4 Ventricular System Of The Brain Flashcards
Name the four brain ventricles.
CSF is produced in the ________ plexus.
Disruption of CSF circulation causes ___________
Two later ventricles
Third ventricle
Fourth ventricle
Choroid
Hydrocephalus
(LO) Changes during infection: Bacterial//Viral//Fungal
Predict what happens to CSF with each of the above for: pressure appearance protein glucose WBC count WBC type gram stain
Pressure: increase//normally or slight increase//increase
Appearance: turbid//clear//fibrin web
Protein: very high//increase//increase
Glucose: low//normal to slight decrease// NA
WBC count: very high//increase//increase
WBC type: neutrophils//monocytes//monocytes
Gram Stain: (+)//(-)//Yeast
(LO) If there is blood in your first sample of CSF, how can you distinguish whether it is caused by your needle insertion or by a hemorrhage that occurred prior to your needle insertion?
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At what precise vertebral levels is a lumbar puncture (spinal tap) performed and why is this level chosen? Why not at higher vertebral levels? What spinal cord structures are present at this level? (For these questions, you may need to review what you learned during Gross Anatomy or consult Haines or Willard.) In which meningeal layer or space is the needle sitting when withdrawing CSF?
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(LO) What clinical problem does the term “pseudotumor cerebri” refer to?
- a disorder associated with obesity and oral contraceptives
- pt presents with headache, visual disturbances (including diplopia), and papilledema
- increase in ICP
- often no identified cause and may be mistaken as a psychological dysfunction (8-10x more common among women).
(LO) What are some symptoms or signs of hydrocephalus? Does it make sense to you that these signs can occur? Why does hydrocephalus cause these symptoms or signs?
(Blockage of CSF by tumors of the choroid plexus, leads to expansion of ventricles)
- Pt presents with the characteristic triad: headache, nausea/vomiting, and papilledema (except in normal pressure hydrocephalus)
- Changes in consciousness (from being sleepy to coma)
- brain herniation-uncal or cerebellar tonsil. Results in life-threatening brain stem compression.
(LO) What is the most common cause of hydrocephalus?
Explain the different definitions of the terms communicating hydrocephalus vs. non-communicating hydrocephalus.
Explain the meaning of “hydrocephalus ex vacuo”. Explain the meaning of the term “normal pressure” hydrocephalus.
Most common: result of blockage of CSF circulation (just inside vs. outside for the difference in type)
Communicating: ventricles still communicate, blockage occurs outside.
Non-communicating: a blockage within the ventricles (aqueduct).
“ex vacuo” refers to damage to the brain caused by stroke or injury, resulting in an actual shrinkage of the brain size. CSF quantity is more than usual, but CSF pressure is normal.
“normal pressure” is mainly seen in the elderly population and in roughly half the cases there is an idiopathic intermittent increase in ICP. Results from decreased resorption of CSF at the arachnoid granulations. Classic presentation: “wet, wacky, and wobbly.”
(LO) How is CSF drained from the subarachnoid space? Where does this drainage go?
What would the consequences be if this drainage mechanism was blocked (e.g. by bacteria or blood cells from a subarachnoid hemorrhage)?
Where would excess CSF build up? Would intracranial pressure change?
- arachnoid granulations (largest in superior sagittal sinus) protrude into the venous sinuses of the brain and allow the CSF to exit the subarachnoid space and enter the blood stream.
- is drainage mechanism is blocked, CSF is still produced, which increases pressure and ultimately leads to the expansion of the ventricles at the expense of the surrounding brain (=hydrocephalus).
(LO) Where would excess CSF volume accumulate if a blockage of CSF flow occurred at the interventricular foramina?
If a blockage of CSF flow occurred at the cerebral aqueduct? If a blockage of CSF flow occurred at the foramina of Lushka and Magendie? Would intracranial pressure change in these scenarios?
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(LO) Describe the directional flow of CSF through the ventricular system, starting at the lateral ventricles and ending at the arachnoid granulations. Describe how CSF in the subarachnoid space is removed.
Lateral ventricles -> third ventricle -> fourth ventricle -> subarachnoid space -> venous sinuses
(removed from subarachnoid space via arachnoid granulations through the dura mater and protrude into venous sinuses and enter blood stream. These arachnoid granulations also serve as one-way valves)
What is the adaptive purpose of turning over the entire volume of CSF multiple times a day?
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(LO) What is the normal composition of CSF? What items in blood are filtered out during CSF secretion into the ventricles?
… what
(LO) What is the meaning of the term “Blood-CSF Barrier”? What cells help form this barrier?
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(LO) What is choroid plexus? In what parts of the ventricular system is it found? Describe the histological components of the choroid plexus. Are endothelial cells within the choroid plexus fenestrated or non-fenestrated? How is cerebrospinal fluid (CSF) produced and secreted?
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(LO) Describe the neuroanatomical locations (major brain region) of each ventricle and ventricular structure, i.e. the lateral ventricles, the interventricular foramina, the third ventricle, the cerebral aqueduct, and the 4th ventricle. Describe where CSF moves from inside the ventricular system to the subarachnoid space.
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