topic 2 : Functional anatomy of the atlantooccipital and atlantoaxial joints.

Question 1

atlatoocipital joint

Answer 1

Type:condyloid (ellipsoid) joint.

Components: Occipital condyles of the skull articulate with the superior articular facets of the atlas (C1 vertebra).

Ligaments:
-Anterior Atlantooccipital Membrane: Connects the anterior margin of the foramen magnum to the anterior arch of the atlas.
-Posterior Atlantooccipital Membrane: Connects the posterior margin of the foramen magnum to the posterior arch of the atlas.

Movements:
-Flexion and Extension: Allow nodding movements of the head (e.g., nodding “yes”).
-Lateral Flexion: Limited due to the shape of the articulating surfaces.
-Rotation: Minimal due to the convex shape of the occipital condyles.

Question 2

atlantoaxial joint

Answer 2

Type:
Articulation: Synovial, pivot (trochoid) joint.

Components: Atlas (C1) articulates with the axis (C2) vertebra.

Articulating Surfaces:
-Dens (Odontoid Process): Peg-like process projecting superiorly from the body of the axis.
-Anterior Arch of Atlas: Contains a facet for articulation with the dens.

Ligaments:
-Transverse Ligament of the Atlas: Holds the dens in place against the anterior arch of the atlas.
-Alar Ligaments: Attach from the sides of the dens to the lateral margins of the foramen magnum.

Movements:
-Rotation: Mainly occurs between the atlas and the axis, allowing the head to turn from side to side (e.g., shaking “no”).
-Limited Flexion and Extension: Due to the shape and orientation of the articulating surfaces.
-Limited Lateral Flexion: Restricted by the alar ligaments and the shape of the joint.