Why is posterior disc herniation less common in the cervical region?

Why is posterior disc herniation less common in the cervical region?

• A. The cervical PLL is thinner, allowing herniation
• B. The cervical PLL is thicker in the cervical region and has strong disc attachments that prevent herniation
• C. There are more nerve roots in the cervical region
• D. The cervical discs lack an annulus fibrosus

Answer: (B)

Posterior disc herniation is less common in the cervical spine because the posterior longitudinal ligament here is thick and tightly anchored to the vertebral bodies and to the disc itself, forming a strong barrier against posterior extrusion of disc material. This robust barrier makes it harder for a fragment to push directly backward into the spinal canal, so shearing or bulging tends to occur more laterally where the PLL is thinner or less firmly attached. In regions with a thinner PLL or weaker disc attachments, posterior or posterolateral herniations are more likely. For context, discs in cervical regions do have an annulus fibrosus, so the idea that they lack one isn’t correct, and the number of nerve roots doesn’t determine where a disc herniates.

Posterior disc herniation is less common in the cervical spine because the posterior longitudinal ligament here is thick and tightly anchored to the vertebral bodies and to the disc itself, forming a strong barrier against posterior extrusion of disc material. This robust barrier makes it harder for a fragment to push directly backward into the spinal canal, so shearing or bulging tends to occur more laterally where the PLL is thinner or less firmly attached. In regions with a thinner PLL or weaker disc attachments, posterior or posterolateral herniations are more likely. For context, discs in cervical regions do have an annulus fibrosus, so the idea that they lack one isn’t correct, and the number of nerve roots doesn’t determine where a disc herniates.