Chapter 9 The spine Objectives Explain how anatomical

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

The Spine: Outline • • Structure Muscles and movements Low Back Pain Strengthening exercises Lifting guidelines Common low pack problems Website for spinal problems (Click on “view eorthopod”, then “spine-lumbar”, then “low back pain”) • Study questions (do not submit, just do on your own): – Introductory problems, p 305: 1, 6, 7, 9, 10 – Additional problems, p 306: 1, 5, 8

Structure of the Spine

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

Facet Orientation – related To movement capability

Segmental Movements Question #1, P 305

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)

Muscle force vectors

Flexion Exercises • Effect of – Anchoring feet? – Bending knees? – Placement of hands and arms? – Inclined board?

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

Recommended Extension Exercise

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)

Effect of posture on lumbar compression force:

Torque while lifting

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

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

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 • Website on low • back pain

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

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.

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

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 1 st sacral. • Sensory nerves supplying anterior and posterior longitudinal ligaments generate pain signals.