Spine Anatomy & Conditions Flashcards
How many vertebrae are there and what is its distribution
- 33 vertebrae - 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal
- 24 are separable vertebrae - individual movement
Discuss the mobility of each vertebral type
- Cervical and lumbar very mobile
- Most problems and symptoms in the body - neck and lower back pain
- Thoracic relatively immobile as ribs come out to limit movement
- Sacrum and coccyx immobile as fused vertebrae
Describe the properties of the vertebral body
- 10% cortical bone and 90% cancellous bone - decrease weight and allow other functions within vertebra
- Usually the main weight bearing part of the vertebra
- Major site of contact between adjacent vertebrae
- End plates - articular surfaces covered hyaline cartilage
- Linked to adjacent vertebral bodies by intervertebral discs
Describe the structure of the vertebrae
- 1 spinous process
- 2 transverse processes
- 2 superior articular processes (facets) interlock with the vertebra above
- 2 inferior articular processes (not shown) interlock with the vertebra below
- Lamina joins the transverse process to spinous process
- Laminectomy - removal of lamina and spinous process to increase foramen space
- Pedicle connects transverse process to body
- Lamina + pedicle = vertebral arch
Explain the properties of the intervertebral disks
- Mainly made of water, collagen and proteoglycans (hydrophilic properties to bind water)
- Account for 25% of the length of the vertebral column
- Lose height with age - lose water from disk causing loss of pressure
- Slightly wedge shaped - secondary curvature of spine
Explain the 2 types of collagen in intervertebral disks
- Annulus fibrosus - type 1 collagen forming lamellae of annular bands in varying orientation
- Major shock absorber
- Highly resilient under compression - stronger than vertebral body
- Largest avascular structure - no blood supply, use diffusion for nutrients
- Nucleus pulposus - type 2 collagen
- Changes in size throughout day and changes with age
State the functions of the vertebral column
- Protection - encloses and protects the spinal cord and cauda equina within the spinal canal
- Support - carries the weight of the body above the pelvis
- Vertebral bodies increase in size inferiorly as compression forces increase
- Sacral vertebrae - fused, widened & concave anteriorly to transmit weight of the body through pelvis to legs
- Axis - forms the central axis of the body
- Movement - has roles in both posture and movement
- Haemopoiesis - red marrow
Describe the contents that pass through the vertebral foramen and intervertebral foramen
- Vertebral foramen - spinal cord
- Intervertebral foramen - roots of spinal nerves, blood vessels
- Present only in cervical, lumbar and thoracic vertebrae
Describe the characteristic features of lumbar vertebrae
- Kidney shaped vertebral body
- Vertebral arch posteriorly and vertebral body anteriorly
- Vertebral foramen triangular
Describe the characterstic features of sacrum
- Collection of 5 fused vertebrae
- Upside down triangle
- Contains facets for articulation with pelvis at sacro-iliac joints
- Vertebral column continues along the core of the sacrum and ends at the fourth sacral vertebra as the sacral hiatus
- Central canal contains the cauda equina
Describe the characteristic features of coccyx
- Small bone which articulates with apex of sacrum
- Collection of 4 fused vertebrae
- Lack of vertebral arches so no vertebral canal (does not transmit spinal cord)
Describe the major joint in the spinal column
- Superior and inferior articular process connect to form facet joint
- Synovial joints
- Creates intervertebral foramen to create space for spinal nerve route
- Prevent anterior displacement of vertebrae - helped by ligaments
- Orientation of lumbar facet joints 45˚ - allows more flexion and extension but less rotation
List the major ligaments in the vertebral column and describe their location
- Anterior longitudinal ligament - anterior side of vertebral body
- Posterior longitudinal ligament - posterior side of vertebral body
- Ligamentum flavum - between lamina
- Interspinous ligament - between vertebral arches
- Supraspinous ligament - tips of spinous process
Explain the function of anterior longitudinal ligament
- Prevent hyperextension
- Mobile over intervertebral disks
- Stronger than posterior longitudinal ligament
- Runs from the tubercle of C1 to the sacrum
- Runs anterior to vertebral body
Explain the function of posterior longitudinal ligament
- Prevents hyperflexion
- Also runs throughout spinal cord
- Runs from body of C2 to the sacral canal
- Runs posterior to vertebral body - Dictate where disk prolapse occurs - rupture annulus occurs at lateral side of posterior longitudinal ligament
- Where most stress is after tear
Explain the function of ligamentum flavum
- Yellow in colour - high elastin content
- Between laminae of adjacent vertebrae
- Limit hyperflexion
Explain the function of interspinous ligament
- Relative weak sheets of fibrous tissue
- Join one spinous process to another (attach between processes)
- Increase stability of vertebral column by resisting excessive flexion
Explain the function of supraspinous ligament
- Attach to tips of adjacent spinous process
- Restrict hyperflexion
Explain the patterns of normal curvature in the spine
- Kyphosis - concave anteriorly
- Thoracic and sacral curvatures are primary kyphotic curvatures that develop during fetal period
- Lordosis - concave posteriorly
- Cervical and lumbar curvature are secondary lordotic curvatures that develop during childhood in association with lifting the head and sitting
Explain abnormal curvature of the spine
- In old age, secondary curvatures are lost
- Disks begin to lose curvature - develop senile kyphosis
- Pregnancy - exaggeration of lumbar lordosis
At what level does spinal cord end
L1-L2