Cervica - Arthrokinematics of Flexion and Extension N348

Study Notes

The atlanto-occipital joint has convex occipital condyles that roll backward in extension and forward in flexion within the concave superior articular facets of the atlas.
The atlanto-axial joint complex allows about 15 degrees of total flexion and extension and the ring-shaped atlas tilts forward during flexion and backward during extension.
Flexion and extension throughout the C2 to C7 vertebrae occur about an arc that follows the oblique plane set by the articular facets of the apophyseal joints.
During extension, the inferior articular facets of superior vertebrae slide inferiorly and posteriorly, relative to the superior articular facets of the inferior vertebrae.
The anatomic or slightly extended position of the cervical region increases the area of contact within the apophyseal joints and is often considered the apophyseal joints’ close-packed position.
The arthrokinematics of flexion throughout the intracervical region occur in a reverse fashion to that described for extension.
Flexion stretches all the components of the capsule of the apophyseal joints and reduces the area of joint contact.
About 90 to 100 degrees of cervical flexion and extension occur as a result of the sliding within the cervical apophyseal joint surfaces.
On average, about 15 degrees of sagittal plane motion occur at each intervertebral junction between C2–C3 and C7–T1.
The largest sagittal plane angular displacement tends to occur at the C4–C5 or C5–C6 levels.