NSI Protection & Vasculature

• Dorsal: toward the top of the brain or the back of the spinal cord
• Ventral: toward the bottom of the brain or the front of the spinal cord
• Rostral: towards the front of the brain or the top of the spinal cord
• Caudal: toward the back of the brain or bottom of the spinal cord
• CNS = brain + spinal cord
• Peripheral NS = everything else
• Sensory = info to brain
• Motor = info from brain
• Neurons

  • Transmit information
  • Myelinated cells transmit signals faster
  • Types:
  • Motor neuron
  • Sensory neurons
  • Interneurons
• Neuroglia

  • Nonneuronal, non excitable cells
  • 5x as abundant as neurons
  • Support, insulate and nourish neurons
• CNS neuroglia: oligodendroglia, astrocytes, ependymal cells and microglia
• PNS neuroglia: satellite cells, Schwann cells
• Multipolar neurons

  • Afferent
  • Found in ANS, skeletal muscle control + interneurons
• Pseudounipolar Neurons

  • Efferent
  • Found in sensory signaling
• Ependymal cells: line fluid filled areas within brain (e.g. ventricles)
• Microglia: resident immune cells
• Astrocyte: maintain and form blood brain barrier and synaptic connection as well as homeostasis
• Myelination: myelinate cells to improve neuronal conduction 

  • CNS: oligodendrocyte
  • PNS: schwann cell
• CNS - oligodendrocyte

  • Forms several myelin sheath
  • Myelinates section of several axons
  • Does not regenerate
• PNS - Schwann cell

  • Forms one myelin sheath
  • Myelinates one section of an axon
  • Regenerates
• CNS Neuropathy

  • Multiple sclerosis
  • Slow progression
  • Life expectancy decrease 7-14 years, no cure but remission can occur
  • Oligodendrocytes wont repair themselves
  • Secondary demyelination due to high ratio of axons myelinated by a single oligodendrocyte
• PNS Neuropathy

  • Guillain-Barré Syndrome
  • Progression over days to weeks
  • 80-90% recover within 2-4 weeks
  • Schwann cells can dedifferentiate, proliferate and remyelinate bare axons over time and re-wrap around axon as it grows
• Info travels via neuronal axon as electric signal
• Synapse from chemical connection
• Myelin makes everything faster
• Gray matter

  • Nerve cell bodies
  • Connections (cells talking to each other)
  • CNS: cortex & nucleus
  • PNS: ganglion
• White matter

  • Myelinated axons
  • Transmission
  • CNS: tract & fascicle
  • PNS: nerve
• Bony protection

  • Skull
  • Vertebrae
• Brain & Spinal Cord Meninges

  • Supportive framework for vasculature
  • Protect CNS from mechanical damage alongside CSF

  1. Dura mater (thick exterior)
  2. Arachnoid mater
  3. Pia mater (thin interior)
• Meninges Layers (exterior to interior)

  1. Epidural space (arterial blood)
  2. Dura mater
  3. Subdural space (venous blood)
  4. Arachnoid mater
  5. Sub arachnoid space (CSF + cerebral arterial supply)
  6. Pia mater
• Dura mater

  • Dural sinuses = separation between endosteal and meningeal layers for venous blood
  • Dural folds/septa (2 layers of meningeal dura)
  • Falx cerebri
  • Tentorium cerebelli & falx cerebelli
  • Diaphragma sellae
• Sinus = opening between 2 layers of the dura

  • Ex. superior sagittal sinus
• Sinus blood flow

  1. Superficial veins
  2. Superior sagittal sinus/ inferior sagittal sinus
  3. Confluence of sinuses
  4. L/R transverse sinus
  5. L/R sigmoid sinus
  6. L/R internal jugular vein
  7. R brachiocephalic vein
  8. Superior vena cava
  9. Heart
• Cerebral Arterial Supply - Aortic arch

  • Starting at the heart - 3 vessels come off the aortic arch

  1.  Right brachiocephalic trunk → right common carotid + subclavian
  2. Left common carotid
  3. Left subclavian
• Cerebral Arterial Supply - Carotid + Vertebral Arteries

  • Common carotid splits into the internal + external @ the carotid sinus
  • External = superficial (face)
  • Internal = deep (brain)
  • Subclavian → vertebral
  • Travels in transverse foramen of cervical vertebrae
• Cerebral Arterial Circle - Circle of Willis

  • Vertebral arteries join together @ pons to for basilar artery
  • Internal carotid artery + basilar artery join together to form circle
  • Along with communicating artery 
  • 3 major arteries supply the brain: anterior, middle + posterior cerebral
  • Big anastomosis = collateral blood supply ( but only in the circle)
• Stroke

  • Interruption of blood flow to the brain
  • Symptoms depend upon the area affected
  • 2 kinds: ischemic and hemorrhagic
  • Treatment depends upon the type of stroke
• Ischemic stroke

  • Blockage
  • Arthrosclerotic blood vessel
  • Treatment: anticoagulants
• Hemorrhagic stroke

  • Rupture (blood vessel)
  • Treatment: stop the bleed
• Ventricles: large CSF filled cavities in the brain