Denticulate Ligaments.
Denticulate Ligaments (DLs) are strands of connective tissue that suspend the spinal cord within its membrane sac, which is called the dual tube.
The dural tube is comprised of three layers of membrane surrounding the spinal cord. The membrane layer attached to the surface of the spinal cord is called the pia mater. The layer surrounding the pia mater is called the arachnoid membrane, and the layer surrounding the arachnoid membrane is called the dura mater.
DLs extend from the inner surface of the pia mater, travel through the pia mater, through the arachnoid membrane and then attach to the inner surface of the dura mater.
There are 21 pairs of DLs on the lateral aspects of the spinal cord. The first is attached to the foramen magnum. The last is attached to the conus medullaris, which is the end of the spinal cord at L1, and a small portion of the Filum Terminale (FT) beginning at the conus medullaris. The FT is a band of tissue extending from the conus medullaris to the coccyx that is made of spinal cord glial cells surrounded by pia mater.
DLs and FT shortening, twisting, bending or immobility can place adverse stress upon the spinal cord leading to neurological strain and dysfunction. Conversely, balancing the DLs and FT can decrease spinal cord stress which in turn can enhance neurological function.
DLs are fascinating components of the dural tube that seem, to me, to create a ligamentous suspension system cradling the spinal cord. Very little DL research is available.
These questions arise when I ponder and work the DLs and FT:
1) Since the spinal cord needs to move in its bony container more than the brain tissue does in its container, do the DLs provide protection and flexibility while allowing motion?
2) The dura mater of the dural tube is only one layer thick rather than the two layers within the cranium, so do the DLs create additional tube strength without compromising movement?
3) As the spinal cord moves within the spinal canal do the DLs, like thousands of tiny interlinked bungee cords, help dissipate stress and allow the spinal cord to find its most favorable position?
4) Structures that can affect the spinal cord, such as the occiput, spinal column, sacrum and coccyx, dural tube, adipose tissue within the spinal canal and nerve roots can each have restrictive patterns that in turn can distress the spinal cord. Do the DLs help to protect the spinal cord by balancing, dissipating and fine-tuning tension that is transmitted to the spinal cord?
5) Some theories suggest that there is a down and up flow of cerebrospinal fluid within the dural tube. Since the DLs separate the dural tube into anterior and posterior compartments, could that then organize the flow of cerebrospinal fluid?
I hope you’ll join me next month to explore this suspension system further. I’ll share some ideas on how to feel and work with DLs and the FT.
References:
Cramer, Gregory D., D.C., Ph.D., and Darby, Susan A., Ph.D., Basic and Clinical Anatomy of the Spine, Spinal Cord, and ANS, Second Edition, Elsevier Mosby, St. Louis, Missouri, 2005.
Sills, Franklyn, Craniosacral Biodynamics, Volume Two, North Atlantic Books, Berkeley, California, 2004.
Tubbs, Shane R., M.S., PA-C; Salter, George, Ph.D.; Grabb, M.D.; and Oakes, Jerry W., M.D. ; “The denticulate ligament: anatomy and functional significance”, J. Neurosurg: Spine / Volume 94 / April 2001.
