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Vertebral Column

Vertebral Column

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Vertebral Column

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  1. Vertebral Column Avinash Bharadwaj Human Structure and Development 212 Week 3 Semester 1, 2004

  2. A Long Story • From a stiff internal support (notochord)… • … “uniform” vertebral column of fishes… • …specialisations for terrestrial life • … to the erect human column. • Did it all begin with locomotor needs? • Locomotion in fishes and humans – little simlarity if at all! • How evolution uses available resources!

  3. The Human Vertebral Column C • Cervical (cervix = neck) • Thoracic • Lumbar • Sacrum • Coccyx T L S Co

  4. Curvatures “Head holding” Primary and Secondary Sitting Standing Walking

  5. A Generalised Vertebra • Weight bearing • Protection for spinal cord • Attachments for muscles and ligaments Superior Lateral

  6. A Generalised Vertebra • Neural Arch • Spine • Lamina • Transverse Process • Pedicle • Body Developmental terminology slightly different!

  7. A Generalised Vertebra • Articular processes and facets • Notches

  8. A Generalised Vertebra • Canal • Spinal cord and nerves • Meninges

  9. Regional Features C • Canal • Transverse process • Foramen • Costal and transverse elements • Spine T L Do not memorise now! Lab exercise!

  10. Atypical Vertebrae • Transitional areas • C 1 and 2, C 7 • Upper and lower thoracic • L 5

  11. Joints • Zygapophysial (facet joints – synovial) • Intervertebral discs (symphyses) • Ligaments • Locations and names • Also note intervertebral foramina

  12. The Intervertebral Disc • Annulus fibrosus • Nucleus pulposus White fibrocartilage Deformable tissue

  13. Movements • Limitations and summation • The “motion segment” (Unit of movement) • Flexion and extension • Lateral flexion • Rotational movement • Torsion of the disc • Orientation of facets

  14. Muscles • “Extrinsic” : Belong to the limbs • Intrinsic • Long and short • Superficial and deep • Many segments / few segments / one segment • Spine to spine / spine to transverse process / transverse pr. to transverse process • Unilateral (one-sided) / Bilateral actions • Once more… concept vs detail

  15. Muscles

  16. Development • Paraxial mesoderm • Segmentation – somites • More somites than ‘visible’ segments • Occipital region  caudal end • (…pre-occipital region…) • Somite • Sclerotome • Dermomyotome

  17. A A A B B B C C C Segmental Sclerotomes • Each vertebra : Two segments • Nerves are segmental • Arteries are intersegmental

  18. Comparative Features • Beware of generalisations! • Vertebrae : Complex structures • Invertebrate locomotion • Muscle contraction  shortening of body • Notochord • Stiffness : flexion of body • Vertebrae • Greater strength • Levers for muscles

  19. Fishes • Buoyancy • Uniform vertebral structure – well, almost! • No “neck”

  20. Amphibia • Gravity and limbs • Single cervical vertebra • “Trunk” vertebrae • Single sacral vertebra

  21. Reptiles • Terrestrial • Distinct neck • Stronger limbs • Tremendous variation

  22. Birds • Rigid back • Number of fused trunk vertebrae • Long neck • 15 – 20 vertebrae

  23. Mammals • Regional specialisation • Epiphyses (?Embryonic source) • 7 Cervical vertebrae as a rule • Approx 20 trunk vertebrae • Thoracic • Lumbar • Swingers and jumpers • Thoracic and lumbar proportions • Human vertebral column and other primates Thank You