Magnetic resonance imaging anatomy of the craniovertebral ligaments: A radiological study with confirmatory dissection

BACKGROUND: Descriptions of the radiological appearance of the craniovertebral ligaments often lack detail. This study aimed to provide an accurate description of the morphology and radiological appearance of the alar and cruciform ligaments with confirmation of findings by fine dissection. MATERIALS AND METHODS: Six embalmed human cadaveric specimens were reduced to an osseoligamentous arrangement spanning the C2/3 disc to the occiput. Specimens were imaged on a 4.6T Bruker magnetic resonance (MR) system using a 3D RARE multiple SE sequence with acquisition time 18 h 24 min. Acquired images were viewed in three planes, and detailed descriptions and morphometric measurement of the ligaments were obtained. Specimens were then examined and described using fine dissection. Direct comparison of the descriptions of each method was undertaken. RESULTS: From imaging, detailed features of all alar ligaments could be identified in all specimens. Consistency in shape, orientation, and attachments is described. Attachment to the medial aspect of the atlantooccipital joints was evident in all specimens. Five of six alar ligament pairs contained fibers that traversed the dens without attachment. Ascending cruciform ligaments could be clearly identified in four of six specimens. No descending cruciform ligaments could be clearly delineated. Detailed features of the transverse ligaments could be identified and described in all planes. Dissection findings were mostly consistent with descriptions obtained from MR images. CONCLUSION: 4.6T MR images provide accurate detail of the structure, dimensions, and attachments of the craniovertebral ligaments. The morphology of the craniovertebral ligaments assessed radiologically was consistent with findings on gross dissection.