Extra points

• 12 thoracic vertebrae


  Characterised by articulated ribs
• Articulated ribs

  • Ribs are separate bones and articulate via synovial joints with the vertebral bodies and transverse processes of the associated vertebrae
  • All vertebrae have rib elements, but in regions other than the thorax, these elements are small and are incorporated into the transverse processes
• Vertebral arch


  A structure that extends from the vertebral body and provides attachment points for muscles and articulation with adjacent bones
• Vertebral bodies

  • Increase in size inferiorly as the amount of weight supported increases
  • Continuous through the foramen magnum of the skull with the cranial cavity of the head
• Vertebral bodies increase in size


  As the amount of weight supported increases
• Pedicles


  Bony pillars that attach the vertebral arch to the vertebral body
• Laminae

  Flat sheets of bone that extend from each pedicle to meet in the midline and form the roof of the vertebral arch
• Pedicles


  Projections from the back of the vertebral body that join the laminae
• Articular processes

  • Located on the superior and inferior aspects of the pedicles, articulate with adjacent vertebrae
• Inferior articular processes

  Articulate with the superior articular processes of adjacent vertebrae
• Superior articular processes

  Articulate with the inferior articular processes of adjacent vertebrae
• Superior and inferior vertebral notches

  Notches on the superior and inferior surfaces of the pedicles, participate in forming intervertebral foramina
• Components of the vertebrae

  • Pedicles
  • Laminae
  • Articular processes
  • Superior and inferior vertebral notches
• Typical cervical vertebra

  • Vertebral body is short in height and square shaped when viewed from above and has a concave superior surface and a convex inferior surface
  • Each transverse process is trough shaped and perforated by a round foramen transversarium
  • The spinous process is short and bifid
  • The vertebral foramen is triangular
• Vertebra CI (the atlas)


  • Major distinguishing feature is that it lacks a vertebral body
  • When viewed from above, the atlas is ring-shaped and composed of two lateral masses interconnected by an anterior arch and a posterior arch
  • Each lateral mass articulates above with an occipital condyle of the skull and below with the superior articular process of vertebra CII (the axis)
  • The superior articular facets are bean-shaped and concave, whereas the inferior articular facets are almost circular and flat
  • The transverse processes of the atlas are large and protrude farther laterally than those of the other cervical vertebrae
• Development of vertebra CI (the atlas) and CII


  The vertebral body of CI fuses onto the body of CII during development to become the dens of CII
• There is no intervertebral disc between CI and CII
• The atlanto-occipital joint


  Allows the head to nod up and down on the vertebral column
• The dens


  Acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side
• The transverse ligament of atlas holds the dens in position
• The transverse processes of the atlas act as levers for muscle action, particularly for muscles that move the head at the atlanto-axial joints
• Axis

  • Characterized by the large tooth-like dens which extends superiorly from the vertebral body
  • The two superolateral surfaces of the dens possess circular impressions that serve as attachment sites for strong alar ligaments, one on each side, which connect the dens to the medial surfaces of the occipital condyles
• Alar ligaments check excessive rotation of the head and atlas relative to the axis
• Posterior surface of the anterior arch

  Has an articular facet for the dens
• Dens


  Projects superiorly from the vertebral body of the axis
• Transverse ligament of atlas

  Strong ligament that holds the dens in position
• Transverse ligament of atlas

  Spans the distance between the oval attachment facets on the medial surfaces of the lateral masses of the atlas
• Laminae and spinous processes

  Form a reasonably complete bony posterior (dorsal) wall for the vertebral canal in most regions of the vertebral column
• Components of the vertebral arches

  • Laminae
  • Spinous processes
• Regions of the vertebral column

  • Most regions
  • Lumbar region
• Gaps between adjacent laminae and spinous processes

  • Wide from vertebra LI to vertebra LV
  • Widened further by flexion of the vertebral column
• Flexion of the vertebral column


  Widens the gaps between adjacent laminae and spinous processes
• These gaps allow relatively easy access to the vertebral canal for clinical procedures
• Anulus fibrosus


  Outer ring of collagen surrounding a wider zone of fibrocartilage arranged in a lamellar configuration
• Anulus fibrosus


  • Limits rotation between vertebrae
• Nucleus pulposus


  Gelatinous center of the intervertebral disc that absorbs compression forces between vertebrae
• Zygapophysial joints


  The synovial joints between superior and inferior articular processes on adjacent vertebrae
• Articular capsule


  A thin articular capsule attached to the margins of the articular facets that encloses each joint
• Regions of the body

  • Cervical
  • Thoracic
  • Lumbar
• Zygapophysial joints in cervical regions

  • Slopes inferiorly from anterior to posterior
  • Shape facilitates flexion and extension