Anatomy and biomechanics of the craniovertebral junction

Abstract

<jats:p>The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques.</jats:p>

Morphometric multislice computed tomography examination of the craniovertebral junction in neck flexion and extension

“…Whilst the C1-C2 joints are essential in head rotation, the right and left Oc-C1 joints are crucial in flexion and extension. The mentioned syndesmoses stabilise the CVJ complex, but also restrict hyperflexion, hyperextension and hyper-rotation, thus protecting the joints themselves, but also the nearby valuable vascular elements and vital neural structures [19,22,34]. The excessive movements within the Oc-C1 joints are limited by the alar ligaments, the transverse ligament of the atlas and, perhaps, by the tectorial membrane [22,34].…”

“…Thus, most of the cranial flexion, extension and rotation are performed at the CVJ [19]. For this reason, many authors examined the movements of the CVJ, which are enabled by the CVJ bones, that is, the occiput, atlas and axis, connected by certain joints: the atlanto-occipital (Oc-C1), and the median and lateral atlantoaxial joints (C1-C2) [19,22,34].…”

“…According to certain authors [19,22,29,34], the range of flexion in the Oc-C1 joint averages 23.0-27.1 o , lateral bending is from 3.4 o to 5.5 o , and axial rotation varies between 2.4 o and 7.2 o . As regards the C1-C2 joints, the mean value of flexion is 10.1 o .…”

“…The craniovertebral junction (CVJ), in the narrower sense, consists of the right and left occipital condyle (Oc), the atlas (C1) and the axis (C2) [19,22,34]. Flexion and extension of the cervical spine, including the CVJ, were examined in the experimental animals [9], in the post mortem human samples [2], in certain digital models [31,37], and in healthy volunteers using the radiographs, computed tomography (CT), and the kinematic magnetic resonance imaging (MRI) method, but not the multislice CT (MSCT) [8,12,19,20,22,24,31,34].…”

“…Flexion and extension of the cervical spine, including the CVJ, were examined in the experimental animals [9], in the post mortem human samples [2], in certain digital models [31,37], and in healthy volunteers using the radiographs, computed tomography (CT), and the kinematic magnetic resonance imaging (MRI) method, but not the multislice CT (MSCT) [8,12,19,20,22,24,31,34]. The flexion and extension were also examined in the patients with certain degenerative diseases, tumours, or traumatic injuries of the cervical spine [6,11,17,21].…”