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Comprehensive Review Cranial Mechanics Darlene Myles D.O. Block 8 Objectives 1. Review Cranial anatomy 2. Describe the basic components of the Cranial concept 3. Describe the major axes of motion in the Cranial base and vault 4. Describe motion mechanics of the Cranium 5. Review SBS strain patterns 6. Review visual diagnosis of SBS strain patterns Primary Respiratory Mechanism (PRM) 5 Components to Model 1) Motility of CNS 2) Fluctuation of CSF 3) Mobility of intracranial / intraspinal membranes (reciprocal tension) 4) Articular mobility of cranial bones 5) Involuntary motion of sacrum between ilia 5 poles of attachment of the Dural Membrane 1. Anterior-superior pole The falx attaches to the cristi galli of the ethmoid and to the frontal crest 2. 3. 4. 5. Anterior-inferior pole The tentorium attaches to the anterior and posterior clinoid processes of the sella turcica Lateral poles The tentorium attaches to the petrous ridge of the temporal bone and the transverse ridge of the occiput Posterior pole The internal occipital protuberance (opisthion) Sacral pole The dura exits the foramen magnum attaches to C2 and then hangs loosely until it attaches to the S2 sacral segment Primary Respiratory Mechanism (PRM) • Expansion and Contraction of the CNS discussed in relation to what happens at the major keystone joint of the Cranial mechanism (The SBS) • During the expansion phase the SBS Flexes • During the Contraction Phase the SBS Extends SBS Sphenobasilar Synchondrosis Axes of Motion for Sphenoid and Occiput • AP Axis ( 1 axis) – From Nasion through SBS to Opisthion • Vertical Axes (2 axes) – Through Foramen Magnum of the Occiput – Through Body of the Sphenoid • Transverse Axes ( 2 axes) – Through Body of the Sphenoid – Just above the Jugular Process on a level with the SBS Flexion Extension Cranial Bone Motion • Each individual bone in the cranium has a predictable motion based on bevel changes • All Midline individual bones are said to either Flex or Extend around a transverse axis • All Paired bones are said to either internally rotate or externally rotate • During Flexion Phase all midline bones Flex • During Flexion Phase all paired bones Externally Rotate • During Extension phase all midline bones Extend • During Extension phase all paired bones Internally Rotate Articular … Cranial Bones - Sphenoid Transverse axis through the center of its body is in the area of the sella turcica Vertical Axis through the center of its body is in the area of the sella turcica AP Axis through the center of its body is in the area of the sella turcica AP Axis • The motion of the sphenoid occuring in the sagittal plane described as flexion and extension Flexion: – Posterior aspect of the body elevates. – The sella turcica moves anterosuperiorly. – Greater wings move forward and slightly laterally and inferiorly. – The pterygoids move posteriorly and inferolaterally. – The body expands a little as it carries the resistance of the facial bones. • Primarily influences ethmoid, vomer and facial bones Articular … Cranial Bones - Occiput Occipital Motion The occiput has physiologic motion of flexion & extension in the sagittal plane around a transverse axis, lying just above the jugular processes. Flexion - the occipital base moves superiorly - the posterior aspect moves posterior-inferiorl - the occipital condyles move anteriorly. The occiput primarily influences the parietals & temporal bones. Articular … Cranial Bones – Temporal • • • • The motion of the occiput is directly responsible for the motion of the temporal bones. The axis of physiologic motion runs from the jugular surface to the petrous apex parallel to the petrous ridge. In the flexion phase, the temporal bones externally rotate. The squama moves anterolaterally and the mastoid portion moves medially and slightly posteriorly. In the extension phase, the reverse occurs External Rotation Internal Rotation Articular Mobility of Cranial Bones Articular … Cranial Bones - Frontal Axis of rotation runs from the center of the orbital plate up through the center of the orbital eminence near the change of bevel at the cranial border. Hinge-like action along the metopic suture, remains a line of persisting flexibility. In external rotation, the inferior lateral angles (zygomatic angles) of the frontal bone move laterally, inferiorly and slightly forward. The opposite occurs in internal rotation. – The glabella tends to recede slightly in external rotation due to the pull of the falx cerebri. Articular … Cranial Bones - Parietal • Axis runs parallel to the sagittal suture through the change of bevel at the anterior & posterior borders of each parietal bone • In external rotation, the inferior borders of the parietal bone moves laterally. A “widening” occurs which is greatest at the posterior aspect of the bones. Internal rotation the inferior borders move medially. Parietal Motions of Flexion and Extension Flexion Extension • Midline Bones Flex • Paired bones externally rotate • Bi-parietal diameter increases • AP diameter decreases • Midline bones extend • Paired bones internally rotate • Bi-parietal diameter decreases • AP diameter increases Osteology A few key relationships Pterion These four bones overlap in alphabetical order from within outward • Frontal - anterosuperiorly • Parietal – posterosuperiorly • Sphenoid –lateral surface of great wing, anteroinferiorly • Temporal - centrally Frontal Sphenoid Parietal Temporal Netter Presenter: 2001. Pterion Strain Patterns Patterns of the SBS Strain Patterns • Flexion • Extension • Torsion – Right – Left • Side Bending Rotation – Right – Left • Lateral Strain – Right – Left • Vertical Strain – Superior Strain – Inferior Strain • Compression Physiologic Strain Patterns of SBS • Flexion • Extension • Torsion – Right – Left • Side Bending Rotation – Right – Left Flexion - Extension – Are the expected physiologic motions – Can be pathological if restricted in one extreme or another Flexion/extension Longer than usual cycle, typically (Similar to prolonged exhalation in COPD) Will have different feels at the ‘endpoints’ of the Extension phases Will have decreased flow in the opposite phase (e.g., flexion dysfunctions will have diminished extension pattern) Flexion FLEXION EXTENSION ER Flexion • • • • Findings-all quadrants in external rotation – Increased transverse diameter – Forehead wide and sloping(brow prominent with forehead receding) – AP diameter equal on both sides – Sagittal suture flattened or depressed Sphenoid – Superomedial-inferolateral diameter greater – Orbits wider – Eyeballs protuberant – Increased fronto-zygomatic angle – Frontal processes of maxillae are nearly in coronal plane – Maxillary palantine processes flattened Occiput – Protruding ears – Mastoid tips posteromedial Maxillae – Nasolabial crease deeper ER ER ER Extension • Findings-all quadrants in internal rotation – – – • Sphenoid – – – – – – • Superomedial-inferolateral diameter decreased Decreased frontozygomatic angle Orbit narrowed Eyeballs retruded Frontal processes of the maxillae are nearly in sagittal plane Maxillary palantine processes arched Occiput – – • Long narrow head Decreased transverse diameter Forehead prominent with Brow receding Ears close to head Mastoid tips anterolateral Maxillae – Nasolabial crease shallow IR IR IR IR TORSION One axis – Antero-superior to Infero-posterior – Spenoid and occiput rotate in opposite directions – Named for superior great wing of sphenoid Torsion • Torsion of the sphenoid about an anteroposterior (AP) axis extending from the nasion through the symphysis to opisthion • The sphenoid & anterior skull components are in one direction, the occiput & posterior components in the other. • This strain is named for the side of the high wing of the sphenoid, right torsion (RT) or left torsion (LT) Right Torsion • • Findings- asymmetric quadrants Sphenoid-1 quadrant in external rotation • Higher greater wing side relative to the other – – – – Orbit wide Frontolateral angle anterior Zygomatic orbital rim everted Maxillary frontal processes in more coronal plane – Maxillary palantine processes flattened • Occiput-1 quadrant in external rotation • Low occiput side relative to the other – Protruding ears – Mastoid tips posteromedial IR ER IR ER SIDEBENDING ROTATION Two axes: A-P and bilateral vertical axes – Occiput and Sphenoid rotate same direction on AP axis; side-bend away from each other on parallel vertical axes. Named for convexity Sidebending – Rotation Strain • Occurs around an AP axis & around 2 parallel vertical axes: one through the body of the sphenoid & one through the foramen magnum, perpendicular to the physiologic transverse axes & the A-P axis • As the SBS sidebends, it also rotates inferiorly to the convex sidebending side (coupled motion) • Named for the convex side of sidebending Lt Sidebending – Rotation Strain Right Sidebending Rotation • Findings- 1 side of face full and convex with the opposite side flattened (side of the lower greater wing of the sphenoid) • Sphenoid– Side of low greater wing in internal rotation • • • • • • Lateral fontal angle posterior Orbit narrower Eyeball retruded Frontozygomatic angle lessened Zygomatic tuberosity prominent Maxillary frontal process more sagittal • Maxillary palantine process more arched • Occiput • Mastoid tip –posteromedial • Ear protruding ER IR IR ER Non-physiologic Strain Patterns of SBS • Lateral Strain – Right – Left • Vertical Strains – Superior Strain – Inferior Strain • Compression LATERAL STRAIN • Bilateral vertical axes • Shearing force at SBS causing Sphenoid and Occiput to rotate same direction on axes • Named for position of basisphenoid • Head appears “parallelogram” Lateral Strain • Sphenoid and occiput have the same rotation about a vertical axis, resulting in a lateral strain pattern • Can happen with a one-sided impact from the front or back of head (off- center impact) • Named for the position of the base of the sphenoid, relative to the occiput at the SBS • Also known as “parallelogram head” Left lateral strain VERTICAL STRAINS • Sphenoid and Occiput rotate same direction on parallel horizontal axes • Named for position (superior/inferior) of base of Sphenoid Vertical Strain -Superior/Inferior • Sphenoid and occiput have the same rotation about a transverse axis, resulting in a vertical strain pattern • Named for the position of the base of the sphenoid, relative to the occiput at the SBS Superior Shear Inferior Shear Inferior Shear Superior Shear Superior Shear SBS Compression • Aka, ‘bowling ball head’ • This is where the SBS has been compressed (think of a ‘jammed’ finger), causing a near total lack of motion at the SBS in any particular direction • Most commonly seen in frontal impact trauma, difficult births, and circumferential loads to the skull, but can also be seen in severe psychiatric & emotional states SBS Patterns Axes A-P Transverse Vertical Paired Naming SB-Rot=Convexity Torsion=High Gr Wing Rest=Sphenoid Base Direction Overview of Motions • Occiput, sphenoid, ethmoid, vomer – Rotate about a transverse axis during physiologic Flexion and Extension • Paired bones of the periphery – Frontals, temporals, parietals, maxilla, palatines, zygomae – Rotate externally during cranial flexion – Rotate internally during cranial extension Observational Diagnosis • • • • Flexion Extension Torsion Sidebending Rotation • Observational diagnosis Observe face from the frontal and from superior view of the head Picture Effect on Internal/External Rotation on Paired Bones of Face Easiest: Flexion or Extension Type • Palate/Dental Arch: – Extension = high & narrow – Flexion = low & wide Face affected most by Sphenoid; Temporals & Sacrum by Occiput Diagnosis by Visual Observation • • • • • Flexion Extension Orbit widens/ protrudes Nasolabial crease deeper Flattened Cheek Ears – outflared Decreased Frontal Eminence • • • • • – Sloping forehead • Prominent Brow/Superciliary ridge Orbit narrows/ recedes Nasolabial crease shallow Cheek prominent Ears- inflared Increased Frontal Eminence – Vertical forehead • Receding Brow/Superciliary Ridge Vault Hold • Pt supine, you gently place your hands on the lateral aspects of the cranium with the following landmarks: – Index fingers in the temple (not temporal) region, over the greater wings of sphenoid – Middle finger just in front of the ear on the temporal bone – Ring finger just behind the ear on the temporal bone – Little finger as close to the mastoid portion of the occipitomastoid suture as possible – Thumbs gently resting on parietals or frontal bone, wherever they fall for your hands on the patient’s skull Flexion Extension Fronto-Occipital Hold • Patient supine, with head at 3/4 of table. • Physician at side of head of table. • One hand cupping occiput. • Other hand lightly palpating frontal bone • General sensation is that of: – Shortening of A/P axis with Flexion – Elongation of A/P axis with Extension Flexion = Shortening of A/P axis Extension = Lengthening of A/P axis Temporal Bone as “Trouble-Maker” External Rotation of Temporal = Pressure on Trigeminal Ganglion & Tightens Cave Cranial Nerves - Summary Temporal Bone as “Trouble-Maker” Olfactory Nerve - CNI Hx: Blow to head • Anosmia • Altered sense smell Physical: • Ability to smell • Frontal bone motion • Also sphenoid, ethmoid, vomer motion Tx of Dysfunction: Frontal lift – Ethmoid pump OMT CN III, IV, VI Group: Motor to Extra-Ocular Ms’s III: Parasympathetic (Accommodation) Petrosphenoidal Ligament and its association with CN III, IV, VI Attached border of Tentorium “Petrosphenoidal Ligament” (Ligamentous thickening from end of Petrous Temporal to Sphenoid) CN III over; CN IV through; CN VI under & at tip of the temporal External Rotation CNV - Trigeminal • Structure • Sensory to the Face • Motor to the muscles of mastication • V1=SOF, V2=Foramen rotundum, V3=Foramen ovale; Meckel’s cave, petrosphenoid ligaments, Cervical spine • Dysfunction • Anesthesia, Trigeminal neuralgia (“Tic douleroux”) • History • Physical examination • Trauma, Plagiocephaly • Test sensation, corneal reflex • Evaluate temporal (petrobasilar), sphenoid • Function CN VII - Facial Nerve • Function • Structure • Dysfunction • Motor to facial muscles Parasympathetic to glands Special sense to tongue • Stylomastoid foramen internal acoustic meatus • Paralysis, weakness, no or poor taste sense • Viral illness, trauma • History • Test facial expression, taste • Physical examination • External rotation of temporal and sphenoid bones CN VIII - Vestibulocochlear Nerve • Function • Sensory - hearing and balance • Structure • Dysfunction • Internal acoustic meatus • History • Physical examination • Hearing deficit, tinnitus, vertigo, otitis media and interna • Trauma, infectious diseases • Evaluation of temporals & sphenoid; balance; hearing CN IX - Glossopharyngeal Nerve • Function • Motor to muscle; Parasympathetic to glands; Sensory to palate • Structure • Jugular foramen • Dysfunction • History • Physical examination • Difficulties swallowing, excessive gag reflex • Trauma to occiput &/or temporals • Test gag reflex • Evaluation of temporals, occiput, occipitomastoid suture CN X - Vagus Nerve • Function • Structure • Dysfunction • History • Physical examination • Motor to striated muscle; Parasympathetic to smooth muscle and glands; Sensory from viscera • Jugular foramen, Foramen magnum • Numerous Somatovisceral; Posterior Headaches; More • Trauma occiput, temporal • Test gag reflex • Evaluate OA, AA, C2, temporal, occiput, OM suture CN XI - Accessory Nerve CN XI - Accessory Nerve • Function • Structure • Dysfunction • History • Physical exam • Motor • Cervicals, Foramen magnum, Jugular foramen • Weakness/paralysis, torticollis; Recurrent Trigger Points in SCM & Trapezius • Trauma to cervicals, occiput, temporals • Test SCM & Trapezius muscles; Evaluate cervicals, occiput, temporals CN XII - Hypoglossal Nerve • Function • Structure • Dysfunction • Motor to Tongue • Hypoglossal canal • Dysphagia, tongue function • History • Trauma to occiput (condyles) • Physical examination • Test tongue motions • Evaluate occiput (condyles), upper cervicals Questions?