Ch. 22: Vertebral Column

• vertebral body constructed of:

  • strong outer layer of cortical bone
  • hallow cavity reinforced by trabeculae
• anterior column:

  • vertebral bodies + IVD
  • shock-absorbing capabilities
• posterior column:

  • articular processes + facet joints
  • gliding mechanisms for movement
• IVD's contribute 20-25% of the length of the vertebral column
• spinal junctions:

  • craniovertebral: cervical spine + atlas, axis, + head
  • cervicothoracic: mobile cervical spine + stiffer superior thoracic segments
  • thoracolumbar: thoracic spine (rotation) + lumbar spine
  • lumbosacral: lumbar spine (flex + ext) + stiff sacroiliac joints
• amount of motion available in each region of the spine is determined by:

  • disk-height ratio
  • compliance of fibrocartilage
  • dimensions + shape of adjacent vertebral end plates
  • age
  • disease
  • gender
• type of motion is determined by:

  • shape + orientation of articulations
  • ligaments + muscles of segments
  • size + location of articulating processes
• flexion + extension:

  • flexion: anterior roll + glide
  • anterior portion of vertebral body approximates + spinous processes separate
  • extension: reverse actions
• side bending:

  • lateral edges of vertebral bodies approximal on side toward which spine is bending + compresses IVD
  • edges separate + IVD distracts on opposite side
• rotation:

  • vertebral body moves ipsilaterally
  • spinous process moves contralaterally
• fryette's first law:

  • when any part of the lumbar or thoracic spine is in neutral, side bending will be opposite of the side of rotation
• fryette's second law:

  • when any part of the spine is in a position of hyperextension or hyper flexion, the side bending of the vertebra will be to the same side as the rotation of that vertebra
• fryette's third law:

  • if motion in one plane is introduced to the spine, any motion occuring in another plane is restricted
• combined motions are used when a pt's symptoms are not reproduced using planar motions of flexion, extension, side bending, + rotation
• closing restriction: restriction of extension, side bending, + rotation to the same side of pain
• open restriction: restriction of flexion, side bending, + roatation to the opposite side of pain
• passive system:

  • vertebrae
  • IVD
  • facet joints
  • joint capsules + ligaments
  • load bearing units + source of passive stiffness
• active system:

  • muscles
  • uses stored elastic energy + level of activation or force
• CNS:

  • feedforward control to general active muscle stiffness
  • feedbackward control to augment muscle stiffness