1. Kinesiology
The Spine

2. Spinal Column Structure
Base of support.
Link between upper and lower extremities.
Protects spinal cord.
Stability vs. mobility
Example: cervical vs. thoracic spine

3. 5 Regions of Vertebral Column
Cervical
Thoracic
Lumbar
Sacral
Cocygeal
33 bones and 23 disks

4. Curvatures Viewed Laterally
Prior to birth “C-shaped”.
4 distinct curves in an adult.

5. Cervical Lordosis
Thoracic Kyphosis
Lumbar Lordosis

6. Spinal Motion Spinal movement is the combination of:
Intervertebral joints
Facet joints

7. Intervertebral Joints

8. Intervertebral Disc
Intervertebral disk make up 20-30% of the height of the column and thickness varies from 3mm in cervical region, 5mm in thoracic region to 9 mm in the lumbar region.
Ratio between the vertebral body height and the disk height will dictate the mobility between the vertebra –
Highest ratio in cervical region allows for motion
Lowest ratio in thoracic region limits motion

9. Disc Structure
Nucleus Pulposus (NP) is located in the center except in lumbar lies slightly posterior.
Gelatinous mass rich in water binding PG (proteoglycan) AKA (glycoaminoglycos) GAG-protein molecule.
Chondrotin-4 sulfate in PG molecule gives the disc a fluid maintaining capacity (hydrophyllic) - decreases with age.
Hydration of the disc will also decrease with compressive loading - this loss of hydration decreases its mechanical function.

10. Disc Structure 80-90% is H2O – decreases with age.
Disc volume will reduce 20% daily (reversible) which causes a loss of mm of height in the spinal column.
Acts as a hydrostatic unit allowing for uniform distribution of pressure throughout the disc.

11. Disc Structure
Compressive stresses on the disc translate into tensile stresses in the annulus fibrosis
This makes the disc stiffer which adds stability and support to the spine.
Bears weight and guides motion.
Avascular - nutrition diffusion through end-plate.

12. Annulus Fibrosis
Collagen arranged in sheets called lamellae (outer layers).
These lamellae are arranged in concentric rings layers that lessen in number with age and thicken (fibrose).
Enclose the nucleus and oriented in opposite directions at an angle of 120 degrees (or degrees).
Controls the tensile loading from shear, accessory motions in the anterior compartment and disc forces which can be up to 5x the external compression force.

13. Annulus Fibrosis
Mostly avascular and lacking innervation but the outermost layers are probably innervated (sinovertebral nerve).
Thickest anteriorly.
Outermost 1/3 connects to vertebral body via Sharpie’s fibers.
Outer 2/3 connect to the end plate.

14. Disc Pathology - Herniation
Highest incidence at C5-6, C6-7, L4-5, and
L5-S1.
Disc herniation
Disc protrusion or bulge - contained
Annulus intact.
Localized – usually lateral
Diffuse – usually posterior
Prolapsed – not contained
Annular fibers disrupted – inner layers
Extrusion - migration through all layers

16. Longitudinal Ligaments
Anterior longitudinal
Supraspinous
Posterior longitudinal
Ligamentum flavum (elastic)
PLL diverts herniation posteriolaterally

17. Posterior Structures (Elements) of Motion Segment
Pedicles and lamina form the neural arch.
Facet joints between the superior and inferior articulating surfaces.
Transverse and spinous processes.
Interspinous and supraspinous ligaments.
Ligamentum lavum.
Intervertebral foramina.

18. Facet Joint
Articulation between the superior (concave) and inferior (convex) facets.
Guide intervertebral motion through their orientation in the transverse and frontal planes.

19. Facet Joint Capsule Limit motions.
Strongest in thoracolumbar and cervicothoracic regions where the curvatures change.
Resist flexion and undertake tensile loading in the superior portion with axial loading or extension.
Resists rotation in lumbar region.

20. Intervebral Foramina Exit for nerve root.
The size is dictated by the disc heights and the pedicle shape.
Will lose space with osteophytic formation, hypertrophy of ligaments and loss of disc height with aging – lateral stenosis.
Decreases by 20% with extension and increases 24% with flexion

21. Spinal Stability
The column’s ability to react to multiple forces placed on it.
Degeneration increases instability.
Body reacts to restore through fibrosus and osteophytic changes.

22. Types of Segmental Loading
Axial Compression
Bending
Torsion
Shear

23. Axial Compression
Caused by gravity, ground reaction forces, muscle contraction and ligaments reaction to tensile forces.
Intradiscal loads can range from 294N to 3332N depending upon position.
Most load in anterior segment, posterior can load from 0-30% depending upon segments position.
Compression at the disk causes tension at the annulus, changing the angle of the fibers and increasing the stability.

24. Axial Compression (cont’d)
Creep will occur in the disc, will be larger with increased force and aging.
5-11% of H2O is lost through creep.
Creep is rapid 1.5-2mm in 10 min.
Plateaus at 90 minutes.

25. Bending
Combination of compression, shear and tensile forces on the segment from translation.
Bending into flexion will be resisted by posterior annulus, PLL and the facet capsule and anterior compressive forces on the anterior structures causing disc displacement.
For extension posterior compressive forces in anterior segment and there is a tensile load in facet capsule and ALL.

26. Torsion Caused by axial rotation and coupled motions.
Stiffness may increase due to facet compression with certain motions i.e., flexion increases torsional stiffness at L3-4.
Annulus fibrosus resists, 1/2 fibers CW other 1/2 CCW facets may help depending upon the orientation (resists in a tensile manner).
When combined with flexion the amount of force required for tissue failure is decreased.

27. Shear Facet joint resists especially in the lumbar area.
Annulus will undergo some tensile forces depending upon direction and the fiber orientation or angle.
Discs also resist but if creep occurs - the facet may undergo more loading.

28. Mobility Amount and direct of motion in a segment is determined by:
Vertebral body/disc size.
Facet orientation frontal vs. sagittal.

29. Flexion
Superior vertebra will anterior tilt and forward gliding will occur:
Widening the intervertebral foramina 24%.
Adds compressive forces on the anterior aspect of the anterior segment moving the nucleus pulposus posteriorly.
Tensile forces placed on posterior annulus, flavum, capsule and PLL.
Central canal is widened
Rationale for some of William’s flexion exercises

30. Extension
Superior vertebra will tilt and glide posteriorly and the intervertebral foramina narrowed up to 20%.
The central canal is also narrowed.
Nucleus pulposus moves anteriorly

31. Lateral Flexion
Superior vertebra will translate, tilt and rotate over inferior - direction will differ.
Concavity towards, convexity opposite
Tensile forces on convexity, compressive forces on concavity
Extension in ipsilateral facet.
Flexion in contralateral facet.

32. Rotation
Accessory motions are like lateral flexion due to same coupling in cervical and upper thoracic spine.
Exception with lower T/S and L/S in neutral coupling then opposite (in most references).
If the motion segment is flexed or extended spine (in most references) the coupling will be the same.

33. Regional Structural and Functional Differences
Differences are apparent due to connection requirements, sacral, upper C-spine, all junctions
Vertebral body size increases with support requirements.
Cervical, thoracic,lumbar, and sacral/cocygeal.

34. Cervical CO - occipital C1 - Atlas C2 - Axis
C3-6 - general basic structure

35. Cervical Region Function
Mobility > Stability.
Upper cervical unit – C0-2
Lower Cervical unit
C2-7

36. C0-1 C0 – occiput – containing the occipital condyle – convex.
C1 - no body, disk and spinous process allows for free space and a large neutral zone and cord protection - this means more motion.
Lateral facets of CO on C1 - concave C1 on convex CO - flex/ext or nodding and minimal to no lateral flexion/rotation.

37. C1-2 2 facets laterally and 1 medially with dens and anterior arch
transverse ligament helps control (C1 on C2 anterior displacement), stabilizes – allows nodding
also provides cartilaginous surface as does the alar ligament - limits flex/ext so right rotation requires left lateral facet to slide anterior and right lateral facet to slide posterior – so rotation is coupled with extension.
Can account for up to 50% of rotation in the neck and most of the initial ROM.

38. C2-7 50% wider than they are deep.
Transverse process holds foramen for vertebral artery, vein and plexus, and grove for the spinal nerve.
Facet orientation is roughly 45 degrees(35-65) in the transverse plane w/ loose capsule - allows for motion in all planes and more rotation and lateral flexion than other regions.

39. Thoracic Spine Function
Articulation for the ribs
Least mobility
Increasing load bearing
Lat flex flex/Ext

40. Thoracic Spine Body T1 - similar to cervical in (C7a).
Normally the vertebral body equals width and depth.
The ratio of disc diameter to height is highest. This will:
Decrease tensile forces
Decrease possibility of disc injury
Posterior aspect becomes thicker as you go lower - ribs bigger (articulates) and more compressive forces.
End-plates become larger (higher compressive forces) as you go caudally.

41. Thoracic Spine
Less flexible due to rib articulation, smaller disc to body ratio, spinous process.
Flavum and ALL are thicker; facet capsule less flexible.
Upper thoracic spine facet orientation
Limits flexion extension - 60/20 transv/front
Allows coupled lat/rot. (rot of spinous process to the convex side)
Facets are more sagittal in T9-12 to allow flex/ext and rot of spinous process will be toward concavity (lumbar coupling).

42. Thoracic Spine
Rib articulation consists of 2 articulations to the thoracic vertebra –
Anterior surface of the lateral process
Lateral aspect of the vertebral body.
Bucket handle motion of the ribs with breathing.
Extension and contralateral lateral flexion ribs separate.
Flexion and lateral flexion ipsilaterally compresses ribs.

43. Thoracic Spine Scoliosis will cause a rib hump.
Combination of tranverse plane rotation and frontal plane sidebend – contralateral coupling.
Convex side will occur on the ipsilateral rotated side – causing hump.

44. Lumbar Spine Most load bearing structures in the skeletal system
Sagittal plane motion
Largest body/disc, lamina and pedicles short and thick for load bearing.

45. Lumbar Spine
L5 transitional, wedge shape of body and disc – Anterior > posterior.
L5-S1 most flexion extension.
Coupling of motion - right lateral flexion will result in right sidebend and left rotation of vertebral body (when L/S in neutral)

46. Spinal Musculature Mobility vs. Stability
Slow twitch SO vs. fast twitch FOG
Energy storage
Consider the line-of-pull of all spinal muscles

47. Spinal
Muscles

48. Common Theme Small angle of insertion Therefore: Rotary component
Compressive component

49. Common Theme Small angle of insertion Therefore: Rotary component
Compressive component
When are active vs. passive exercised indicated? When are they not?

50. Hip Flexors &
Abdominals

51. General Comment Regarding Function
Contracture vs. contraction

52. General Comment Regarding Function
Contracture of hip flexors and effect on lumbar spine

53. General Comment Regarding Function
Abdominals
Pelvic stability/balance
Guy-support system