08 26 2014 Meninges and Ventricals Flashcards

1
Q

Cerebral Spinal fluid

A

Clear, colorless liquid
140mL
Provides buoyancy, and protects against sudden movements.

Some antibacterial properties

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2
Q

Cisterns

A

Enlarged areas of subarachnoid space (around brain stem)

  • Perimesencephalic cisterns
  • Prepontine cistern
  • cisterna magna
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3
Q

perimesencephalic cisterns

A

Interpeduncular cistern (ventral and abovepons)

Quadrigeminal (and ambient) cisterns (between corpus collusum and cerebellum and pons)

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4
Q

Prepontine cistern

A

ventral to pons (aka in front of pons)

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5
Q

Cisterna magna

A

below cerebellum

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6
Q

Why do you use a lumbar puncture?

A

Diagnose subarachnoid hemorrhage and meningitis or introduce drugs.

Adults: L3-L4
Children: L4-L5

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7
Q

What is normal pressure of CSF

A

< 20 cm H2O

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8
Q

Layers of Dura in Brain vs. spinal cord?

A

Brain: 2 layers
-periosteal and meningeal – split to form sinuses

Spinal cord : 1 layer – meningeal (vertebrae have their own periosteum)

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9
Q

Layers of Arachnoid in brain vs. spinal cord?

A

Brain: arachnoid trabecular and many cisterns

Spinal cord: fewer travecule and 1 cistern (lumbar cistern)
- this is where you do lumbar puncture

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10
Q

Layers of Pia in brain vs. spinal cord?

A

Spinal cord: forms denticulate ligaments and filum terminal

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11
Q

Denticulate Ligament of spinal cord?

A

anchor pia to dura (from pia to dura)

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12
Q

Filum Terminum of spinal cord?

A

anchors spinal cord to arachnoid.

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13
Q

Coccygeal ligament (filum terminale externum) of spinal cord?

A

anchors spinal cord to coccyx

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14
Q

What are the dural folds?

just name them

A

Invaginations of inner dural layer. Create the supratentorial and infratentorial spaces (in reference to tentorium)

  1. Flax cerebri
  2. Falx cerebelli
  3. Tentorium cerebelli
  4. Diaphragm sellae
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15
Q

Falx cerebri

A

in between cerebral hemispheres (in longitudinal fissure)

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16
Q

Falx cerebelli

A

separates cerebellum in right vs. left

17
Q

Tentorium cerebelli

A

lies between the posterior cerebral hemispheres and the cerebellum

18
Q

Diaphragm sellae

A

circular fold beneath the brain that covers the sella turcica.

19
Q

posterior fossa

A

the cavity formed with occipital bone as base and tentorium cerebella as roof.

Contains cerebellum and brainstem

20
Q

tentorial notch

A

hole within dural folds where the brainstem can go through

21
Q

Flow of CSF

A

lateral ventricles — foramen of Monro–> third ventricle (diencephalon) – cerebral aqueduct (midbrain) –> 4th ventricle in pons/medulla— foramen of Magendie and Luschka –> subarachnoid space around brian and spinal cord —> arachnoid granulations —> veinous sinuses

22
Q

Blood - CSF barrier

A

choroidal capillaries are fenestrated with no tight junctions BUT choroid epithelium (ependymal cells w/tight junctions) has the tight junctions. Therefore the choroid epithelium form the blood-CSF barrier

23
Q

hydrocephales

A

increase volume of CSF

  1. overproduction (rare)
  2. Obstruction of flow
  3. decrease reabsorption via arachnoid granules

May be chronic in children

24
Q

Communicating hydrocephalus

A

blockage of CSF reabsorption in arachnoid granules OR obstruction of flow in the subarachnoid space

25
Q

Noncommunicating hydrocephalus

A

obstruction of flow within ventricular system

26
Q

Symptoms of increased intracranial pressure

A
  1. headache
  2. Nausea and vomitting
  3. 6th Nerve palsy
    • eyes appear to look downwards
  4. papilledema (swelling of optic papilla)
  5. Decreased vision/ diplopia (double vision)
  6. Decreased cognition
  7. Unsteady gait
  8. Cushing’s triad: hypertension, bradycardia, and irregular respirations (brainstem)
27
Q

Blood brain barrier

A

formed by tight junctions of epithelium on capillary. The BBB may be disrupted by infections, tumor or trauma and can cause “vasogenic edema”
- shows up as breakdown of epithelium.

28
Q

Circumventricular organs

A

parts in which the BBB is interrupted. It enables the brain to resound to changes in the blood chemistry

  • Area postrema: detecting circulating toxins that cause vomiting
29
Q

Epidural Hematoma

A

Potential space

caused by trauma (fracture of the temporal bone) that lesions middle meningeal artery.

Rapidly expanding hemorrhage
Lens- biconvex shape

Increase in pressure causes a herniation

30
Q

Subdural hematoma

A

Potential space

rupture of bridging veins due to a high velocity impact. (acute)

Can be a chronic condition in elderly (brain shrinks which puts them at an increased risk of tearing a bridging vein.

Cresent shape

31
Q

Subarachnoid hematoma

A

Real space – has blood vessels

  1. Non-traumatic
    • WORST HEADACHE OF MY LIFE
    • aneurysms or Arteriovenus malformations
  2. Traumatic
    • bleeding into CSF from damaged blood vessels associated with cerebral contusions and other traumatic brain injuries
32
Q

What are the two types of Aneurysms?

A
  1. Saccular/ Berry:
    • balloon like
  2. Fusiform
    -main vessel itself becomes dilated (less likely to rupture and thereofer more likely to compress something)
    • Posterior communicating arter –> 3rd Nerve
      palsy
33
Q

where do aneurysms mostly occur? (Saccular)

A
  1. Anterior communicating artery (30%)
  2. Posterior communicating artery (25%)
  3. Middle cerebral artery (20%)
  4. Posterior circulation (15%)
34
Q

Transtentonial Herniation and symptoms

A

Uncal herniation – medial temporal lobe herniates through tenurial notch.

  1. blown pupil – ipsilateral dilated, unresponsive pupil (CN 3)
  2. Hemiplegia: paralysis of half of the body
  3. coma
  4. posterior cerebral arteries may be compressed – infarction in posterior cerebral artery territory.
35
Q

Central herniation

A

central downward displacement of the brainstem.

Mild herniation = traction on abducen’s nerve = lateral rectus (unilateral or bilateral)

36
Q

Tonsillar herniation

A

Cerebellar tonsils move downward through foramen magnum.

  • compression of medulla
  • leads to respiratory arrest, blood pressure instability and death
37
Q

Subfalcine herniation

A

unilateral mass lesions that cause cingulate gyrus (and other structures) to herniate under the flax cerebra from one side of the cranium to the other.

  • may be symptomatic
  • may have symptoms of increased cranial pressure