Morphometric analysis of the uncinate processes of the cervical vertebrae

Background: Uncinate processes (UPs) are distinct features unique to cervical vertebrae. They are consistently found on posterolateral aspect of the superior end plate of 3rd to 7th cervical vertebrae. In this study, we investigated the morphology of the UPs with a particular emphasis on the regional anatomy and clinical significance. Materials and methods: The study included 63 vertebrae. The width, height and length of UPs were measured with a digital calliper. We also assessed inclination angle of UP relative to sagittal plane, angle between medial surface of UP and superior surface of vertebra, angle between long axis of the UP and frontal plane, angle between long axis of UP and sagittal plane. Results: Average width of the UPs ranged from 4.25 mm at C3 to 6.33 mm at T1; average height ranged from 4.88 mm at T1 to 7.54 mm at C4; and average length ranged from 6.88 mm at T1 to 11.46 mm at C4. We measured the inclination angle of UP relative to sagittal plane, and found it to be relatively constant with T1 having the largest value. The average angle was 41.39 degrees, and the range was 17 degrees to 85 degrees. The angle between the long axis of the UP and the sagittal plane was increasing significantly from C5 to T1. The average angle was 20.74 degrees and the range was 6 degrees to 65 degrees. Conclusions: Anatomy of UPs is significant for surgeon who operates on the cervical spine. Hopefully, the information presented herein would decrease complications during surgical approaches to the cervical spine.