Known as the cranial keystone, the sphenoid bone is one of the most mysterious parts of our anatomy. Associated with many common health problems, a restricted sphenoid can be freed by cranial-sacral therapy.
Located in the very center of the skull, the sphenoid bone is in a unique and influential position. While many allopathic physicians address a large span of health complaints associated with a restricted sphenoid, working directly with this bone is far from simple. However, learning how to effectively administer cranial-sacral therapy affords health practitioners this seemingly challenging feat. Since its official assimilation into complementary medicine in the 1970s, bodyworkers trained in cranial-sacral therapy have been able to create many healing opportunities by gently manipulating this cranial bone.
Named for its wedge-like butterfly shape, the sphenoid is a prominent, irregularly shaped bone at the base of the skull. Because it is in contact with all of the other cranial bones, the sphenoid is often referred to as the “keystone” of the cranial floor.
The sphenoid has a number of features and projections, requiring a student to study it from various perspectives to fully appreciate its form. This single bone runs through the mid-sagittal plane and helps connect the cranial skeleton to the facial skeleton. The sphenoid articulates posteriorly with the occipital bone, laterally with the temporal and parietal bones, and anteriorly with the frontal and ethmoid bones. It consists of a hollow body, which contains the sphenoidal sinus, and three pairs of projections:
The more superior lesser wings
The intermediate greater wings
The most inferior projecting pterygoid processes
The anterior surface of the great wings forms most of the posterior walls of the orbital cavities. The optic foramina, located in the bases of the small wings, provide for the passage of the optic nerves from the eyes to the base of the brain. The superior surface of the body of the sphenoid contains a deep depression housing the pituitary gland, called the sella turcica, or Turk’s saddle. In addition, the plentitude of surfaces and articulations of the sphenoid harbor the passage of:
The ophthalmic artery into the orbital cavity
The third, fourth, fifth and sixth cranial nerves from the brain into the orbital cavity
The maxillary division of the fifth cranial nerve
The mandibular division of the fifth cranial nerve
The middle meningeal blood vessels
Separated by a bony septum projecting downward into the nasal cavity, the sphenoid bone also contains two sinuses, which lie side by side. The most common way for allopathic medical practitioners to access the sphenoid bone is through the nasal passages.
Cranial-sacral therapy was first taught to other osteopaths by William Sutherland, DO, in the 1930s, based on the theories and techniques learned while attending the American School of Osteopathy. It was there Dr. Sutherland realized the cranial bones allow for small amounts of movement driven by the flow of cerebrospinal fluid (CSF). Identified as a wave-like motion, the cranial-sacral rhythm carries CSF up and down the spine and around the brain. Despite it being tethered in many different planes, the non-stationary sphenoid bone plays an active role in the circulation of CSF. Within the brain, the cranial pumping mechanism known to circulate the CSF occurs where the sphenoid bone articulates with the basilar portion of the occiput bone.
With each breath we take, the nasal conchae fill up with air, which applies pressure on the anterior portion of the sphenoid bone and the sphenoidal sinus where it contacts the basilar portion of the occiput bone. This pressure causes the spheno-basilar junction to move slightly posterior and inferior. On expiration, the spheno-basilar articulation relaxes as the pressure created by the inhaled air is exhaled. This release of pressure causes the spheno-basilar junction to move slightly anterior and superior. These movements of the spheno-basilar junction are believed to drive the cranial-sacral rhythm. This rhythm pumps CSF down through the spinal canal on its journey around the spine, sacrum and back up to the cranium.
In cranial sacral theory, the terms respiration and pulse have meanings separate from general anatomy terminology. There are two respiration phases: primary and secondary. Primary respiration itself has two phases, inhalation and exhalation, and refers to the more subtle metabolism or physiological respiration that continues for a few hours after death. Secondary respiration refers to the physical movement of the rib cage during the breathing in/out process. In life they operate in unison, as described in the above paragraph.
The movement between the sphenoid and the occiput has long been considered a primary focus in cranial therapeutics. In the osteopathic model developed by Dr. Sutherland and later presented in books by Magoun and Upledger, the following movements occur between the sphenoid and occiput near or at the sphenobasilar junction:
Torsion (Right and Left)
Side-Bending (Right and Left)
Vertical Strain (Superiorly and Inferiorly)
Lateral Strain (Right and Left)
Problems Associated With the Sphenoid
Medical professionals often perceive the keystone of the cranial floor as off-balance or restricted in its movement. When the structure deep inside the skull is not moving freely, there can be many repercussions. As a direct or indirect result of hindered CSF flow, an inhibited sphenoid bone can cause many conditions. Below are 18 ailments often associated with a restricted sphenoid:
Dental or TMJ Problems
Eye Problems, Including Visual Disturbances
Tinnitus and Middle Ear Problems
Headaches or Migraines
How Bodyworkers Can Readjust the Sphenoid
While specially trained physicians aim to reset an unbalanced sphenoid bone by inserting specialized instruments up both nasal cavities, these techniques are beyond a bodyworker’s scope of practice. Luckily, cranial-sacral therapy accomplishes this same task through a non-invasive, extremely gentle application.
Bodyworkers trained in cranial-sacral therapy can free the sphenoid from any restrictions, by applying point and direction specific pressure on the cranium. Equivalent to the weight of a nickel, this pressure is barely perceptible to the recipient of the therapy.
Because it articulates with all of the other cranial bones and its movement is responsible for circulating the CSF, the sphenoid bone is one of the primary foci of cranial-sacral adjustments. Understanding the complex, 3-dimensional anatomy of this bone can help bodyworkers practicing cranial-sacral therapy better visualize their work. Through their influence over this cranial keystone, bodyworkers who include this method are in the best position to help clients recover from a long list of undesirable ailments.
http://www.osteohome.com/SubPages/5phenom.html, The Five Phenomena of the Primary Respiratory System, Osteopathic Educational Services, 2011
http://www.acornseminars.com/history.history.html, History of Craniosacral Therapy, Regina Green, Acorn Seminars, Inc., 2011
http://education.yahoo.com, The sphenoid bone, Bartelby.com, 2008.
Spence, Alexander P., Basic Human Anatomy – Third Edition, The Benjamin/Cummings Publishing Company, Inc., Redwood City, CA, 1990.
http://www.integrativehealthcare.org/mt/archives/2010/08/bodyworkers_can_2.html, Bodyworkers Can Influence the Cranial Keystone, Nicole Cutler L.Ac. August 18th, 2010