Dural Mobility – The Reciprocal Tension Membrane

The existence of the membranes around the brain and spinal cord is well documented in anatomic research and utilized in medical practice. This entire membranous envelope functions as a unit and is called the Reciprocal Tension Membrane (RTM).

Every medical student and anatomist who has dissected the central nervous system has seen this membrane. Every physician who has performed a lumbar puncture (spinal tap) has felt the “pop” as the needle penetrates the dural membrane to sample Cerebrospinal Fluid (CSF).

  • Kostopoulos and Keramidas1 in their research on cadavers, suggest that there is an association between treatment of the cranial bones and the movement of cranial dural membranes.
  • Zanakis et al.2 identified a possible connection between cranial and sacral motion. Cranial bone motion was recorded via Infrared skin markers positioned on the subject’s head with simultaneous palpation of the sacrum. A 92% correlation between the perception of sacral movement and cranial bone motion was demonstrated. Given the relatively small number of subjects, larger follow up studies need to be performed to establish statistical significance.


There is no doubt as to the existence of the continuity of dural membranes around the central nervous system (brain and spinal cord). Over 75 years of effective clinical application of Osteopathy in the Cranial Field (OCF) leaves little question as to the validity of this phenomenon. Due to the small number of studies, further research is prudent.


  1. Kostopoulos DC, Keramidas G. Changes in elongation of falx cerebri during craniosacral therapy techniques applied on the skull of an embalmed cadaver. J Craniomand Pract 1992;10:9-12.
  2. Zanakis MF, Dimeo J, Madoma S, et al. Objective measurement of the CRI with manipulation and palpation of the sacrum [abstract]. J Am Osteopath Assoc 1996;96(9):55.