Library · Anatomy
The skeleton of the head and trunk
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The axial skeleton is the part of the skeleton that forms the body's axis, the vertical line that runs down its center. It has 80 bones: the bones of the head, the bones of the spine, the ribs and the sternum, the flat bone in the middle of the chest. Picture a vertical mast with a cage of bones built around it.
The spine has 33 vertebrae, the stacked bones you can feel if you run a finger down the middle of your back: 7 in the neck, 12 in the rib area, 5 in the lower back, 5 in the sacrum and 4 in the tailbone. The skull, in turn, usually has 22 bones held together by seams called sutures.
And it is not just structure: it is armor. The bones of the skull, which are fused, surround the brain; the vertebrae surround the spinal cord, the thick cable of nerves that runs down the back; and the ribs help protect the heart and the lungs.
In brief
The axial skeleton comprises the 80 bones that form the body's vertical axis: the bones of the head, the spine, the ribs and the sternum.
A vertical mast with a cage of bones built around it.
That axis includes 33 vertebrae, 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal, plus the skull, which usually has 22 bones joined by sutures.
The fused skull surrounds the brain, the vertebrae surround the spinal cord, and the ribs help protect the heart and lungs.
Sources (4)
- SEER Training Modules, National Cancer InstituteDivisions of the Skeleton, SEER Training Modules
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Back, Vertebral Column, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Head and Neck, Skull, StatPearlsPublished
- SEER Training Modules, National Cancer InstituteIntroduction to the Skeletal System, SEER Training Modules
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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