What is the Difference Between Atlas and Axis Vertebrae?

The atlas and axis vertebrae are the first two cervical vertebrae in the neck region, located just below the skull. They play crucial roles in supporting the head, allowing head movements, and protecting the spinal cord. Here are the key differences between the atlas and axis vertebrae:

• Position: The atlas (C1) is the first cervical vertebra and is present just under the head, while the axis (C2) is the second cervical vertebra.
• Function: The atlas vertebra supports the skull and holds it upright, not allowing much movement. The axis vertebra forms a pivot upon the atlas and allows the head to turn side to side.
• Articular Disks: The atlas vertebra lacks superior and inferior articular disks, while the axis vertebra contains both.
• Spinous Process: The atlas vertebra does not have a spinous process, whereas the axis vertebra has a spinous process.
• Dens: The axis vertebra has a vertical projection called "dens".

Both the atlas and axis vertebrae are important for the balance of the human body and have a neurological significance, as the brainstem extends down to the axis. The joint between the atlas and axis vertebrae is called the atloaxoid joint, which allows the head to turn from side to side.

Comparative Table: Atlas vs Axis Vertebrae

Here is a table comparing the differences between the atlas and axis vertebrae:

Both the atlas and axis vertebrae are important for the balance of the human skeleton and play crucial roles in head and neck movement. The atlas vertebra is the topmost vertebra and holds the skull, allowing the "yes" motion of the head. The axis vertebra, on the other hand, is the second topmost cervical vertebra and enables head rotation, allowing the "no" motion. Together, they facilitate a wide range of motion for humans compared to animals.