Abstract:

Objective To explore the anatomic cause of the epidural cervical disc extrusion (ECDE) by observing the morphology of cervical posterior longitudinal ligament(PLL) and anterior intervertebral venous plexus under surgical microscope and light microscope. Methods Whole cervical spinal columns from C2 to C7 were collected from 10 formalin-fixed human adult cadavers of Chinese origin.In 10 columns,the block laminectomy was done.The layers,orientation and distribution of the cervical PLL were observed and the cervical anterior intervertebral venous plexus was observed under surgical microscope and light microscope. Results The cervical PLL was made up of three layers.There were the fibers of superficial layer on the back of the vertebral bodys across several intervertebral spaces.The superficial layer were divided into two portions,logitudinal and oblique fibers.The logitudinal fibers covered on the back central section of the intervetebral disk annulus fibrosus.The deep fibers exposed from the back lower edge of one vertebral body to the back superior edge of inferior adjacent vertebral body,covering on the back of the intervertebral disk.Between the superficial fibers and the deep fibers, there were the middle part of longitudinal fibers,which crossed a single disc,arising from the bottom bone of one vertebral body veins hole,inserting in the top bone of the inferior adjacent vertebral veins hole.All of the three layers coverd over the back middle part of the posterior annulus fibrosus,otherwise there were only two layers covering on the back lateral-middle part of the posterior annulus fibrosus.The cervical anterior intervertebral venous plexus was embedded between the superficial and deep layers of the cervical PLL in the lateral-middle area on the back of the cervical intervertebral disc which was relatively weaker than the middle area. Conclusion There is a weak area behind the paracentral area side of the cervical intervertebral disc,which may constitute a part of anatomic factors producing ECDE.Understanding the vertebral venous plexus anatomical features could help clinical doctors control intraoperative bleeding and reduce the rate of nerve damage.

Key words: cervical spine, disc extrusion, epidural, posterior longitudinal ligament, anterior intervertebral venous plexus