1Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS (continued from Lesson 1)• Tentorium Cerebelli– A portion o...
2Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Cerebral Blood Flow– Cerebral blood flow is remarkably con...
3Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Cerebral Perfusion Pressure– The residual pressure that su...
4Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Intercranial Pressure– The pressure within the cranial vau...
5Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• The Body’s Reaction– As ICP increases CPP decreases, and t...
6Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• The Body’s Reaction– As blood flow and B/P increase, the I...
7Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Spinal Cord– The spinal cord is the body’s main communicat...
8Emergency Services, LLC / Copyright 2013Spinal NervesHands-On:Central Nervous System Training, Lesson 2COMPONENTS OF THE ...
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Central nervoussystem lesson2

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Central nervoussystem lesson2

  1. 1. 1Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS (continued from Lesson 1)• Tentorium Cerebelli– A portion of the dura mater that covers the cerebellum.– An opening within the tentorium at the junction of themidbrain and the cerebrum is called the TentoriumIncisura.– The brain stem is directly below and the third cranialnerves pass through the incisura.– If the tentorium incisura herniates due to increasedintracranial pressure, then the third cranial nerve will becompressed.– Further inferior herniation will compress the tenth cranialnerve.Hands-On:Central Nervous System Training, Lesson 2
  2. 2. 2Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Cerebral Blood Flow– Cerebral blood flow is remarkably constant despitechanges in blood pressure.– However, it begins to decrease when the mean arterialpressure drops below 60mmHg.• Mean Arterial Pressure– MAP = diastolic pressure + 1/3 pulse pressure– Pulse pressure = systolic - diastolic– B/P 120/80, MAP = 80 + 1/3(40)– MAP = 93 mmHgHands-On:Central Nervous System Training, Lesson 2
  3. 3. 3Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Cerebral Perfusion Pressure– The residual pressure that supplies and distributes bloodflow in the brain (CPP).– CPP = MAP - ICP– As ICP increases, the CPP drops.– As MAP decreases, the CPP drops.– Our goal is to maintain adequate MAP and decreaseICP to maintain an adequate CPP.Hands-On:Central Nervous System Training, Lesson 2
  4. 4. 4Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Intercranial Pressure– The pressure within the cranial vault.– Any time that pressure is increased in an enclosedvessel, the pressure is transmitted equally throughout theinternal surface of the enclosed vessel. (Pascal’sPrinciple).– Matter that is moved with pressure will move in the pathof least resistance.– Causes of increased ICP:• Cerebral Edema (swelling)• Cerebral HemorrhageHands-On:Central Nervous System Training, Lesson 2
  5. 5. 5Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• The Body’s Reaction– As ICP increases CPP decreases, and the brain is forcedinto anerobic metabolism due to hypoxia.– The initial response is to activate the cardiovascularsystem to increase blood pressure and increase bloodflow.– Respirations increase in order to keep up with increasedblood flow.– If ICP continues to rise then the brain will have no choiceexcept to herniate through the tentorium or the foramenmagnum, or both (path of least resistance).Hands-On:Central Nervous System Training, Lesson 2
  6. 6. 6Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• The Body’s Reaction– As blood flow and B/P increase, the ICP will alsoeventually increase due to the increased blood flow in theenclosed vessel. There will then be a decrease in thepatient’s heart rate.• Cushing’s Triad– Rising blood pressure– Change in respiratory pattern– Decrease in pulse rate– Cushing’s triad should be recognized to be a clear butlate sign of rising intracranial pressure.Hands-On:Central Nervous System Training, Lesson 2
  7. 7. 7Emergency Services, LLC / Copyright 2013COMPONENTS OF THE CNS• Spinal Cord– The spinal cord is the body’s main communicationconduit. It carries commands to and from the brain,collecting and dispersing them through the peripheralnervous system.SpinalCord&ComponentsHands-On:Central Nervous System Training, Lesson 2
  8. 8. 8Emergency Services, LLC / Copyright 2013Spinal NervesHands-On:Central Nervous System Training, Lesson 2COMPONENTS OF THE CNS

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