vertebrae.