Microsurgical Anatomy of the Lower Cervical Spine and Cord

Abstract

The authors dissected the cervical spine and its surrounding structures from 40 adult cadavers under a surgical microscope. The anterior part of the spine and spinal cord was examined after vertebrectomy. The posterior longitudinal ligament (PLL) consists of two layers; the anterior one is termed the deep layer, and the posterior one is termed the superficial layer. These two layers adhered together loosely. In the lateral portion of the spinal canal, the superficial layer joined the periradicular sheath at the level of the intervertebral disc spaces and joined the dura mater at the level of the vertebral bodies. After the removal of the deep layer, the anterior internal vertebral venous plexus was seen on top of the lateral part of the superficial layer. The venous plexus was embedded between the double-layered PLLs, was not located in the epidural space, and was not seen in the medial part of the PLL. The PLL without venous channels on top of it was about 10 mm in width at the levels of the intervertebral disc and about 5 mm at the levels of the vertebral body. The anterior root exit zone (AREZ) was an elliptical shape; the transverse length of the AREZ was about 2 mm, and the longitudinal length was 10 to 15 mm. The average number of anterior rootlets on the AREZ was 17 to 25 and tended to decrease in the lower cervical spinal cord. The posterior structures were examined after en bloc laminectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

A cadaveric study of the cervical nerve roots and spinal segments

“…Furthermore, the width of C7 on the dorsal side was also significantly narrower than these nerve roots. Therefore, our findings are consistent with the results of Shinomiya et al [6] However, regarding the occurrence of radiculopathy, we should therefore consider not only the width of the nerve root, but also the relationship to the surrounding bony anatomy. To our knowledge, no previous reports have described the relationship between the width of each cervical nerve root and the spinal segment.…”

“…Regarding the width of the spinal segment, we found some previous papers [5][6][7] describing this issue. For [6] investigated the width of the spinal segment from C5 to C8 using cadavers and noted that the width of the C6 was the widest, while that of C8 was the narrowest, and that the widths of C5 and C6 were significantly wider than those of C7 and C8.…”

“…For [6] investigated the width of the spinal segment from C5 to C8 using cadavers and noted that the width of the C6 was the widest, while that of C8 was the narrowest, and that the widths of C5 and C6 were significantly wider than those of C7 and C8. Karatas et al [5] also measured the widths from C2 to C8 using cadavers and found that the longest longitudinal length was at the C5 level, while the shortest was at the C2 level.…”

Microsurgical anatomy of the dorsal thoracic rootlets and dorsal root entry zones

“…In fact, the most frequent complications of DREZ surgery at the thoracic level are ipsilateral leg weakness and a likely reduction in bladder reflexes [14]. At each spinal segment, a few rootlets emerge to give rise to a dorsal root; the number of dorsal rootlets varies at each spinal cord segment [4,7,17,18]. Most thoracic segments give rise to 3-4 dorsal rootlets, which are fewer than those seen at the cervical and lumbosacral segments.…”

“…The dorsal rootlet entry into the posterolateral sulcus varies in accordance with the levels of the spinal cord. Although these relationships have been studied in detail for cervical, lumbar, and sacral spinal segments, such information is not available for thoracic segments [4,6,7,17,18]. Though less frequent, thoracic DREZ surgeries are performed in cases of postherpetic neuralgia, spasticity and/or pain after spinal cord injury, and pain due to malignant invasions of the thorax and abdominal wall [2,15].…”