Unit 5: Ventricles Flashcards

1
Q

Lateral Ventricles (Brain Ventricles- Location)

A

Within the cerebral hemisphere

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2
Q

Frontal Anterior Horn (Brain Ventricles- Location)

A

Begins anterior to the intraventricular foramen of monroe and extends to the frontal lobe

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3
Q

Body (Brain Ventricles- Location)

A

Posterior to the intraventricular foramen of Monro, within the frontal and parietal lobes

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4
Q

Atrium/Trigone (Brain Ventricles- Location)

A

Area of convergence of the occipital horn, the temporal horn, and the body of the lateral ventricle

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5
Q

Occipital (posterior) Horn (Brain Ventricles- Location)

A

Extends from the atrium posteriorly into the occipital lobe

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6
Q

Temporal (inferior) Horn (Brain Ventricles- Location)

A

Extends from the atrium inferiorly into the temporal lobe

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7
Q

Third Ventricle (Brain Ventricles- Location)

A

Within the thalamus and hypothalamus

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8
Q

Fourth Ventricle (Brain Ventricles- Location)

A

Within the pons, medulla, and cerebellum

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9
Q

Ventricles

A

The neural plate comes together to form the neural tube that becomes the ventricular system

  • There are 4 cavities in the brain called the ventricles and are filled with cerebrospinal fluid
  • All one piece that encompass the brain and spinal cord
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10
Q

The 4 ventricles are:

A
  • 2 lateral ventricles
  • 1 third ventricle (surrounded by thalamus (diencephalon) 1/2 on each side)
  • 1 fourth ventricle (btw brainstem and cerebellum, specifically pons and medulla)
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11
Q

The Ventricles (image)

A
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12
Q

Interventricular Foramen of Monro

A

Location where lateral ventricle switches to 3rd ventricle

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13
Q

Cerebral Aqueduct

A

Location where 3rd ventricle switches to 4th ventricle

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14
Q

Flow of CSF

A
  1. Lateral Ventricles
  2. Foramen of Monroe/Intraventricular Forament)
  3. Third Ventricle
  4. Aqueduct of Sylvius
  5. Fourth Ventricle
  6. Medial: Foramen of Magendie, Lateral: Foramen of Luschka
  7. Flows around the spinal cord and in and around the brain in the subarachnoid space
  8. Exits through arachnoid granulations which poke into the superior sagittal sinus
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15
Q

Pathway of CSF out of 4th Ventricle

A
  • Foramen of Magendie (medial)

- Foramen of Lushka (lateral)

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16
Q

Choroid Plexus

A

Made up of ependymal cells which produce CSF and assist in circulating it by the movement of their cilia
-The choroid plexuses are constantly producing CSF creating a small pressure gradient

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17
Q

Function of CSF

A
  • Buoyancy
  • Cushioning
  • Cleaning
  • Ionic Balance
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18
Q

Choroid Plexus (image)

A
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19
Q

Cisterns

A

Large pockets in the subarachnoid space
-Quadrigeminal Cistern, Callosal Cistern, Interpenduncular Cistern, Cisterna Magna, Premedullary Cistern, Prepontine Cistern

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20
Q

Cisterna Magna (cerebellar medullary cistern)

A

Found between the cerebellum and medulla (between the inferior margin of the vermis and the posterior rim of the foramen magnum)

21
Q

Cistern in Lumbar Area of the Spine

A

This cistern is useful as it provides a place to extract cerebrospinal fluid through a lumbar puncture

  • A needle is placed between the lumbar vertebra and into this cistern
  • At this level of the spinal cord there are only spinal nerves and the fluid will help them “float” away
22
Q

CSF: things you may see in a chart

A
  • Pressure
  • VIsual exam
  • Chemistry
  • Immunology
23
Q

Normal Adult (CSF Fluid Profiles in Normal Adult and those with infectious meningitis)

A

White Blood Cells (per mm^3): <5-10, lymphocytes only
Protein (mg/Dl): 15-45
Glucose (mg/Dl): 50-100
Comments: If traumatic lumbar punctire, expect 1 additional white blood cell for every ~700 red blood cells

24
Q

Acute Bacterial Meningitis (CSF Fluid Profiles in Normal Adult and those with infectious meningitis)

A

White Blood Cells (per mm^3): 100-5000, usually polymorphonuclear leukocytes
Protein (mg/Dl): 100-1000
Glucose (mg/Dl): Reduced, <40
Comments: In patients with hyperglycemia, CSF glucose is abnormal if <50% of serum glucose

25
Viral Meningitis or "Aseptic Meningitis" (CSF Fluid Profiles in Normal Adult and those with infectious meningitis)
White Blood Cells (per mm^3): 10-300, usually lymphocytes Protein (mg/Dl): 50-100 Glucose (mg/Dl): Normal Comments: Glucose is occasionally reduced in herpes, mumps, or lymphocytic choriomeningitis virus
26
Herpes Meningoencephalitis
White Blood Cells (per mm^3): 0-500, usually lymphocytes Protein (mg/Dl): 50-100 Glucose (mg/Dl): Normal or reduced Comments: Red blood cells or xanthochromia
27
Tuberculosus Meningitis or Cryptococcal Meningitis
White Blood Cells (per mm^3): 10-200, usually lymphocytes Protein (mg/Dl): 100- 200 Glucose (mg/Dl): Reduced, <50 Comments:
28
CSF and Arachnoid VIlla
-CSF is constantly being produced and has a pressure gradient -CSF exits through Arachnoid Granulations -Arachnoid Granulations have 1 way valves to dump into the venous sinus (flowing in subarachnoid space as its flowing up and around the brain, arachnoid granulations extend out of the subarachnoid space and push up into the dura and out the venous sinus)
29
Hydrocephalus (Disorders of CSF System)
-Dialation of the ventricles by two degrees Caused by: -Blocked CSF circulation -Impeded CSF absorption -Too much production (could be caused by tumor) Result: -Pressure onto the corticobulbar and corticospinal tracts which results in increased weakness
30
Hydrocephalus (image)
31
Increased ICP (Disorders of CSF System)
Any increase in size of any sructure can cause an increase in ICP Ex. Diffuse cerebral edema, tumors, hemorrhage, obstruction of CSF flow, or a venous obstruction Symptoms include: Headache, nausea, bradycardia, hypertension, and loss of consciousness, and papilledema (pushing optic disc forward)
32
Common Symptoms and Signs of Elevated Intracranial Pressure
- Headache - Altered Mental Status (esp. irritability and depressed level of alertness/attention) - Nausea and vomiting - Papilledema - Visual Loss - Diploplia - Cushings Triad: Hypertension, bradycardia, and irregular respirations
33
Elevate head of bed 30° and maintain head straight to avoid obstructing jugular venous return (Treatment Measures for Elevated Intracranial Pressure)
-Promotes venous drainage | Time to onset of effect: Immediate
34
Intubate and hyperventilate to pCO2 of 25-30mm Hg (Treatment Measures for Elevated Intracranial Pressure)
-Causes cerebral vasoconstriction | Time to onset of effect: 30 seconds
35
IV Mannitol 1g/kg bolus, then 0.25g/kg every 6 hours, aiming for serum Na>138mEq/L and osmolarity 300-310 mOsm/L while maintaining normal volume status and normal blood pressure. Furosemide may also be added. (Treatment Measures for Elevated Intracranial Pressure)
-Promotes removal of edema and other fluids from CNS while maintaining cerebral perfusion Time to onset of effect: 5 minutes
36
Ventricular Drainage (Treatment Measures for Elevated Intracranial Pressure)
-Removal of CSF decreases intracranial pressure | Time to onset of effect: Minutes
37
If other measures fail, try barbiturate-induced coma (Treatment Measures for Elevated Intracranial Pressure)
-Causes cerebral vasoconstriction and reduced metabolic demands Time to onset of effect: 1 hour
38
Hemicraniectomy (Treatment Measures for Elevated Intracranial Pressure)
-Removal of skull overlying mass lesion -Decompresses intracranial cavity (experimental) Time to onset of effect: Immediate
39
Steroids (Treatment Measures for Elevated Intracranial Pressure)
-Reduces cerebral edema, possibly by strengthening blood-brain barrier -May also work by other mechanisms -Often used with brain tumors -Not shown to improve outcome in acute head trauma, stroke, or hemorrhage Time to onset of effect: hours
40
Lumbar Puncture
Used to check CSF, go in between L3 and L5
41
Venous Drainage of Brain
- The CSF diffuses through the arachnoid granulations and is reabsorbed into the venous system. - The veins of the brain empty into Sinuses. - The sinuses are formed by the two layers of the Dura Mater. - There are no valves in the brain sinuses. - Drainage occurs from the Superior Sagittal Sinus into two Transverse Sinuses and into the Sigmoid Sinus. - This is a curvy sinus that then exits the skull as the internal jugular vein. - There is also an Inferior Sagittal Sinus that runs along the bottom edge of the Falx Cerebri heading back towards the Tentorium Cerebelli where it becomes the Straight Sinus and then joins the superior sagittal sinus.
42
Confluence of the Sinuses
The area where the superior, inferior and straight sinuses converge
43
Cavernous Sinus
Inferior and “sits” on the Sella Turcica of the skull - Surrounds the pituitary gland and cranial nerves (CN III, IV, part of V, and VI) and the internal carotid artery run through the sinus. - So, if there is an abnormality in venous return it could compress against these cranial nerves or artery. - This sinus drains posteriorly through the superior and inferior petrosal sinuses back to the Transverse sinus
44
Sinus (image)
45
Blood-Brain Barrier (B.B.B.) and Blood CSF Barrier (B.CSF.B)
B.B.B. 1) Tight junctions between the endothelial cells that line the capillary walls 2) Astrocytes abutting on the capillaries 3) Basement membrane B.CSF.B -Outmost Layer of Epithelial Have Tight Junctions
46
Systemic Capillary vs. Brain Capillary (image)
47
Higher-Uptake into Brain (Blood-Brain Barrier Openings)
- Thiopental (anesthetic) - Sulfonamide - Tetracyclines - Atropine - Glucose - L-DOPA
48
Lower-Uptake into Brain (Blood-Brain Barrier Openings)
- Phenobarbital (anticovusant) - Norepinephrine - Dopamine - Penicilin
49
Differential Diagnosis of Headache