Chapter 2: CNS Support Structures

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Chapter 2: CNS Support Structures
2015-03-06 23:24:14
CNS Support Structures
NPTE: Chapter 2
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  1. Bony Structure
    • Skull (cranium)
    • Rigid bony chamber that contains the brain and facial skeletal 
    • Opening (foramen magnum) at its base
  2. Meninges
    • Dura mater: outer, tough, fibrous membrane attached to inner surface of cranium; forms flax and tentorium 
    • Arachnoid: delicate, vascular membrane
    • Subarachnoid space: formed by arachnoid and pia mater; contains CSF and cisterns, major arteries
    • Pia mater: thin, vascular membrane that covers the brain surface
  3. Ventricles
    • 4 cavities/ventricles that are filled with CSF
    • Communicate with each other and with SC canal
  4. Lateral Ventricles
    • Large, irregularly shaped
    • Has anterior (frontal), posterior (occipital) , and inferior (temporal) horns
    • Communicates with third ventral through foramen of Monro
  5. Third Ventricle
    • Located posterior and deep between the 2 thalami
    • Communicates with 4th ventricle through cerebral aqueduct
  6. Fourth Ventricle
    • Pyramid-shaped cavity located in pons and medulla
    • Foramina (openings) of Luschka and Magendie communicate with 4th ventricle through subarachnoid space
  7. Cerebrospinal Fluid
    • Provides mechanical support (cushions brain)
    • Controls brain excitability by regulating ionic composition
    • Aids in exchange of nutrients and waste products 
    • Produced in choroid plexuses in ventricles
  8. Blood-Brain Barrier
    • Selective restriction of blood-borne substances from entering CNS
    • Associated with capillary endothelial cells
  9. Blood Supply
    • Brain is 2% of body weight with a circulation of 18% of total blood column
    • Carotid System
    • Vertebrobasilar System
    • Circle of Willis
    • Venous Drainage
  10. Carotid System
    • Internal carotid arteries
    • Arise off common carotids
    • Branch to form anterior and middle cerebral arteries
    • Supply large area of brain and many deep structures
  11. Vertebrobasilar System
    • Vertebral arteries arise off subclavian artery
    • Unite to form basilar artery
    • Vessel bifurcates into 2 posterior cerebral arteries
    • Supplies brainstem, cerebellum, occipital lobe, and parts of thalamus
  12. Circle of Willis
    • Formed by anterior communicating artery
    • Connects 2 anterior cerebral arteries and posterior communicating arter, connecting each posterior and middle cerebral artery
  13. Venous Drainage
    Includes cerebral veins and dural venous sinuses