1. The Trunk/Spine largest segment of body
most significant functional unit for general movement
integral role in upper and lower extremity function
relatively little movement between 2 vertebrae
Spine

2. The Vertebral Column 7 cervical vertebrae
develop as an infant begins to lift its head
Cervicothoracic junction
12 thoracic vertebrae
present at birth
Thoracolumbar junction
5 lumbar vertebrae
develop in response to weight bearing
Lumbosacral junction
Sacrum - 5 fused vertebrae
Coccyx fused vertebrae

3. Vertebral Articulation
Superior articular process
each articulation is a fully encapsulated synovial joint
these are often called apophyseal joints
Inferior articular process
Note: the processes are bony outcroppings.
Spine

4. Costal (Rib) Articulation
Inferior
costal
facet
Transverse
Superior
Note: the facets are the articular surfaces.
Spine

5. Body
Transverse process
Vertebral foraman
Spinous process
Intervertebral foraman

6. Muscular Attachments
muscular attachments on spinous and transverse processes
Spine

7. Vertebral shape changes to reflect movements possible within a given region
Spine

8. Further depiction
of vertebral shapes
Spine

9. Motion Segment: Functional unit of the vertebral column
Neural arches
intervertebral joints
transverse & spinous processes
ligaments
Two bodies of vertebrae
common vertebral disc
ant & post longitudinal ligaments

10. Intervertebral Disks ‘shock absorbers’ of the spine
capable of withstanding compressive
torsional and bending loads
role is to bear and distribute loads in
vertebral column and restrain
excessive motion in vertebral segment

11. Shock Absorbers
Bending Loads

12. 2 regions of vertebral disk
NP -- nucleus pulposus
gel-like mass in center of disk under
pressure such that it preloads disk
80-90% water, 15-20% collagen
AF -- annulus fibrosus
fibrocartilaginous material
50-60% collagen
Disc is avascular & aneural
so healing of a damaged disc is
unpredictable & not promising
Disc rarely fails under compression
vertebral body will usually fracture
before damage to disc occurs

13. Anterior Motion Segment
Ant. Longitudinal ligament
very dense & powerful
attaches to ant disc & vert body
limits hyperextension and fwd mvmt
of vertebrae relative to each other
Post. Longitudinal Ligament
travels inside the spinal canal
connects to rim of vertebral bodies &
center of disc
posterolateral aspect of segment not
covered - this is a common site for
disc protrusion
offers resistance to flexion

14. Posterior Motion Segment
Bone tissue in the pedicles and laminae
is very hard providing good protection
for spinal cord
Muscle attachments at spinous &
transverse processes
articulation between vertebrae occurs
at superior and inferior facets
these facets are oriented at different
angles related to spinal section
accounting for functional differences

15. Posterior Motion Segment
Ligamentum flavum spans laminae
connecting adjacent vertebral arches
very elastic thus aids in extension
following flexion of the trunk
under constant tension to maintain
tension on disc
Supraspinous and interspinous
ligaments span spinous processes
resist shear and forward bending
of spine

16. Spinal Movement collectively -- LARGE ROM flex/ext L-R rotation
L-R lateral flexion

17. ACCOMPANIED BY PELVIC TILTING
MOVEMENTS OF THE SPINE
ACCOMPANIED BY PELVIC TILTING
1st 50-60º in
lumbar vertebrae
Flexion beyond 50º
due to anterior
pelvic tilting

18. Regional ROM in Spine
Atlas (C1) & axis (C2) account for 50% of rotation in the cervical region.
Thoracic region is restricted, mainly due
to connection to ribs.

19. Spine - Posterior Muscular Support primarily produce extension and medial/lateral flexion
Superficial to deep
erector spinae
semispinalis
deep posterior
Spine

20. Spine - Posterior Muscular Support primarily produce extension and medial/lateral flexion
Posteriorly
erector spinae
iliocostalis
longissumus thoracis
spinalis
Spine

21. Erector spinae spinalis longissimus
Versatile muscles that can generate rapid force yet are fatigue resistant
iliocostalis
cervicis
thoracis
lumborum

22. Semispinalis
capitis
cervicis
thoracis

23. Deep posterior IT IS intertransversarius interspinales multifidus
rotatores

24. Abdominals rectus abdominis transverse abdominus external oblique
internal oblique

25. Intra-Abdominal Pressure
acts like a “balloon” to expand
the spine thus reducing compressive
load, this in turn reduces the activity
in the erector spinae
Internal & external oblique
muscles & transverse abdominis
attached to the thoracolumbar
fascia covering the posterior
region of the trunk
when these abdominals contract - added
support for the low back is created

26. Additional muscles contributing to trunk flexion
Collectively known as the iliopsoas
Powerful flexor
whose action is
mediated by the
abdominals
Quadratus lumborum
forms lateral wall of abdomen
also maintains pelvic position
during swing phase of gait

27. Movement into fully flexed position
1) initiated by abdominals (1/3 of flexor moment) and iliopsoas
2) once it has begun gravity becomes a contributing factor
such that the erector spinae act eccentrically to control
the movement (thru ~50-60º)
3) beyond 50-60º flexion continues by anterior tilt of pelvis
this mvmt is controlled by an eccentric action of hamstrings and gluteus
maximus while erector spinae contribution diminishes to zero
4) in this fully flexed position the posterior spinal ligaments and the passive
resistance in the erector spinae resist further flexion
5) this places the ligaments at or near the failure strength placing a greater
importance on the load sustained by the thoracolumbar fascia loads
supported thru the lumbar articulations
6) return to standing posture initiated by posterior hip muscles
7) erector spinae (1/2 of extensor moment) muscle active initially but peak
activity during the final 45-50º of movement

28. Strength of Trunk Movements
Extension
Flexion (70% of extension)
Lateral Flexion (69% of extension)
Rotation (43% of extension)

29. Postural Alignment 2 naturally occurring curves
LORDOTIC (in lumbar region)
KYPHOTIC (in upper thoracic lower cervical regions)
Abnormalities -- accentuated vertebral curves

30. Lumbar Lordosis exaggeration of the lumbar curve
associated w/weakened abdominals (relative to extensors)
characterized by low back pain
prevalent in gymnasts, figure skaters, swimmers (flyers)
Spine

31. Thoracic Kyphosis exaggerated thoracic curve
occurs more frequently than lordosis
mechanism -- vertebra becomes wedge shaped
causes a person to “hunch over”

32. Kyphosis aka “Swimmer’s Back”
develops in children swimmers who train with an excessive amount of butterfly
also seen in elderly women suffering from osteoporosis

33. Scoliosis lateral deviation of the spinal column
can be a ‘C’ or ‘S’ shape
involves the thoracic and/or lumbar regions
associated w/disease, leg length abnormalities, muscular imbalances

34. Scoliosis more prevalent in females cases range from mild to severe
small deviations may result from repeated unilateral loading (e.g. carrying books on one shoulder)

35. Consequences of Pelvic TiltTW Tm
in normal standing the line of gravity passes ventral (anterior) to the center of the 4th lumbar vertebral body
This creates a forward bending torque which must be counter-balanced by ligaments and muscles in the back
any movement or displacement of this line of gravity affects the magnitude of the bending moment (or torque)
slouched posture support comes from ligaments – this is bad for extended periods of time
Spine

36. Pelvic Tilt and Lumbar Loading
relaxed standing: the angle of inclination of the sacrum (sacral angle) is 30 to the transverse plane

37. Pelvic Tilt and Lumbar Loading
posterior pelvic tilt reduces the sacral angle or flattens the lumbar spine (reduces lordosis)
causes the thoracic spine to extend which adjusts line of gravity such that muscle expenditure is minimized
BUT load is now passed on to ligaments

38. Pelvic Tilt and Lumbar Loading
anterior pelvic tilt increases sacral angle
accentuate lumbar lordosis and thoracic kyphosis
this adjusts line of gravity to increase muscle energy expenditure

39. Pelvic Tilt and Sitting
Sitting (relative to standing)
pelvis posteriorly tilted
lumbar curvature is flattened
line of gravity (already ventral to lumbar spine) shifts further ventrally
increases the moment created by body weight about the lumbar spine
increased muscular support increases the load on the spine
vs.
Spine

40. Pelvic Tilt and Sitting
erect sitting
pelvis tilts anteriorly
increases lumbar curvature
reduces the moment arm of body weight
reduces need for muscular support
reduces load on lumbar spine
however, pelvis still much more tilted than during normal erect standing
vs.
Spine

41. L3 Load lowest when lying supine normal when standing upright
140% when sitting with no back support
150% when hunched over
180% when sitting hunched over with no back support
Spine

42. apparent that lumbar load is strongly related to support needed to maintain lumbar lordosis
in erect, supported sitting the addition of a back rest reduces lumbar load
reclining seated position reduces disc pressure even further

43. Spinal Injuries

44. Progression of Disc Degeneration

45. Degenerative Disks lose ability to retain disk integrity
decreases with
age
lose ability to retain
water in disk so
disks “dry out”
ability to distribute
load across disk
changes

47. Herniated Disks NP protrudes out from between the vertebrae
nerves are impinged by the bulging NP
lead to numbness and/or pain

48. Tearing of Annulus
Disk Herniation

52. Whiplash Rapid flexion/extension injuries in cervical region
strain posterior ligaments
dislocate posterior apophyseal joints
7th cervical vertebra is likely site for fracture in this injury

53. Low Back Pain Vertebral instability 1) Muscle strain from
lifting may create muscle
spasms
2) distorted posture for long
periods of time
3) avoid crossing legs at the
knee
4) tight hamstrings or
inflexible iliotibial band
5) weak abdominals
Vertebral instability

54. Lift With Your Legs What does this mean?
the idea is to keep the weight (W) as close to the axis of rotation as possible W
axis
muscular
torque
smaller
Spine