Anatomic, functional, and radiographic review of the ligaments of the craniocervical junction

Abstract

The craniocervical junction (CCJ) is a complex and unique osteoligamentous structure that balances maximum stability and protection of vital neurovascular anatomy with ample mobility and range of motion. With the increasing utilization and improved resolution of cervical magnetic resonance imaging, craniocervical injury is being more accurately defined as a spectrum of injury that ranges in severity from overt craniocervical disassociation to isolated injuries of one more of the craniocervical ligaments, which may also lead to craniocervical instability. Thus, it is vital for the radiologist and neurosurgeon to have a thorough understanding of the imaging anatomy and function of the CCJ.

Keywords: Craniocervical junction; magnetic resonance imaging; trauma.

Figure 1

Sagittal illustration demonstrating the major craniocervical ligaments, including the tectorial membrane (blue), anterior atlanto-occipital membrane, apical ligament, cruciform ligament (superior and inferior longitudinal bands and transverse bands), and posterior atlanto-occipital membrane and their relationship with surrounding ligaments, skull base, and bony anatomy of the cervical spine

Figure 2

Axial illustration demonstrating the deep ligaments of the craniocervical junction, including the tectorial membrane (cut), transverse band of the cruciate ligament, and alar ligaments and their anatomic relationship with the brainstem and vertebral arteries

Figure 3

Coronal, anterior illustration demonstrating the ligaments of the craniocervical junction including the tectorial membrane (cut), cruciate ligament, alar ligament, apical ligament, and posterior longitudinal ligament

Figure 4

(a) Sagittal, midline T2 weighted image of the cervical spine demonstrating the anterior atlanto-occipital membrane (red dashed arrow), apical ligament (red arrow), superior longitudinal band of the cruciform ligament (white dashed arrow), tectorial membrane (white arrow), and posterior atlanto-occipital membrane complex, including the posterior atlanto-occipital membrane (blue arrow) and posterior atlanto-axial membrane (blue dashed arrow). (b) Parasagittal T2 weighted image of the cervical spine demonstrating the longus capitis muscle (red star) inserting on the skull base, the alar ligament (white arrow) inserting on the occipital condyle, and the posterior atlanto-occipital membrane (white dashed arrow). Clinical images were obtained from imaging studies performed at our institution. No patient identifying information was included

Figure 5

Axial T2 medic (a) and T2 weighted sequence (b) through C1-C2 level demonstrating the transverse band of the cruciform ligament (red arrows) coursing posterior to the dens and inserting on the inner cortex of the anterolateral C1 arch. The cruciform ligament is the major stabilizing ligament of the atlantoaxial joint. Clinical images were obtained from imaging studies performed at our institution. No patient identifying information was included