Vertebral column

  • Components
    • Intervertebral disc
    • Vertebrae
      • Cervical –7
      • Thoracic –12
      • Lumbar – 5
      • Sacral – 5
      • Coccygeal – 4
  • Curvatures
    • In the foetus & newborn
      • C shaped with an anterior concavity
    • In adults, 4 curvatures
      • cervical (secondary)
        • appears when infant raises his head
      • thoracic (primary)
      • lumbar (secondary)
        • appears when infant stands
      • sacral (primary)

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  • Parts of a typical vertebrae
    • Vertebral body
    • Vertebral arch
      • pedicle
      • lamina
    • Transverse processes
    • Spinous processes
    • Superior & inferior articular processes (zygapophyses)

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Regional features of the vertebrae

  • Cervical (like triangle)
    • In the transverse processes
      • transverse foramen
      • anterior & posterior tubercles
    • Atlas (C1)
      • no body & spine
      • 2 arches
      • paired lateral masses
    • Axis (C2)
      • dense (otondoid process) projects up from the body
      • bifid spine
  • Thoracic (like a clown face –tickle my ribs)
    • costal facets for articulation with the ribs
  • Lumbar (like an aeroplane)
    • large body
    • slender transverse processes
    • short, thick spines

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  • Sacrum
    • triangular shape
    • 5 sacral vertebrae fused
    • auricular surface articulate with hip bones
  • Coccyx
    • 4 coccygeal vertebrae fused

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Intervertebral disc

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  • lies between two vertebrae
  • Parts
    • outer
      • annulus fibrosus
      • fibrous
    • central
      • nucleus pulposes
      • semifluid
  • Functions
    • give flexibility
    • binds the vertebrae
      • secondary cartilaginous joint)
    • shock absorbers
  • Prolapsed intervertebral disc
    • nucleus pulposes escapes through annulus fibrosus posterolateraly
    • Press on the cauda equina and nerve roots
      • Give rise to neurological symptoms
      • Sciatica

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Joints of the vertebral column

  1. Joints of the vertebral bodies
  2. Joints of the vertebral arches
  3. Craniovertebral joints
  4. Costovertebral joints
  5. Sacroiliac joints

Joints of the vertebral bodies

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  • articular surfaces of adjacent vertebral bodies connected by
    • IV disc (symphyses)
  • no disc between
    • C1 & C2
    • sacral & coccygeal vertebrae
      • permits movements between adjacent vertebrae
  • Anterior longitudinal ligament
    • extends from – anterior surface of the sacrum
    • up til – C1 anterior tubercle & occipital bone
    • fused to vertebral bodies & IV discs
      • Prevents hyperextension of vertebral column
  • Posterior longitudinal ligament
    • extends from – sacrum
    • up til – C2
    • fused to IV discs & loosely to vertebral bodies
      • Prevents hyperflexion of vertebral column

Joints of the vertebral arches (zygopophysial/facet joints)

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  • synovial joints
  • between superior & inferior articular processes of adjacent vertebrae
  • loose joint capsule
  • movements depends on the shape & direction of the articular surfaces
  • movements
    • Cervical
      • facets are obliquely placed & horizontal
      • flexion, extension & lateral flexion
    • Thoracic
      • facets lie in an arc
      • rotatory movements
        • flexion & extension limited
    • Lumbar
      • joint line lies in the saggital plane
      • flexion, extension & lateral flexion
  • Ligameta flava
    • extends from the lamina above to lamina below
    • consists of yellow elastic tissue
    • prevents sudden flexion of vertebral column
    • helps to maintain the normal curvatures
  • Other ligaments (gives stability to the facet joints)
    • Interspinous ligaments
    • < ul>

    • between adjacent spines
    • Nuchal ligament
      • In the cervical region the supraspinous ligaments extend as a thick ligament
      • from C7 spine to external occipital protuberance
  • Supraspinous ligaments
    • from C7 spine to sacrum
      • no more spinal projections in coccyx
  • Intertransverse ligament
    • between adjacent transverse processes

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Craniovertebral joint

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  • Atlanto-occipital joint
    • Superior articular surface of the lateral mass of the atlas with the occiptal condyle
    • Permits nodding of the head (‘yes’ movement)
    • Anterior & posterior atlanto-occipital membranes
      • extends from the anterior & posterior arches of the atlas to margin of the foramen magnum
      • Prevents excessive movements of the joint

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  • Atlanto-axial joint
    • 2 lateral joints between the inferior surface of the lateral facet of the atlas & superior facet of axis
      • gliding type synovial joint
    • 1 median joint between the dense of the axis & anterior arch of the atlas
      • pivot type synovial joint
    • Moves head from side to side (‘ No’ movement)
    • Dense of the axis acts as the pivot
    • Transverse ligament of atlas
      • keeps the dense in position

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Sacroiliac joints

  • Between the sacrum & iliac bones
  • Synovial joint with limited movements
  • Strong sacrotuberous ligament
    • stabilizes the joint

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Muscles of the back

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  • Extrinsic back muscles
    • Superficial
      • trapezius
      • lattisimus dorsi
      • levator scapuli
      • rhomboids
    • Intermediate
      • serratus posterior superior
      • serratus posterior inferior

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  • Intrinsic back muscles
    • Superficial layer
      • splenius muscles
        • splenius capitis
        • splenius cervicis
      • function (neck)
        • lateral flexors
        • lateral rotators
        • extensors
    • Intermediate layer
      • erector spinae muscles
        • iliocostalis
        • longissimus
        • spinalis
      • Common origin from
        • iliac crest & sacrum
        • sacroiliac ligament
        • spines of sacral & lumbar vertebrae
      • Function
        • main extensor of vertebral column
    • Deep layer
      • transversospinal muscles
        • semispinalis
          • extends cervical & thoracic spine
        • multifidus
          • stabilizes the vertebrae
        • rotators
          • rotatory movement
  • All the muscles are extensors of the vertebral column
    • supplied by the posterior rami of the spinal nerve

Neck muscles

  • Suboccipital muscles
    • rectus capitis posterior major & minor
      • extend the atlanto-occipital joint
    • inferior oblique
      • rotates the atlantoaxial joint
    • superior oblique
      • extends atlanto-occipital joint (same)

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Movements of the vertebral column
Refer muscle diagram

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  • Atlanto-occipital joint
    • Flexion
      • Supra & infrahyoid muscle
      • Longus capitis
      • Sternocleidomastoid muscle
    • Extension
      • All suboccipital muscles
        • except inferior oblique
  • Atlanto-axial joint
    • Rotation
      • To same side
        • inferior oblique
        • rectus capitis
        • splenius capitis
      • To opposite side
        • sternocleidomastoid muscle
  • Cervical intervertebral joints
    • Flexion
      • Sternocleidomastoid muscle
      • longus coli
    • Lateral flexion
      • Scalene group
    • Extension
      • deep neck muscles
  • Thoracic & lumbar int
    ervertebral joints
    • Flexion
      • rectus abdominis
      • Psoas major
    • Extension
      • Erector spinae
    • Lateral flexion
      • Deep back muscles
      • External & internal oblique
      • Quadratus lumborum
    • Rotation
      • Deep rotators
      • External oblique

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Spinal canal (vertebral canal)

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  • Bounded by vertebral body & vertebral arch
  • Spinal cord lies in the spinal canal
    • covered by meninges
    • subarachnoid space
      • CSF
      • From lower border of L1 – S1
      • lumbar puncture between L3 & L4

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  • Internal vertebral venous plexus
    • Within the spinal canal
    • Communicate with external veins
    • No valves
    • Carcinoma can spread from distant sites to vertebral bodies

  • Intervertebral foramen
    • Bounded by
      • vertebral notches, body & intervertebral joint
    • Spinal ganglia located in it
    • Spinal nerve comes out through it
      • root compression occur here

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