L2.1 Back

Question 1

What are the borderes of the back?

Answer 1

• T1 → coccyx
• Medial scapula border
• Pos surfaces ribs
• Iliac crest

Question 2

What are the different curvatures of the back?

Answer 2

• 1o foetal C-shape
• 2o lordortic curve (due to muscles strengthening)
  
  • Cervical (~6-8months) – to keep head up
  • Lumbar (~12-15months) – for walking

Question 3

What are the vertebral abnormalities?

Answer 3

• Lordosis
• Kyphosis
• Scoliosis
• Cranial shift (features of vert shifted up – ribs on C7)
• Caudal shift (features of vert shifted down)

Question 4

What is the structure of a lumbar vertebrae?

Answer 4

• (articular surface – sagittal)
• Vertebral arch = pedicle (root) + laminar
• Site of potential injury: pars interarticularis → bilateral fracture → slip disc

Question 5

What is the structure of a thoracic vertebrae?

Answer 5

• (articular surface – Coronal)
• Essentially the same as lumbar
• Key difference: articular (demi) facets for joint attachment

Question 6

What is the structure of the sacrum & coccyx?

Answer 6

• (articular surface – Coronal)
• Fusion of vertebra (no discs in between)
  
  • Fuse from below up
• Different articular orientation → stops L5 from slipping forward
• Foraminae → for nerve roots & vessels (esp. sacral veins)
• Canal hiatus → gap between sacrum & coccyx

Question 7

What veins drain the vertebrae?

Answer 7

• Basivertebral veins: drain vert bodies → internal vertebral venous plexus (outside dura) → external vertebral venous plexus (outside vertebral canal)

Question 8

What are, and how many centres of ossifications do vertebrae have?

Answer 8

• 3 primary centres
  
  • In body and each vertebral arch (aka neural arch)
• 5 secondary centres
  
  • Tips of spinous and transverse process + upper & lower meninges of body (annular epiphysis)
  • Closes during adolescence when vertebral column growth is complete
    
    • There is a growth plate at the tips – may mistake for fractures

Question 9

What are the vertebral growth anomalies?

Answer 9

• Partial failure of formation – Wedge vertebrae
• Complete failure of formation – Hemi vertebrae
• Unilateral failure of segmentation – Congenital bar
• Bilateral failure of segmentation – Block vertebrae
• Spina Bifida (~L2-4)
  
  • Occulta (may have no significance)
  • Cystica → a sac
    
    • Meningocele (just meninges)
    • Meningomyelocele (contains neural tissues)

Question 10

What is the function of the IV disc?

Answer 10

• Nucleus pulposus: incompressible but deformable → keeps vertebrae apart
  
  • Made up of water (mucus texture in children)
• Annulus fibrosus: Attaches below/above vertebral body → keeps vertebrae tgt
  
  • Laid down perpendicular to each other
  • Twisting while lifting dangerous → only 50% fibres can resist load

Question 11

What are the 2 main ligaments of the vertebrae?

Answer 11

• Posterior longitudinal: Back of vertebral body, within vertebral canal
  
  • Fans out at each IV disc → directs herniation pos-laterally over ligament
    
    • ∴ Herniation → impinges on nerve root below
      
      • E.g. herniation between L4 & 5 → impinge on L5 nerve root
• Ligamentum flavum: has elastic connective tissues (allows flexion)
  
  • Becomes more fibrous (thickens) with age → encroaches into canal → impinge neural structures in canal

Question 12

What are the joints of the vertebrae innervated by?

And which structures are aneural/avascular?

Answer 12

• Branches of the POS rami (also supplies overlying skin)
• Synovial joint: capsule has blood & nerve supply
• Hyaline cartilage avascular & aneural

Question 13

What is the vertebral canal and what does it contain?

Answer 13

• Terminates at L1-2 in adults (Cauda Equina)
• Meninges around the spinal cord
• Contains:
  
  • BV internal venous plexus
  • Vertebral column (longer than cord)
    
    • Cord finishes at L1 but dura mater finishes at S3 → leaves space called lumbar cistern → point where needle injected to extract CSF

Question 14

What does the intervetebral foramen contain?

Answer 14

• Dorsal root ganglion
• Nerve root
  
  • Located in the upper part (inferior vertebral notch) of the foramen

Question 15

What are the superficial muscles of the back?

Answer 15

• (Innervated by ANT rami)
• Attaches to and act on the UL
• Trapezius (not innervated by ANT rami)
  
  • innverated by the 11th cranial (Sternocleidomastoid also)
• Lat dorsi
• Rhomboids
• Levator Scapulae

Question 16

What are the deep muscles of the back?

Answer 16

• (Innervated by POS rami)
• Erector Spinae (Med to Lat – across 5-7 vertebral segments)
  
  • Prime movers, returning flexed trunk to upright posture (extended)
    
    • *Contracts eccentrically doing toe touch*
  • Eccentrically ‘quiet’ during full flexion → Dangers of lifting flexed
• • Spinalis (closest to the spine)
    
    • Longissimus (longest)
    • Illiocostalis (From iliac crest)
• Transversospinalis (Lat to Med - short segmental muscles)
  
  • Short segmental stabilisers (across 2 vertebra)
  • Pain → inhibits muscle contract
  • Lower back pain inhibits muscle contraction → deep muscles could go to wastage
    
    • Transversus abdomalis (resist tension from ab viscera) usually contracts to stabilises the back muscles
      
      • Due to connection between lumbar fascia
      • ∴ strengthen deep ab muscles → strengthens deep back muscles