Skeleton | Skeletal System Overview
Axial Skeleton
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Introduction
Anatomists divide the skeletal system into axial skeleton and appendicular skeleton.
The axial skeleton is the central part of our body and includes 
the skull, the hyoid bone, the vertebral column, the sternum, and the ribs. The appendicular skeleton includes the bones of the limbs (e.g., the upper and lower limbs) and the girdles (e.g., the shoulder girdle and the pelvic girdle).
In this tutorial, we will dive into the anatomy of the axial skeletal system.
Skull
The human skull is a protective vault, for our most critical organ, the brain. It consists of 22 bones divided between the neurocranium (braincase) and viscerocranium (facial skeleton).
Make sure to check our tutorials covering both the cranial bones and the facial bones.
Hyoid bone
The hyoid bone is a small u-shaped bone that does not articulate with any other bone, connecting to its neighboring structures by muscles and ligaments.
It is 
located at the midline at the level of C3, providing stability to the adjacent structures and playing a critical role in the movement of the upper airway.
Vertebral column
Also called the spine or backbone, the vertebral column is a continuous series of vertebrae separated by intervertebral discs. There are usually 33 vertebrae named according to their region as follows:
- Cervical vertebrae (7)
- Thoracic vertebrae (12)
- Lumbar vertebrae (5)
- Sacrum (5 fused) & coccyx (4 fused).
The vertebral column houses and thus protects the spinal cord, supports the upper body’s weight, and plays a vital role in a wide range of movements.
Rib cage (thoracic cage)
The rib cage consists of the thoracic vertebrae, twelve pairs of ribs (and their corresponding costal cartilages), and the sternum.
It is an essential component of the respiratory system, protecting the lungs and the heart, and helping with breathing.
Sternum
Also called the breastbone, the sternum is located at the midline anteriorly articulating with the clavicles and costal cartilages of the ribs.
Ribs
The ribs are further divided into true ribs (1-7), false ribs (8-10), and floating ribs (11-12).
