The key difference between atlas and axis vertebrae is that the atlas vertebra is the topmost vertebra which holds the skull while axis vertebra is the second topmost vertebra which provides an axis to rotate the skull and atlas vertebra when the head moves side to side.
Cervical vertebrae are the vertebrae in the neck region, immediately below the skull. There are seven cervical vertebrae in the vertebral column (C1 – C7). They lay between the base of the skull and thoracic vertebrae. Atlas vertebra is the first cervical vertebra (C1) while axis vertebra is the second cervical vertebra (C2).
CONTENTS
1. Overview and Key Difference
2. What is Atlas Vertebra
3. What is Axis Vertebra
4. Similarities Between Atlas and Axis Vertebrae
5. Side by Side Comparison – Atlas vs Axis Vertebrae in Tabular Form
6. Summary
What is Atlas Vertebra?
Atlas vertebra (C1 vertebra) is the most superior vertebra of the vertebral column. It is the first vertebra in which the head rests on. It holds the skull up. The “yes” motion of the head is possible due to this vertebra.
Figure 01: Atlas Vertebra
This vertebra is between the cranium and axis vertebra. It comprises two anterior and posterior arches and two lateral masses. Both atlas and axis vertebrae are important for the balance of the skeleton of the human body.
What is Axis Vertebra?
Axis vertebra (C2 vertebra) is the second topmost cervical vertebra. It is adjacent to Atlas vertebra and C3 vertebra. Head rotates due to the axis vertebra. It allows the “no” motion of the head. It has a vertical projection called “dens”.
Figure 02: Axis Vertebra
Axial vertebra joins the skull and the spine. It also encases the entire brain stem. Therefore, it is an important bone for the human systems’ survival and functionality.
What are the Similarities Between Atlas and Axis Vertebrae?
- Atlas and axis vertebrae are two vertebrae in the vertebral column.
- Both are cervical vertebrae.
- They both are in the neck region.
- These two vertebrae are responsible for the motions of the head.
- Both vertebrae are ring-like bones.
- Both are important for the balance of the skeletal frame of the human body.
What is the Difference Between Atlas and Axis Vertebrae?
Atlas vs Axis Vertebrae |
|
| Atlas Vertebra is the first cervical vertebrae of the vertebral column | Axis Vertebra is the second cervical vertebra of the vertebral column. |
| Synonyms | |
| Also known as C1 vertebra | Also known as C2 vertebra |
| Head Motion | |
| Allows the “yes” motion of the head | Allows the “no” motion of the head |
| Projection | |
| Does not have a projection | Has a vertical projection called “Dens” |
| Recyclability | |
| Does not provide an axis to rotate the skull | Provides an axis for skull rotation |
| Superiority | |
| Most superior vertebra | Second most superior vertebra |
| Functions | |
| Holds the head upright and allows the “yes” motion of the head | Joins the spine and the skull and allows most head motions including “no” motion |
| Importance | |
| Important to hold the head upright | Important since it encases the entire brain stem. It is crucial for human systems’ survival and functionality |
Summary – Atlas vs Axis Vertebrae
Atlas and axis vertebrae are two cervical vertebrae of the vertebral column. The key difference between atlas and axis vertebrae is that the atlas vertebra is the most superior vertebra. It holds the head upright. Axis vertebra is the second most superior vertebra of the vertebral column. It encases the brain stem, and it allows most of the head motions.
Reference:
1.“Cervical Vertebrae – Anatomy Pictures and Information.” InnerBody, Available here.
Image Courtesy:
1. “C1 lateral” By By Anatomography – en:Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia
2. “C2 lateral” By Anatomography – en:Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia