title: The diameters and number of nerve fibers in spinal nerve roots.
abstract: OBJECTIVE
  To investigate the anatomical and histological features of spinal nerve roots and provide base data for neuroanastomosis therapy for paraplegia.
  
  
  METHODS
  Spinal nerve roots from C1 to S5 were exposed on six adult cadavers. The diameter and the number of nerve fibers of each nerve root were measured, respectively, with a caliper and image analysis software.
  
  
  RESULTS
  As for ventral roots, the diameter of C5 (2.50 ± 0.55 mm) was the largest in cervical segments. In thoracic and lumbosacral segments, the diameter gradually increased from T11 to S1 and then decreased from S1 to S5 except L3. S1 (1.43 ± 0.16 mm) was the thickest root and S5 (0.14 ± 0.02 mm) was the thinnest one. As for dorsal roots, the diameter of C7 (4.61 ± 0.87 mm) was the largest in cervical segments. From T11 to S1, the diameter increased and then decreased gradually from S1 to S5. The diameter of dorsal roots from T1 to S5 was largest at S1 (2.95 ± 0.57 mm) and smallest at S5 (0.27 ± 0.13 mm), respectively. C7 (8467 ± 1019), T12 (6538 ± 892), L3 (9169 ± 1160), and S1 (8253 ± 1419) ventral roots contained the most nerve fibers in cervical, thoracic, lumbar, and sacral segments, respectively. Similarly, C7 (39 653 ± 8458), T1 (26 507 ± 7617), L5 (34 455 ± 2740), and S1 (41 543 ± 3036) dorsal roots, respectively, contained the most nerve fibers in their corresponding segments.
  
  
  CONCLUSIONS
  The findings in the current study provided the imperative data and may be valuable for spinal nerve root microanastomosis surgery in the paraplegic patients.
authors.forename: YongTao
authors.initials: Y
authors.lastname: Liu
authors.forename: XiaoJi
authors.initials: X
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.forename: YingBin
authors.initials: Y
authors.lastname: Ge
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Cao
mesh_terms: D000328:Adult; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D009412:Nerve Fibers / Q000648:ultrastructure*; D013126:Spinal Nerve Roots / Q000033:anatomy & histology*
keywords: Anastomosis; Nerve transfer; Paraplegia; Spinal cord injuries; Spinal nerve roots