Vertebral Column

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Vertebral Column

• Avinash Bharadwaj
• Human Structure and Development 212
• Week 3
• Semester 1, 2004

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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!

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The Human Vertebral Column
C

• Cervical (cervix neck)
• Thoracic
• Lumbar
• Sacrum
• Coccyx

T
L
S
Co
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Curvatures
Head holding
Sitting Standing Walking

• Primary and Secondary

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A Generalised Vertebra
Superior
Lateral

• Weight bearing
• Protection for spinal cord
• Attachments for muscles and ligaments

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A Generalised Vertebra

• Neural Arch
• Spine
• Lamina
• Transverse Process
• Pedicle

• Body

Developmental terminology slightly different!
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A Generalised Vertebra

• Articular processes and facets
• Notches

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A Generalised Vertebra

• Canal
• Spinal cord and nerves
• Meninges

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Regional Features
C

• Canal
• Transverse process
• Foramen
• Costal and transverse elements
• Spine

T
L
Do not memorise now! Lab exercise!
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Atypical Vertebrae

• Transitional areas
• C 1 and 2, C 7
• Upper and lower thoracic
• L 5

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Joints

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

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The Intervertebral Disc

• Annulus fibrosus
• Nucleus pulposus

White fibrocartilage Deformable tissue
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Movements

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

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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

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Muscles
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Development

• Paraxial mesoderm
• Segmentation somites
• More somites than visible segments
• Occipital region ? caudal end
• (pre-occipital region)
• Somite
• Sclerotome
• Dermomyotome

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Segmental Sclerotomes

• Each vertebra Two segments
• Nerves are segmental
• Arteries are intersegmental

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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

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Fishes

• Buoyancy
• Uniform vertebral structure well, almost!
• No neck

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Amphibia

• Gravity and limbs
• Single cervical vertebra
• Trunk vertebrae
• Single sacral vertebra

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Reptiles

• Terrestrial
• Distinct neck
• Stronger limbs
• Tremendous variation

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Birds

• Rigid back
• Number of fused trunk vertebrae
• Long neck
• 15 20 vertebrae

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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