Atlantoaxial joint

A pivotal joint located between the first and second cervical vertebrae that enables a range of head movements.

The atlantoaxial joint is a complex joint situated between the atlas, the first cervical vertebra, and the axis, the second cervical vertebra. This joint plays a crucial role in the ability to rotate the head and perform lateral nodding. It is classified as a pivot joint, allowing for rotation around a single axis.

Terminologia Anatomica

articulatio atlantoaxialis

System

Skeletal system

Function

The primary function of the atlantoaxial joint is to facilitate the rotation of the head. This joint allows the skull to pivot around the dens, or odontoid process, which is a bony projection from the axis. As a result, when the head turns from side to side, such as in the motion of shaking the head 'no,' the atlantoaxial joint is heavily engaged. In addition to rotation, this joint contributes to nodding movements; while a more pronounced up-and-down motion occurs at the atlanto-occipital joint, the atlantoaxial joint plays a supportive role in these actions. Furthermore, maintaining stability at the atlantoaxial joint is essential for preventing excessive movement that could lead to injuries or neurological impairments, such as those associated with whiplash or trauma to the cervical spine.

Location

The atlantoaxial joint is situated at the uppermost part of the spine, between the first cervical vertebra (C1), known as the atlas, and the second cervical vertebra (C2), known as the axis. This joint is located just beneath the skull's base, at the suboccipital region. It allows for the unique anatomical arrangement that enables extensive mobility of the head while supporting the crucial structures of the brainstem and upper spinal cord. The atlantoaxial joint's position also places it at a critical intersection of the central nervous system and the musculoskeletal system, highlighting its importance in both movement and neurological function.

Did You Know?

The dens of the axis fits into a bony socket in the atlas, which is what allows for the rotation of the head.
The atlantoaxial joint is one of the most mobile joints in the human body, accounting for approximately 50% of the total head rotation.
It is commonly affected by conditions such as arthritis, which can lead to restricted movement and discomfort.