Spinal Cord Meninges
Ovid in shape, the spinal cord originates at the top from the medulla oblongata at the base of the brain and extends down to the space in between the first and second of the lumbar vertebrae to an area called the filum terminale. The dura mater (see image below) forms the outermost layer of the spinal cord and provides a protective shield to prevent compression and injury. The space between the dura mater and the vertebral bone is the epidural space which is filled with fatty tissue and contains blood vessels. This is the area in which epidural steroid injections are administered in order to not penetrate the spinal cord or its meninges directly, but to instead allow the anti-inflammatory and analgesic drugs to diffuse across these membranes.
Spinal Cord Meninges Protection
The dura mater is just one of the three meninges, or layers of tissue, that protect the spinal cord. Beneath the dura mater is the arachnoid mater which has a web-like appearance and is separated from the inner meninge by the subarachnoid space. This is where the cerebrospinal fluid is contained, and is where a lumbar puncture taps fluid in order to test for the presence of disease, infection, or inflammation. The inner meninge is the pia mater, which is the most delicate of the membranes and is almost contiguous with the spinal cord itself.
From the pia mater, between the dorsal and ventral roots, there are connecting denticulate ligaments which serve to stabilize the spinal cord within the dura mater. The spinal cord has two grooves running its length, one on the dorsal side and one on the ventral side called the median sulcus and the anterior median fissure respectively.
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