Spinal dura

The spinal dura mater is the protective dura mater membrane surrounding the spinal cord. It’s an extension of the inner meningeal layer of the cranial dura mater that continues down to cover the spinal cord after it passes through the foramen magnum. The outer layer of the cranial dura mater, that covers the brain, becomes the periosteum and doesn't extend to cover the spinal cord.

As the spinal dura mater envelops the spinal cord, it connects with the epineurium of the spinal nerves when they emerge through the intervertebral foramina. Inside, it joins with the triangular extensions of the pia mater, known as the denticulate ligaments, providing horizontal support to the spinal cord within the cerebrospinal fluid.

Even though the spinal cord ends at the first lumbar (L1) vertebra in adults, the meningeal coverings continue down the vertebral column, with the arachnoid and dura mater ending at the second sacral (S2) vertebra. The space between L1 and L3 vertebrae is significant for lumbar punctures.

The epidural and subdural meningeal spaces associated with the cranial dura mater also extend into the spinal cord region, forming the spinal epidural and subdural spaces. The spinal epidural space contains important structures like epidural fat, veins, and arteries. This space is crucial in administering epidural anesthesia during childbirth.