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 spine and spinal problems: MMG - Patient Education back TOC Introductory problems, p 305: 1,6,7,9,10 Additional problems, p 306: 1,2,3,5,8

Structure of the Spine

Structure of Vertebrae Note: orientation of facets largely determines amount of movement possible Facets and discs share load bearing Question #9, p 305

Facet Orientation – related To movement capability

Segmental Movements Question #1, P 305

The Spine: Muscles Abdominal muscles (flexors) Spinal extensors 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 319)

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 (4) Avoid rapid, jerking motion while lifting Lifting recommendations

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 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.

Whiplash Injuries Relatively common injury to cervical region. Usually from automobile collisions, where neck undergoes sudden acceleration and deceleration. Symptoms: Neck pain, muscle pain, pain or numbness radiating from neck to shoulders, arms, hands and a headache (present in 50-60% of most cases)

Low Back Pain 75-80% of population will experience it at some time in their life Mechanical stress plays a significant role Children Relative Stability of Spine 60% of cases is idiopathic (unknown origin) Abdominal exercises help in treatment

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