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: MMG - Patient Education back TOC Study questions for exam: –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 –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. (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 Disc degeneration Spondylolisis – separation of vertebra Spondylolisthesis – forward movement of vertebral body

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 5 th -6 th and 6 th -7 th cervical vertebrae and 4 th -5 th lumbar and 5 th lumbar and 1 st sacral. Sensory nerves supplying anterior and posterior longitudinal ligaments generate pain signals.

21. Two common causes of low back pain Compressive, or neurogenic: Symptoms are referred due to Spinal nerve compression Mechanical - localized pain due to Damage to facets, discs, and/or soft tissue Illustrations below are from: MMG - Patient Education back TOC MMG - Patient Education back TOC