Lecture #11: OMM: Introduction to Osteopathy in the Cranial Field

Who developed the Cranial Concept in osteopathy?

William Garner Sutherland, DO, developed the Cranial Concept after studying osteopathy under A.T. Still and examining the structure of cranial sutures.

How did the Cranial Concept originate?

Sutherland observed the beveled articular surfaces of the sphenoid and reasoned that their structure suggested motion, consistent with Still's principle that function can be deduced from structure.

How did Sutherland view the relationship between the Cranial Concept and osteopathy?

He taught that the cranial concept was not separate from osteopathy, but rather an extension of the same osteopathic science and philosophy.

What did A.L. Wales say Sutherland contributed to osteopathy?

Sutherland "helped complete the osteopathic concept by adding the head to the rest of the body."

What is the Primary Respiratory Mechanism (PRM)?

An inherent, involuntary, rhythmic motion of the body involving the nervous system, cerebrospinal fluid, dural membranes, cranial bones, and sacrum.

Is the PRM voluntary or involuntary?

It is an involuntary motion that can be palpated and used diagnostically and therapeutically.

What are the five phenomena of the Primary Respiratory Mechanism?

Inherent motility of the brain and spinal cord, fluctuation of cerebrospinal fluid, mobility of the dural membranes, mobility of the cranial bones, and involuntary mobility of the sacrum.

What is the inherent motility of the brain and spinal cord?

An intrinsic spontaneous motion of the nervous system that is synchronized with the phases of the PRM.

What is meant by fluctuation of cerebrospinal fluid?

A to-and-fro movement of CSF within its natural cavities that is observed by palpation and works together with circulation.

What is the "potency of the Tide" in the lecture?

Sutherland's concept of an inherent force associated with CSF fluctuation that contributes to its movement.

What is the mobility of the dural membranes?

The dural membranes move as a reciprocal tension membrane, guiding and limiting motion of the cranial bones.

What is the mobility of the cranial bones?

Small physiologic motion occurring at cranial sutures that accommodates the alternating shape changes of the PRM.

What is the involuntary mobility of the sacrum?

Motion of the sacrum transmitted through the spinal dura as part of the PRM.

How can the five phenomena of the PRM be conceptualized?

As a container—the cranium and membranous support—and contents—the brain and cerebrospinal fluid; dysfunction of the container can influence the function of the contents.

What happens to the cranial shape during the inhalation phase of the PRM?

The cranium widens transversely and narrows in the anteroposterior and vertical dimensions.

What happens to the cranial shape during the exhalation phase of the PRM?

The transverse diameter narrows while the anteroposterior and vertical dimensions increase.

What term describes the inhalation phase of midline cranial bones?

Flexion.

What term describes the exhalation phase of midline cranial bones?

Extension.

How do paired cranial bones move during inhalation?

They undergo external rotation during flexion/inhalation.

How do paired cranial bones move during exhalation?

They undergo internal rotation during extension/exhalation.

Does the cranial vault change volume during the PRM?

No. The lecture emphasizes an alternating change in shape, not an overall change in cranial volume.

How do midline cranial bones move during the PRM?

They rotate around transverse axes, with adjacent bones moving in opposite directions in a gear-like fashion.

What happens at the sphenobasilar junction during flexion?

The sphenobasilar junction moves superiorly.

What happens at the sphenobasilar junction during extension?

The sphenobasilar junction moves inferiorly.

What does the sagittal suture demonstrate about cranial mobility?

Its serrate, interlocking structure allows a rocking motion that accommodates widening of the parietal bones.

What does the squamous suture demonstrate about cranial mobility?

Its overlapping structure permits gliding motion that accommodates increases and decreases in transverse cranial diameter.

What is the significance of sutural anatomy in the Cranial Concept?

The shape and design of cranial sutures are interpreted as structures capable of accommodating small physiologic movements.

Are all cranial sutures fully ossified in older adults?

No. The lecture notes studies identifying unossified sutures even in elderly cadavers, with ligamentous and neurovascular structures still present.

How does the cranial base differ from the cranial vault developmentally?

The cranial base develops largely in cartilage, while much of the cranial vault develops in membrane.

Which bones are emphasized as part of the cranial base?

The petrous temporal bones, sphenoid body, and occiput below the superior nuchal line.

Which bones are emphasized as part of the cranial vault?

The parietals, frontals, squamous temporal bones, and occiput above the superior nuchal line.

Where did Sutherland teach that true articular mobility primarily occurs?

In the cranial base, while motion in the vault is considered accommodative to motion of the base.

What term did Sutherland use for cranial lesions?

Membranous articular strains.

Why did Sutherland call cranial lesions membranous articular strains?

Because cranial dysfunction involves both the intracranial membranes and the cranial articulations.

What is the reciprocal tension membrane?

The intracranial dural membrane system that guides and limits cranial bone motion while maintaining balanced tension.

Which dural structures form the major reciprocal tension membrane?

The falx cerebri and tentorium cerebelli.

What is the functional role of the dural membranes in cranial motion?

They act like check ligaments, guiding and limiting the motion of cranial bones.

What is the dural fulcrum?

An imaginary central point around which the reciprocal tension membrane operates; the lecture places it somewhere along the straight sinus.

Where does the falx cerebri attach?

The lecture emphasizes attachments to the occiput and ethmoid.

Where does the tentorium cerebelli attach?

The lecture emphasizes attachments to the occiput, temporal bones, and sphenoid.

How does the dura relate to the cranial base?

The dura attaches to each of the bones of the cranial base and functions like a ligamentous system that guides and limits their motion.

What is the "core link"?

The spinal continuation of the dura connecting the occiput to the sacrum and linking sacral motion to the PRM.

What are the major dural attachments of the core link?

The lecture describes firm attachments at the foramen magnum, C2, C3, and S2.

How does the sacrum move during flexion/inhalation?

The sacrum moves into counternutation, with the sacral base moving posteriorly.

How does the sacrum move during extension/exhalation?

The sacrum moves into nutation.

How do the falx and tentorium move during the PRM?

They move with large arcing, sickle-like motions during inhalation and exhalation.

How does nervous-system motion relate to embryologic development?

The nervous system begins as a hollow neural tube and develops by coiling; this developmental pattern is reflected in its intrinsic PRM motion.

What happens to the CNS during the inhalation phase of the PRM?

The nervous system coils, becoming shorter and broader or fatter.

What happens to the CNS during the exhalation phase of the PRM?

The nervous system uncoils, reversing the coiling pattern seen during inhalation.

How does CSF circulation differ from CSF fluctuation?

Circulation is movement from one region to another, such as from the choroid plexus toward arachnoid granulations, whereas fluctuation is a to-and-fro movement within the fluid system.

Where is CSF produced and where is it absorbed according to the lecture?

It is produced at the choroid plexus and ultimately empties into the venous sinuses through the arachnoid granulations.

What is the major overall conclusion of the lecture regarding the PRM?

The PRM is an inherent, involuntary, rhythmic alternating motion present throughout the body and expressed through tissue mobility, fluid fluctuation, nervous-system motility, and craniosacral motion; although subtle, it is considered palpable and clinically informative.