A new anatomic zone division within the human cervical spinal canal

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background: </jats:bold>Anatomic details are important for identifying the origin and anatomic basis of symptoms in patients with cervical spondylosis. However, very little quantitative data has been reported. In an effort to provide an anatomic basis for the examination of cervical spondylosis mechanisms, we characterized the morphologic features of cervical spinal nerve rootlets and defined different zones of the human cervical spinal canal.<jats:bold>Methods: </jats:bold>In 10 cadaveric cervical cords from C2 to T1, we defined three zones bilaterally from the midline (zones I-III) and two zones from cranial to caudal (zones P and IP) on the coronal plane within the cervical spinal canal. We measured each anatomic zone, including 1) horizontal widths of zones I, II and III; 2) the length of the cervical spinal segment at the ventral rootlets (LV); 3) the pedicle height (zone P) and interpedicle height (zone IP); and 4) the distance between the superior margin of the pedicle and the exit of the uppermost ventral nerve rootlet (PN). <jats:bold>Results:</jats:bold> The horizontal widths of zone I tended to decrease gradually from C4 to C8 (<jats:italic>p</jats:italic>=0.98). The width of zone II at C4 was significantly less than that at other levels (<jats:italic>p</jats:italic>=0.008). The width of zone III increased from C4 to C8 and was significantly greater at C7 and C8 than at C4, C5, and C6 (<jats:italic>p</jats:italic>=0.032). Pedical and interpedical heights were not significantly different at different levels (<jats:italic>p</jats:italic>=0.365 and 0.240, respectively). LV values at C4 and C8 were smaller than those at C5, C6, and C7 (<jats:italic>p</jats:italic>=0.001). At C4, the uppermost ventral rootlet was at approximately the same height as the C3 pedicle, whereas at C8, the uppermost ventral rootlet was at the same level as the inferior part of the C6 pedicle. Ventral intradural intersegmental connections were found in three of 20 (15%) intersegments (two specimens).<jats:bold>Conclusions: </jats:bold>These anatomic zones may be useful for diagnosing cervical spondylosis and guiding anterior decompression surgery.</jats:p>