1 / 30

PHED 386

PHED 386. Biomechanics of the Spine. Today’s objectives…. Analyze structure vs. function of the spine Identify factors influencing mobility & stability of regions of the spine Identify the relationship between muscle location & its effectiveness on the trunk

shilah
Download Presentation

PHED 386

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PHED 386 Biomechanics of the Spine

  2. Today’s objectives… • Analyze structure vs. function of the spine • Identify factors influencing mobility & stability of regions of the spine • Identify the relationship between muscle location & its effectiveness on the trunk • List mechanical contributions to common injury

  3. Structure of the spine • Vertebral column • Curved stack of 33 vertebrae • Movements: motion segments • Joints of the movement segment • Symphysis: bodies & discs • Gliding (diarthroses): facet joints

  4. Structure of the Spine • Vertebrae • Body, neural ring, processes • Processes provide MA for mms • Body size-function relationship • Spines & facet joint relationship • Facet joints assist in loading • Facet joint compression

  5. Structure of the spine • Intervertebral discs • Composition • Annulus fibrosus: collagen bands cross vertically at 30° to each other • Nucleus pulposus: 90% water + collagen & proteoglycans • Function • Bind vertebrae together • Allow for movement • Bear & distribute loads

  6. Structure of the spine • Mechanics of discs • Flexion, extension & lateral flexion forces • Rotation forces

  7. Structure of the spine • Compression forces • Water loss & sodium /potassium gain • Results in loss of ~2cm of height • Within first 30 minutes • Increased volume  stiffness • Theory: risk of disc injury early in day

  8. Disc nutrition • Blood supply to age 8 • Pumping action from position change • Negative aspect of fixed position • Affect of injury & aging

  9. Discs and aging • Reduced water absorption • Decreased shock absorbing • Abnormal movements between vertebrae • Loads assumed by other structures • Reduced spinal column height • Postural alterations

  10. Ligaments of the spine • Anterior longitudinal ligament • Posterior longitudinal ligament • Supraspinous ligament (ligamentum nuchae) • Short ligaments • Interspinous • Intertransverse • Ligamentum flavum**

  11. Spinal curves • Primary • Thoracic & sacral • Secondary • Cervical & lumbar • Life changes

  12. Postural & mechanical changes • ?? Wolff’s law • Lordosis • Associated w/weak abdominal mm’s & anterior tilt • Causes • Kyphosis • Cause (Scheuermann’s disease) • Population/s • Scoliosis • Lateral/rotational deformity • Causes

  13. Neck Normal Hypolordotic Military Kyphotic S-Shaped Lower Back

  14. Movements of the spine • Flexion, extension, hyperextension • Greatest in cervical & lumbar regions • Lateral flexion & rotation • Greatest in cervical • Least in lumbar

  15. Muscles of the spine • Complex arrangement • Naming • Pairs • Unilaterally or bilaterally

  16. Muscles of the spine • Anterior (cervical region) • Pre-vertebral muscles • Rectus capitus anterior & lateralis • Longus capitus • Longus colli • Hyoid muscles – 8 pairs • Bilateral tension: flexion of the head • Unilateral: lateral flexion or rotation

  17. Muscles of the spine • Anterior • Abdominals • Rectus abdominus • External obliques • Internal obliques • Bilateral tension: flex spine, reduce anterior tilt • Unilateral tension: lateral flexion, rotaion • Abdominal wall function

  18. Muscles of the spine • Posterior • Cervical • Spenius capitus • Splenius cervicis • Assisted by smaller/deeper mms • Thoracic & lumbar • Errector spinae • Sacrospinalis, semispinalis, • Spinalis, longissimus, iliocostalis • Deep spinal mms Primary extensors

  19. Muscles of the spine • Lateral • Sternocleidomastoid (antagonistic) • Scalenes • Lumbar region • Quadratus lumborum • Psoas major

  20. Loads on the spine • Forces acting on • Body weight • Tension in ligaments • Muscles tension • Intra-abdominal pressure • External loads • Axial loading • Spinal compression

  21. Loads on the spine • Effect of center of gravity • Role of spinal extensor mms • Effect of actual forward bending or arm position • Spinal mms have very small moment arms  must generate large forces • Increased compression forces on lumbar spine

  22. Loads on the spine • Shear forces on spine • On lumbar spine in standing position • Increases during flexion & hyperextension • Contributor to disc herniation

  23. Loads on the spine • Flexion relaxation phenomenon • Tension in extensors increases w/flexion • At full flexion – extensor tension disappears • Flexion torque supported by posterior spinal ligaments • But increased shear from tension in interspinous ligaments • Also increased facet loading

  24. Loads on the spine • Lateral flexion and rotation • Role of movement speed

  25. Common injuries • Low back pain • 75-80% of population • Second only to common cold • Most frequent/expensive of workman’s comp claims • More prevalent in males • Causes: • Children – strains & sprains • Adults – • Sitting for prolonged periods/unable to sit at all • Unnatural postures • Sudden unexpected motions • Weak abdominal muscles

  26. Common injuries • Soft tissue • Contact or overload • Spasm response • Acute fractures: • forceful contraction of mms • Contact: direct or indirect • Large compressive loads

  27. Common injuries • Stress fractures • Spondylolysis • Spondylolisthesis • From repeated axial loading while hyperextended

  28. Common injuries • Disc herniations • Bulging, slipped, ruptured • Protrusion of pulposus from annulus • Common locations cervical & lumbar

More Related