1. Chapter 9 The spine: Objectives
Explain how anatomical structure affects movement capabilities of the spine
Identify factors influencing relative mobility and stability of different regions of the spine
Explain the ways in which spine is adapted to carry out its biomechanical functions
Explain the relationship between muscle location and the nature and effectiveness of muscle action in the trunk
Describe the biomechanical contributions to common injuries of the spine

2. The Spine: Outline Structure Muscles and movements Low Back Pain
Strengthening exercises
Lifting guidelines
Common low pack problems
WebSite for spine and spinal problems:
Spinal problems website
Study questions for exam (do not submit, just do on your own):
Introductory problems, p 305: 1,6,7,9,10
Additional problems, p 306: 1,5,8

3. Structure of the Spine

4. Structure of Vertebrae
Note: orientation of facets largely
determines amount of movement possible
Facets and discs share load bearing
Question #5, p 306

5. Facet Orientation – related
To movement capability

6. Segmental Movements
Question #1,
P 305

7. The Spine: Muscles Spinal flexors – abdominal muscles Spinal extensors
Rectus abdominis
External and internal obliques
Spinal extensors
Splenius cervicis and capitis (cervical)
Erector spinae (lumbar and thoracic)
Quadratus lumborum (lumbar)

8. Muscle force vectors

9. Flexion Exercises Effect of Anchoring feet? Bending knees?
Placement of hands and arms?
Inclined board?

10. Back Extension Exercises to Avoid:
Good morning exercise:
Hyperextended back:

11. Recommended Extension Exercise

12. Loads on the spine:
Line of gravity for upper body passes anterior to vertebral column, creating a forward torque
It is important to keep pelvic
girdle balanced! (Question
# 6, 7 p 305)

13. Effect of posture on lumbar compression force:

14. Torque while lifting

15. Lifting recommendations
(1)bend knees , (2) keep weight close to hips

16. Lifting recommendations
(3) Avoid lifting while twisting and asymmetrical frontal plane loading of the trunk– it places 3 times more stress on the spine (question #9, p 205) (4) Avoid rapid, jerking motion while lifting
Lifting recommendations

17. Common Spinal Injuries
Lumbar spinal injury is by far the most prevalent of all areas of the spine
Low back pain is most common and most expensive injury in work place
Low back pain is
usually related to
mechanical stress
60% of cases are
ideopathic

18. Stress Fractures
Most common type of vertebral fracture is in pars interarticularis
Spondylolysis
Spondylolisthesis
Spondylolysis and spondylolisthesis don’t tend to heal with time
Common with sports involving repeated hyperextension of the lumbar spine.

19. Common low back problems
Spondylolisis – separation of vertebra
Spondylolisthesis – forward movement of
vertebral body
Disc degeneration

20. Disc Herniations Cause of 1-5% back pain cases
Protrusion of part of nucleus pulposus from the annulus.
Traumatic or stress related.
Common sites: between 5th-6th and 6th-7th cervical vertebrae and 4th-5th lumbar and 5th lumbar and 1st sacral.
Sensory nerves supplying anterior and posterior longitudinal ligaments generate pain signals.

21. Two common causes of low back pain
Spinal problems website
Compressive, or neurogenic:
Symptoms are referred due to
Spinal nerve compression
Mechanical - localized pain due to
Damage to facets, discs, and/or soft
tissue