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12.11.06 Teaching notes

Radiology - Haemorrhage
  • Intra-axial
    • i.e. Parenchymal
  • Extra-axial
    • Extradural
      • Usually from middle meningeal artery
      • Bi-concave
        • Lens shape
      • Never crosses suture lines
      • Strips dura away
      • Check for a fracture!
    • Subdural
      • From bridging veins
      • Crosses sutures
      • Tracks dural reflections - Look for "blood lines" - high intensity lines
        • Falx cerebri
        • Tentorium cerebelli
      • Crescent shape
      • Common in older people
        • Contraction => More subdural space => Longer bridging veins
    • Subarachnoid
      • From arteries
      • Basal cisterns highlighted
      • Sulci, sylvian fissure highlighted


Peripheral neuropathies

  • Mononeuritis multiplex
    • Ssimultaneous or sequential involvement of individual noncontiguous nerve trunks, either partially or completely
    • Evolves over days to years
    • Typically presents with acute or subacute loss of sensory and motor function of individual nerves
    • The pattern of involvement is asymmetric
  • Mononeuropathy
  • Peripheral polyneuropathy
    • Sensory 
    • Motor
    • Sensory-motor polyneuropathy


Median nerve
  • Thenar muscles
    • Opponens policis
      • Make a ring between thumb + little finger
    • Abductor policis brevis
      • Lift up + resist
    • Flexor policis brevis
      • Flex over palm + resist
  • Anterior interosseous nerve
    • Supplies terminal flexors of thumb + index finger
      • CRUCIAL for writing etc.
    • Isolate joint, flex + resist

Ulnar nerve
  • 1st dorsal interosseous
    • 1st thing to go => Check muscle bulk!
  • Forearm flexors
  • ALL the interossei
    • Hold piece of paper between fingers (both of you)
    • Pull apart
  • Damage:
    • Leaning on your elbow (protected only by skin)
    • Supracondylar fracture


Radial nerve

  • Extensors
    • HARD-CORE - Should not ever be able to overcome
  • => Posterior interosseous nerve => Finger extensors


Leg stuff

  • Meralgia paresthetica
    • Compression of lateral cutaneous femoral nerve of thigh
      • => numbness or pain in the outer thigh
    • Caused by entrapment or compression where it passes between the ilium and the inguinal ligament near the attachment at the ASIS
    • Causes:
      • Weight gain (belly roll)
      • Pistol
      • Tight underwear
  • Roots
    • L1,2,3 => Femoral
      • Check hip flexion + knee extension
      • c.f. buckling gait
    • L4,5,S1 => Sciatic
      • => Tibial nerve (posterior leg)
      • => Common peroneal nerve
        • => Superficial peroneal nerve (lateral compartment - peroneus longus and peroneus brevis)
        • => Deep peroneal nerve (anterior compartment -  tibialis anterior, EHL, EDL, peroneus tertius)
  • Common peroneal nerve wraps round the fibular head => Risk of injury


Falx cerebri / Tentorium cerebelli



Notes
  • Electrophysiology parameters
    • CV - Conduction velocity
    • DML - Distal motor latency
    • SL - Sensory latency
  • Put the muscle in action; Resist the action
  • Susceptibility to neuropathy
    • Diabetes
    • Hereditary neuropathy with liability to pressure palsies
      • Myelin deficiency due to peripheral myelin protein 22 mutation
    • Alcohol
    • Vitamin B12 deficiency
  • Median nerve entrapment in CTS occurs at the DISTAL CREASE OF THE WRIST
  • Femoral nerve runs ABOVE the inguinal ligament in 15% of people => Susceptible to injury
  • Sensory supply to the hand:

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