The key difference between C1 and C2 is that the C1 or the atlas vertebra is the most superior vertebra of the human vertebral column while the C2 or the axis vertebra is the second topmost vertebra of the human vertebral column.
The vertebral column is the bony segmented structure that provides protection to the spinal cord and that supports the thorax and head. Thus, it is a collection of many different types of vertebrae. An adult human has a total of 26 vertebrae in its vertebral column. Based on the location of the vertebrae, their names differ as cervical, thoracic, lumbar, sacral and coccyx. Accordingly, cervical vertebrae are the vertebrae located in the neck region immediately below the skull. There are 7 cervical vertebrae in the neck region. The very first cervical vertebra is the Atlas vertebra or the C1 vertebra. The second topmost vertebra is the Axis vertebra or the C2 vertebra. C1 is responsible for the ‘Yes’ motion while the C2 is responsible for the ‘No’ motion. The main purpose of this article is to discuss more details on the difference between C1 and C2.
CONTENTS
1. Overview and Key Difference
2. What is C1
3. What is C2
4. Similarities Between C1 and C2
5. Side by Side Comparison – C1 vs C2 in Tabular Form
6. Summary
What is C1?
C1 or Atlas vertebra is the most superior vertebra of the vertebral column. It is the first vertebra of the vertebral column that comprises two anterior and posterior arches and two lateral masses. Furthermore, it is the first cervical vertebra in which the head rests on. It holds the skull up.
Figure 01: C1 Vertebra
Thus, the “yes” motion of the head is possible due to this vertebra. C1 vertebra locates between the cranium and C2 vertebra. Likewise, it plays a vital role in the movement of the head and neck. Both C1 and C2 vertebrae are important for the balance of the skeleton of the human body. Furthermore, C1 vertebra supports the spinal cord and vertebral arteries as well. Not only that, it provides attachment sites for certain muscles of the neck.
What is C2?
C2 or Axis vertebra is the second topmost cervical vertebra of the vertebral column. C2 is adjacent to Atlas vertebra and C3 vertebra. It supports the head to rotate. Hence, it allows the “no” motion of the head.
Figure 02: C2 Vertebra
The most distinctive characteristic of the C2 vertebra is the vertical projection called “dens”. Moreover, this is the vertebra that joins the skull and the spine. And also C2 vertebra encases the entire brain stem. Therefore, it is an important bone for the human system’s survival and functionality.
What are the Similarities Between C1 and C2?
- C1 and C2 are cervical vertebrae located in the neck region immediately below the skull.
- Furthermore, they are highly specialized.
- Both provide a great degree of mobility for the skull. Also, they control the movement of the skull.
- Furthermore, they form a connection between the head and the spine.
- Also, C1 and C2 have unique shapes and have vertebral foramina.
- Besides, if damages occur to C1 and C2, they are most often fatal or leave the individual fully paralyzed.
What is the Difference Between C1 and C2?
C1 is the topmost vertebra that holds the skull while the C2 is the second topmost vertebra that provides an axis to rotate skull and C1 when the head moves side to side. Therefore, this is the key difference between C1 and C2. Atlas vertebra is a synonym of C1 while the axis vertebra is a synonym of C2. When considering the locations of C1 and C2, the location of C1 is between the cranium and C2 while the location of C2 is between C1 and C3. Hence, it is another difference between C1 and C2.
Furthermore, C1 supports the ‘yes’ motion of the head, while the C2 supports the ‘no’ motion of the head. C2 possesses a strong odontoid process known as the dens while C1 does not possess it. Therefore, this is a structural difference between C1 and C2. Besides, C1 is important since it holds the head upright while C2 is important since it encases the entire brain stem and it is crucial for human systems’ survival and functionality.
Below is an infographic on the difference between C1 and C2.
Summary – C1 vs C2
C1 and C2 are the very first two vertebrae of our vertebral column. They are cervical vertebrae. C1 holds the head upright while C2 encases the brain stem and it allows most of the head motions. Both C1 and C2 are unique, and they are specialized vertebrae located in the neck region. They are ring-like vertebrae. However, C2 possesses a projection called dens which is not present in the C1. Thus, this summarizes the difference between C1 and C2.
Reference:
1. “Atlas (Anatomy).” Wikipedia, Wikimedia Foundation, 5 Jan. 2019. Available here
2. “Axis (Anatomy).” Wikipedia, Wikimedia Foundation, 27 Nov. 2018. Available here
Image Courtesy:
1.”Cervical vertebra 1 animation top”By Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia
2.”Cervical vertebra 2 close-up top animation”By Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia