Analysis of the uncinate processes of the cervical spine: an anatomical study

Laboratory investigation

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Although the uncovertebral region is neurosurgically relevant, relatively little is reported in the literature, specifically the neurosurgical literature, regarding its anatomy. Therefore, the present study aimed at further elucidation of this region's morphological features.


Morphometry was performed on the uncinate processes of 40 adult human skeletons. Additionally, range of motion testing was performed, with special attention given to the uncinate processes. Finally, these excrescences were classified based on their encroachment on the adjacent intervertebral foramen.


The height of these processes was on average 4.8 mm, and there was an inverse relationship between height of the uncinate process and the size of the intervertebral foramen. Degeneration of the vertebral body (VB) did not correlate with whether the uncinate process effaced the intervertebral foramen. The taller uncinate processes tended to be located below C-3 vertebral levels, and their average anteroposterior length was 8 mm. The average thickness was found to be 4.9 mm for the base and 1.8 mm for the apex. There were no significant differences found between vertebral level and thickness of the uncinate process. Arthritic changes of the cervical VBs did not necessarily deform the uncinate processes. With axial rotation, the intervertebral discs were noted to be driven into the ipsilateral uncinate process. With lateral flexion, the ipsilateral uncinate processes aided the ipsilateral facet joints in maintaining the integrity of the ipsilateral intervertebral foramen.


A good appreciation for the anatomy of the uncinate processes is important to the neurosurgeon who operates on the spine. It is hoped that the data presented herein will decrease complications during surgical approaches to the cervical spine.

Abbreviations used in this paper:AP = anteroposterior; VB = vertebral body.

Article Information

Address correspondence to: R. Shane Tubbs, M.S., P.A.-C., Ph.D., Section of Pediatric Neurosurgery, Children's Hospital, 1600 7th Avenue South, ACC 400, Birmingham, Alabama 35233. email:

Please include this information when citing this paper: published online January 20, 2012; DOI: 10.3171/2011.12.SPINE11541.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Schematic drawing of the cervical vertebrae illustrating the relationships between the uncinate processes (arrows) and intervertebral foramina, with associated nerves.

  • View in gallery

    Photograph of a Type I uncinate process. Note that the uncinate process (U) does not encroach upon the adjacent intervertebral foramen.

  • View in gallery

    Photographs of a Type II uncinate process; lateral (upper) and anterior (lower) views. Note deformation of the uncinate process, with encroachment into the adjacent intervertebral foramen.

  • View in gallery

    Photograph of a Type III uncinate process. Note that there is no deformation of the uncinate process, but encroachment into the adjacent intervertebral foramen.

  • View in gallery

    Left: Photograph of an articulated cervical spine (neutral position), with artificial intervertebral discs in place. Right: The same spine in right lateral flexion; note the relationship created between the adjacent discs and uncinate processes.

  • View in gallery

    Reconstructed 3D CT of the head and upper spine, noting the normal appearance of the right uncinate processes (arrows).



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