"atlanto-occipital joint: hyaline-covered synovial joint between the occipital condyle and concave facet of the lateral mass of the atlas. Covered by a capsule and innervated by C1, this joint allows for flexion, extension and lateral flexion."
"median atlantoaxial joint: hyaline-covered synovial joint between the dens of the axis and the posterior aspect of the anterior arch of the atlas, allowing for the rotation of the head. The dens is held in place by the transverse ligament, with a bursa between the two."
"lateral atlantoaxial joint: hyaline-covered synovial joint between the inferior articular facet of the atlas and the superior articular facet of the axis which allows for the rotation of the head. A capsule innervated by the C2 nerve surrounds the joint."
"transverse ligament: strong band that runs posterior to the dens of the axis, holding it in place. Each end is attached to tubercles on the anterior arch of the atlas."
"atlantoaxial ligaments: attach from the lower border of the anterior arch of the atlas to front of the body of the axis. Provides tertiary support against ventral translation of the dens."
"posterior atlanto-occipital membrane: attached to upper border of the posterior arch to the outer margins of foramen magnum. At each lateral margin, there is a gap for the passage of the C1 nerve and vertebral artery, which sometimes ossifies and becomes a foramen. Innervated by C1."
"The atlas is composed of an anterior arch and a posterior arch, paired lateral masses, and paired transverse processes. It does not have a vertebral body, instead the dens of the axis sit where a centrum (body) of a typical vertebra would be. The transverse ligament holds the dens of the axis against the anterior arch of the atlas and divides its vertebral canal into two parts. The anterior 1/3 is occupied by the dens. The posterior 2/3 contains the spinal cord, which occupies 1/3 of the total vertebral canal space."
"Transoral AP view best appreciates the atlantoaxial joint"
"sum of displacement of lateral masses of C1 compared to C2 >8 mm on transoral AP view 6"
Expected headings
"Articulations"
"Ligamentous"
"Musculotendinous"
"The atlas (plural: atlases) is the first cervical vertebra, commonly called C1. It is an atypical cervical vertebra with unique features. It articulates with the dens of the axis and the occiput, respectively allowing rotation of the head, and flexion, extension and lateral flexion of the head. Unlike the rest of the cervical vertebrae, with exception to the similarly structured axis, the anterior rami are sent posteriorly instead of anteriorly."
"superior articular facet: kidney-shaped, concave and articulates with the occipital bone"
"atlanto-occipital joint: hyaline-covered synovial joint between the occipital condyle and concave facet of the lateral mass of the atlas. Covered by a capsule and innervated by C1, this joint allows for flexion, extension and lateral flexion."
"Ossification starts from three centres: anterior ossification centre, and paired lateral mass ossification centres. The paired lateral mass ossification centres arise in week 7 and extend to the posterior arch. Unification at the posterior arch occurs at years 3-4 and is typically direct, but can sometimes involve a third centre at the posterior arch. The anterior ossification centre unites with the lateral mass ossification centre at years 6-8. There are sometimes two anterior ossification centres."