What two cervical vertebrae comprise the atlantoaxial joint?

• A. C1 and C2
• B. C2 and C3
• C. C3 and C4
• D. C4 and C5

Answer: (A)

The atlantoaxial joint is formed by the first two cervical vertebrae, known as C1 (the atlas) and C2 (the axis). This joint is crucial for the rotation of the head, allowing for a significant range of motion. The atlas (C1) supports the skull and allows it to nod up and down, while the axis (C2) has a peg-like projection called the odontoid process (or dens), around which the atlas rotates. This unique arrangement between the atlas and axis enables the head to turn side to side, making them essential for the overall function of the cervical spine.

Understanding the anatomy and function of these vertebrae is important for athletes and healthcare professionals, as injuries in this area can lead to serious complications. Therefore, recognizing that C1 and C2 form the atlantoaxial joint is critical in the study of human anatomy and athletic training practice.