Atlanto-axial joint

Atlanto-axial joint is a joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis. It is a pivot type of joint, allowing for rotation of the head.

Etymology

The term "atlanto-axial" is derived from the names of the two cervical vertebrae involved in the joint: the atlas (C1) and the axis (C2). The atlas is named after the Greek Titan Atlas, who was condemned to hold up the sky for eternity, as the atlas vertebra holds up the skull. The axis is so-named because the skull and atlas rotate about it.

Anatomy

The atlanto-axial joint is a complex of three joints: two lateral atlantoaxial joints and one median atlantoaxial joint. The lateral joints are plane synovial joints between the facets of the atlas and axis. The median joint is a pivot type of joint between the dens of the axis and the anterior arch of the atlas.

Function

The primary function of the atlanto-axial joint is to allow for rotation of the head. This is accomplished through the pivot-like median atlantoaxial joint. The joint allows for approximately 50% of the rotation of the neck.

Clinical significance

Injuries or abnormalities of the atlanto-axial joint can lead to significant problems due to the joint's proximity to the brainstem and its role in head and neck movement. Conditions such as atlantoaxial instability and atlantoaxial subluxation can occur due to trauma, congenital abnormalities, or degenerative diseases.

See also

• Cervical vertebrae
• Atlas (anatomy)
• Axis (anatomy)

References

• Atlanto-axial joint - Gray's Anatomy illustration
  Atlanto-axial joint - Gray's Anatomy illustration
• Atlanto-axial joint - Gray's Anatomy illustration
  Atlanto-axial joint - Gray's Anatomy illustration
• Normal atlanto-dental joint on X-ray
  Normal atlanto-dental joint on X-ray