Cranial Osteopathy & SBS Dysfunctions

Primary respiratory mechanism, sphenobasilar synchondrosis (SBS) strains.

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◆Primary respiratory mechanism (PRM) — 5 components (Sutherland)

•10–14 cycles/minute (some sources 6–12)
•Flexion phase: midline bones flex, paired bones externally rotate
•Extension phase: midline bones extend, paired bones internally rotate
•Sacral motion: 'craniosacral mechanism' — sacrum counter-nutates with cranial flexion

•TORSION: sphenoid and occiput rotate in OPPOSITE directions around an AP axis. Named for the side of the HIGH greater wing of sphenoid (e.g., 'right torsion' = R greater wing high)
•SIDE-BENDING ROTATION: sphenoid and occiput rotate in SAME direction around an AP axis, but ALSO side-bend at a vertical axis. Bones go away from midline on the side of the convexity. Named for side of CONVEXITY (where greater wing and occipital squama are LOW)
•VERTICAL STRAIN: sphenoid base moves superiorly (superior vertical strain) or inferiorly (inferior vertical strain) relative to occiput — they remain in parallel planes
•LATERAL STRAIN: sphenoid translates laterally relative to occiput; both axes are vertical and parallel; named for the side of the sphenoid base translation (e.g., 'right lateral strain' = sphenoid moved right)
•COMPRESSION: sphenoid and occiput compressed together; no motion sensed; often after head trauma; commonly associated with depression, severe headache

•Vault hold: hands cradle the cranium with index on greater wings of sphenoid
•Listen for cranial rhythm and the type of motion
•Distinguishing torsion vs side-bending rotation: in torsion, one greater wing is HIGH while the SAME-SIDE occipital squama is LOW (opposite); in side-bending, the LOW greater wing and LOW occipital squama are on the SAME side (the convexity)

•Indirect (most common): exaggerate the strain pattern, hold until still point, allow inherent forces to correct
•CV4 (compression of 4th ventricle): operator's thenar eminences engage occiput, gentle compression to enhance CSF flow; used for sinusitis, headache, fever, autonomic balancing
•V-spread (frontal lift, parietal lift): spreading sutures
•Indications: tension headaches, sinusitis, otitis media, post-concussion, infants with plagiocephaly, asymmetry from birth trauma
•Contraindications: acute intracranial bleed, increased ICP, recent skull fracture, severe coagulopathy

Strain	Sphenoid/Occiput motion	Named for	Key finding
Torsion	Opposite direction (one wing up, other down)	Side of HIGH greater wing	High wing + LOW same-side occipital squama
Side-bending rotation	Same direction + side-bend	Side of CONVEXITY (low wing + low squama same side)	Bones bulge away on convex side
Vertical strain	Sphenoid moves sup or inf parallel to occiput	Direction of sphenoid base	Superior or inferior strain
Lateral strain	Sphenoid translates left or right	Side of sphenoid base translation	Parallel vertical axes shifted
Compression	Squeezed together; no motion	—	Often post-trauma; severe headache, depression

◆Cranial rhythm 10–14 cycles/min — independent of breathing
◆All paired bones in cranium: external rotation in flexion phase
◆CV4 enhances CSF flow — useful for autonomic balancing, tension headaches, sinusitis
◆Compression of SBS often follows head trauma and presents with depression + severe headache
◆Contraindications: acute intracranial bleed/↑ICP, recent skull fracture

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