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James W. DeVocht, DC, PhD

Module 2 Functional Anatomy of the Lumbar and Thoracic Spine (Herzog Chapter 2 - McGill) Biomechanics (TECH 71613). James W. DeVocht, DC, PhD. Typical Lumbar Vertebra. Herzog Fig 2-1. Trabeculae Alignment. Herzog Fig 2-2. Damage in trabeculae. Herzog Fig 2-3.

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James W. DeVocht, DC, PhD

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  1. Module 2Functional Anatomy of the Lumbar and Thoracic Spine(Herzog Chapter 2 - McGill)Biomechanics (TECH 71613) James W. DeVocht, DC, PhD

  2. Typical Lumbar Vertebra Herzog Fig 2-1

  3. Trabeculae Alignment Herzog Fig 2-2

  4. Damage in trabeculae Herzog Fig 2-3

  5. Stellate Fracture of Endplate Herzog Fig 2-4A

  6. Intrusion of nuclear material into vertebral body Herzog Fig 2-4B

  7. Schmorl’s Node

  8. Z Joint Binding: folds of the capsular ligament can get caught between the articular surfaces Herzog Fig 2-5

  9. Failure of posterior bony elements & avulsion of end plate from the rest of the vertebral body – often caused by A-P shear forces Herzog Fig 2-6

  10. Fatigue Failure(not common in posterior elements) endurance limit Nordin Fig 1-12 Asymptote: a straight line that is approached but never met by a curved line (asymptotic relationship)

  11. Fatigue(in human cortical bone specimens) Nordin Fig 2-38

  12. Elastic and Plastic Deformation Strain Nordin Fig 2-8

  13. Brittle vs. Ductile Stress (s) Strain (e)

  14. Strain Rate Dependency(viscoelasticity) Stress (s) Strain (e) Nordin Fig 1-9 silly putty (2:02) http://video.google.com/videoplay?docid=-5087324355648452072&q=silly+putty&total=584&start=0&num=100&so=0&type=search&plindex=0

  15. Set up for Creep and Recovery Test from Nordin Fig 1-10

  16. Creep and Recovery Test Experimental setup (constant load applied for a time and then released) Stress (s) t, time Response of 3 different types of materials (degree of strain over time) Strain (e) t, time Strain (e) t, time Strain (e) t, time from Nordin Fig 1-10

  17. Stress-Relaxation Test Experimental setup (stretched a set amount and then held in place) Strain (e) t, time Response of 3 different types of materials (degree of stress over time) Stress (s) t, time Stress (s) t, time Stress (s) t, time from Nordin Fig 1-11

  18. Viscoelastic Materials - Have properties of both a liquid and a solid (but each material is either a liquid or a solid) - Take some time to respond to forces - Loss of strain energy as heat - Most are stiffer with higher strain rates

  19. Intervertebral Disc Kapandji Fig 25 Herzog p 28-9

  20. Annulus Layers Kapandji Fig 26 Herzog p 29

  21. Compressed IVD Compressed (tends to cause delamination in older people) Normal Herzog Fig 2-7 (Descriptions are reversed in the book & says “thickened” when compressed)

  22. Conclusions about bulging or herniated IVDs from large compressive loads 1. Disc is typically younger & bent to end of ROM (older discs tend to delaminate & crack) 2. Takes repeated loading (~25,000 times) 3. Commonly associated with prolonged sitting Herzog p 29-30

  23. Physical characteristics of muscles relate to their function 1. Size 2. Orientation 3. Fiber architecture a. Type I – fatigue resistant b. Type IIA c. Type IIB – high force, short time Herzog p 30-2 Nordin p 165-6

  24. Muscle Levels – Transverse Scans(can be misleading regarding belly size) Herzog Fig 2-8

  25. Short Muscles of the Spine(movers or stabilizers?) Herzog Fig 2-9

  26. Major Extensors of the Lumbar Spine:longissimus, iliocostalis, & multifidus groups Herzog p 33 Intermediate Layer Deep Layer Snell Fig 8-16 Snell Fig 8-17

  27. Bundles of Longissimus Thoracis Pars Thoracis(tendon runs superficial to lumbar musculature) Herzog Fig 2-10

  28. Significance of the Line of Force on Moment(tendon runs superficial or deep) Herzog p 33

  29. Path of Deep Lumbar Muscles Herzog Fig 2-11

  30. Lines of Force of Oblique Muscles external oblique linea semilunaris (lateral edge of rectus abdominus) transverse abdominis internal oblique Herzog Fig 2-12

  31. Partitioned Muscle Belly(rectus abdominus is primary flexor of trunk) Herzog p 35 http://www.youtube.com/watch?v=KyljiZ6rcl8&feature=related

  32. General Tendencies Muscles that are movers: - attach in few places - active only during specific movements Muscles that are stabilizers: - attach in many places - active during many movements

  33. Psoas: hip flexorQuadratus Lumborum: stabilizer of lumbar spine Herzog p 35-6

  34. Major Lumbar Ligaments ALL: Anterior Longitudinal Ligament PLL: Posterior Longitudinal Ligament LF: Ligamentum Flavum ISF: Inter-Spinous Ligament SSL: Supra-Spinous Ligament Herzog Fig 2-13

  35. Interspinous ligament runs obliquely to compressive axis Herzog Fig 2-14

  36. Paratenon is a sheath isolates tendons Nordin page 108

  37. Four zones of increasing stiffness of tendons as they near the attachment to bone (strain relief) Nordin page 108

  38. Source of pain and sensation in muscles & ligaments is a complex issue • There are several different types of receptors (pain, temperature, pressure, and other “touching” sensations) • Pain can originate at higher levels in the pain pathway (pressure on dorsal root or other ganglion) Herzog page 40-1

  39. Different types of pain sensation can be caused by probing different areas - burning - scraping - electric - mechanical pressure - a general “sick feeling”- boring Herzog page 41

  40. Fall on coccyx can lead to pressure on ganglion impar

  41. Spinal nerve interference can result in sensation of pain along dermatomal levels Irritation of an afferent nerve somewhere along its path (like at the IVF) can induce action potentials that the brain interprets as pain at the end of the nerve, where the receptor is. Gray’s Anatomy, 36th Ed, Fig 7.233A

  42. Range of Motion of Each Spine Level in DegreesLevel Flex/Ext Lat Bend Axial T1-2 4 6 9 T2-3 4 6 8 T3-4 4 6 8 T4-5 4 6 8 T5-6 4 6 8 T6-7 5 6 8 T7-8 6 6 8 T8-9 6 6 7 T9-10 6 6 4 T10-11 9 7 2 T11-12 12 9 2 T12-L1 12 8 2 L1-L2 13 6 2 L2-L3 13 6 2 L3-L4 13 8 2 L4-L5 15 6 2 L5-S1 14 3 5 adapted from Herzog Table 2-5 on p 42

  43. There are large variations in range of motion and stiffness among different individuals and between segments of a single person Asymmetry, or unusual values suggests the possibility of pathology (could be normal variation) Herzog page 41

  44. Range of Motion Can be Large gymnist (2:58) http://video.google.com/videoplay?docid=841651212169523424

  45. Center of Rotation Every movement of a rigid body in a plane from one position to another can be accomplished by rotation about some point in that plane. That point is known as the center of rotation for that particular movement. from White & Panjabi page 20

  46. Finding the Center of Rotation 1. Pick two points that are not close together, but are distinct on both views 2. Draw straight lines connecting the same points on each of the two views 3. Draw perpendicular bisectors of each line 4. They intersect at the center of rotation Nordin Fig 11-18 Two radiographs are overlaid so that the C5 vertebra of one is superimposed on C5 vertebra of the other.

  47. The Path of the Instantaneous Center of Rotation Can be Diagnostic Nordin Fig 10-8

  48. Stiffness by Motion Palpation

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