The document summarizes key aspects of back kinesiology including: - The functions of the back include weight bearing, shock absorption, mobility, spinal cord protection, and limiting excessive motion. - Discs absorb compressive forces and allow for height changes throughout the day. Disc height decreases with age as water content reduces. - Cervical and lumbar spine ranges of motion are described. Muscles including erector spinae, splenius, and transversospinalis work to support the spine. - Scoliosis can be postural or structural, often involving rotation that deforms spinal elements over time if left uncorrected.

1. Kinesiology of the back

2. Functions
• Weight bearing
• Shock absorption
• Mobility
• Spinal cord protection
• Limitation of excessive motion
• Muscle attachments

3. Anatomy - bones

9. IV discs
Loading commonly occurs eccentrically
Compressive forces squeeze water out – water regained in non weight bearing postures
2cm taller when you wake up than when you go to sleep
Over 30 years – less water, more fibres, less elastic fibres
Older ages – loss of disc height

15. Disc prolapse

16. Cervical ligaments

17. Ligaments

18. Spinal ligaments are usually in a state of stretch and are responsible for the residual
compressive force in vitro after removal of all mucles

19. Muscles

20. Splenius

21. Erector spinae

22. Tranversospinalis

23. • Work in concert with spine flexors eg. the
longitudinal and oblique abdominals (Lumbar)
• Longus coli, capitis and scalene muscles (neck)

24. Osteokinematics - Cervical
• Extension/flexion at C2 to C7 – 8 -170
• Lateral flexion 7 – 100
• Rotation 9 -120
– 50% of flexion extension happens in the upper cervical
– 50% of rotation happens in C1-2 level
– Lateral flexion mostly on the middle part of the cervical
spine
• Loading through supporting the head ≈ 4kg
• Centre of gravity of head passes anterior to AO joint
• Strong posterior neck muscles resist head weight

25. Instantaneous axis of rotation

27. Osteokinematics - lumbar
• Rotation nil
• Extension T12/L1 – 120 L5/S1 – 200
• Lateral flexion T12/L1 – 60 L5/S1 – 30

28. • Forward flexion – executed by eccentric
contraction of erector spinae and the hamstrings
• Beyond 810, the critical point, erector spinae is
deactivated
• Beyond this level, contraction of erector spinae
leads to compressive loading as opposed to
extension
• Passive joint structures (ligaments) limit further
flexion.

29. • What effect does bringing the weight closer to the body have?
• Reduces the value of the lever arm, reduces the amount of work that the
postvertebral (erector spinae muscles need to do.
• Reduces compressive loading across the intervertebral discs

31. Scoliosis

32. Scoliosis imaging

33. Scoliosis
• Classified as postural or structural
• Almost always involves a rotational
component

34. • Rotation causes typical deformations of the
spinal elements
• Typically anterior portions of the vertebrae
grow faster than the posterior elements →
primary lordosis

35. • Vertebrae rotate to
create space for
continued growth
• Spine flexion is always
accompanied by
rotation

36. • Altered spinal shape affects muscle function
and will worsen the spinal bend, cause pain
and in severe cases affect respiratory
expansion of the thoracic cage
• Adolescent scoliosis will affect the developing
spine and lead to deformation of growing
vertebrae

37. Attempts at correction
Utilise creep

38. Bracing

39. • And of course surgery a
last resort or in severe
and progressing cases