• C1 = atlas (holds the skull)

• C2 = axis

  • odontoid process = dens = peg

• a pivot joint

• pivot articulation between

  • odontoid process of C2
  • ring formed by
    • anterior arch C1
    • transverse ligament C1

There are 4 joints (a triple joint)

• median atlanto-axial joint
  • one
    • posterior surface of anterior arch C1
    • anterior surface of odontoid process C2
    • this is the joint distance that is measured
  • two
    • posterior surface of odontoid process C2
    • anterior surface of transverse ligament C1
• lateral atlanto-axial joints (2)
  • lateral mass C1
  • lateral mass C2