Kin 427 Week 2

• Functions of the spine

  • Supports and transmits physical loads
  • Shock absorption
  • Enables motion between skull and pelvis
  • Attachments for tendons and ligaments
  • Protects spinal cord
• Structure of the spine

  • C-spine - 7 vertebrae - lordotic
  • T-spine - 12 vertebrae - kyphotic
  • L-spine - 5 vertebrae - lordotic
• Functional Divisions of the spine

  • Vertebral body - provides axial rigidity
  • Posterior elements - constraints motion of vertebral body, attachment site
  • Pedicles - transmits mechanical loads between vertebral body and posterior elements
  • Pedicles - Form border of vertebral canal and intervertebral foramen (protects nervous tissue)
• Vertebral body


  • Two types: cortical bone (stiff brittle shell) and trabecular (spongy/cancellous bone)
  • Trabeculae enables elastic deformation of vertebral body
• Joints of Lumbar Spine

  • Inter-body joint (between vertebral bodies) - fibrocartilaginous joint
  • Facet (zygapophyseal joints - joints between articular processes) - synovial joint
• Facet joints


  • Limits rotation about longitudinal axis
  • Glides freely when bending forward (flexing)
  • Glides until impacting lamina (or spinous processes ["kissing spines"] when disc height lost) when bending backward (extending)
  • Limits anterior translation of superior vertebra (with respect to inferior vertebra)
• Lumbar Spine Ligaments


  • Supraspinous ligament is a continuation of the nuchal ligament
  • Ligamentum flavum is comprised mostly of elastin
• Components of Intervertebral Disc

  Endplates - hyaline cartilage that connect discs to vertebrae

  Annulus - sheets of collagen sandwiched between endplates

  Nucleus - hydrated gel that pressurized under load