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202 retake: theme 1 > L12. Ventricular system (AD) > Flashcards

L12. Ventricular system (AD) Flashcards

1
Q

give an overview of the ventricular system

A
  • Series of CSF-filled interconnected spaces

- Continuous with the subarachnoid space and central canal

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2
Q

how do the ventricles develop (embryonic stage )

A
  • Neuroectoderm forms neural tube
  • Lumen of neural tube becomes ventricles and central canal
  • Ependymal layer lines ventricles and central canal
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3
Q

describe the lateral ventricles

A
  • Two ventricles – Very large

One for each cerebral hemisphere

Body, anterior, posterior and inferior horn
corresponding to lobes of the hemisphere

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4
Q

look at labelling for lateral ventricles in slide 6

A

how was it

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5
Q

what are the borders of the lateral ventricles

A
  • Septum pellucidum separates lateral ventricles
  • Corpus callosum sits in roof
  • Caudate nucleus sits in lateral wall
  • Hippocampus sits in floor of inferior horn

slide 9

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6
Q

describe the interventricular foramen

A

Lateral ventricles communicate with the third ventricle through the interventricular foramen

  • Also called Foramen of Monro
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7
Q

describe the third ventricle

A
  • cleft between thalami

- fornix forms roof

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8
Q

study slide 12

A

how was it

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9
Q

describe the cerebral aqueduct

A
  • Third ventricle communicates with fourth ventricle through the cerebral aqueduct
  • Also called Aqueduct of Sylvius

– Surrounded by the midbrain

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10
Q

describe the 4th ventricle

A

Surrounded by hindbrain:

  • Cerebellum posterior
  • Pons and medulla anterior
  • Cerebellar peduncles lateral

Characteristic rhomboid shape (coronal view)

Continuous with the central canal of the spinal cord and subarachnoid space

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11
Q

describe 4th ventricle communication

A

Three foramen exit into subarachnoid space:

  • Two Foramen of Luschka (lateral)
  • One Foramen of Magendie (middle)
    - Into Cisterna Magna
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12
Q

study slide 17

A

how was it

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13
Q

describe the choroid plexus

A

CSF produced by choroid plexus

Filters blood from branches of internal carotid and basilar arteries

Choroid plexus present throughout ventricles:

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14
Q

describe the structure of the choroid plexus

A

Very simple

Capillary network surrounded by cuboidal epithelium

During CSF production:

1. Blood filtered through fenestrated capillaries
2. Components transported through cuboidal epithelium into ventricles

3) Tight junctions between epithelial cells
- Prevent macromolecules from entering CSF
- Permeable to water and CO2

4)- Forms blood-CSF barrier

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15
Q

study slide 20

A

how was it

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16
Q

describe the cuboidal epithelium

A

Specialized ependyma

Villi present to increase surface area

Active transport of CSF components

Bidirectional (uptake of metabolites into circulatory system)

17
Q

give the estimate % of CSF production in the head

A

60% CSF produced in ventricles

40% CSF from other sites within brain
18
Q

what is the CSF composition ideal for

A

physiological functioning of neurons

19
Q

what are the differences in protein composition between CSF and Plasma

A

CSF- 0.18g/l

Plasma- 75g/l

Differences due to regulation by active transport

20
Q

describe the route of CSF circulation

A

Lateral ventricles
(Interventricular foramen)

Third ventricle
(Cerebral aqueduct
)

Fourth ventricle
(Luschka and Magendie
foramina)

Cisterna magna
(subarachnoid space)

CSF passes out of ventricles into the subarachnoid space

then up spinal
subarachnoid space

Over cerebral hemispheres

(including arachnoid granulations & superior sagittal sinus)

then down dorsal spinal subarachnoid space

(central canal usually blocked in adults)

slides 23-24

21
Q

describe the subarachnoid space

A

Lies between pia and arachnoid

Subarachnoid space follows contours of brain

Functionally important: CSF in contact with brain parenchyma

				- transfer of micronutrients into brain 
				- removal of metabolites
22
Q

describe the arachnoid granulations

A

Herniations of arachnoid membrane (villi) through dura mater into venous sinuses

Mainly within the superior sagittal and transverse sinuses

23
Q

describe the absorption of CSF

A

CSF pressure must exceed that in venous sinuses

  • 150mm water in subarachnoid space
  • 80mm water in venous sinuses

If venous pressure exceeds CSF pressure:
- Tips of villi close off
(Prevents reflux of blood into subarachnoid space)

		Arachnoid villi act as one-way valves
24
Q

describe CSF volume and its factors

A

500ml CSF produced per day (0.35ml/min)

Total volume in system = 90-140ml
- Normally quoted 140ml
30 ml ventricles
110ml subarachnoid space

Continuously moving

Excess absorbed by arachnoid granulations

25
Q

what is the main functions of CSF

A

Hydraulic buffer to cushion brain against trauma

  1. Vehicle for removal of metabolites from CNS
  2. Stable ionic environment for neuronal function
    (communicates with brain interstitial fluid via pia)
  3. Transport of neurotransmitters and chemicals
26
Q

describe the different colours of CSF in disease

A

CSF normally clear sterile fluid

Discoloured in some pathological states:

Yellow (Xanthocromia)

E.g. Subarachnoid haemorrhage
- Lysis of red blood cells, haemoglobin release

Cloudy

E.g. Multiple sclerosis
- Protein content (gamma globulin) increase

E.g. Bacterial meningitis
- Leukocytes are increased, indicative of infection

27
Q

how is CSF sampled

A

Taken by lumbar puncture

At lumbar cistern
- No spinal cord

28
Q

describe the condition hydrocephalus

A

Dilation of brain ventricles

Due to blocked CSF circulation, impaired absorption, or over secretion

Increased intracranial pressure

Pressure on surrounding tissues affects neurological function

Can be congenital or acquired

29
Q

what are the symptoms of hydrocephalus

A

– Symptoms include: headaches, vomiting, visual disturbances, papilledema (swelling of optic disc), seizures, altered cognition, balance and coordination problems

30
Q

describe non-communicating hydrocephalus

A

Blockage within the ventricular system
- Due to tumour, cyst, stenosis (e.g. narrowing of cerebral aqueduct)

CSF does not circulate over surface of brain

Surgery: Insert shunt to reduce intracranial pressure

31
Q

describe Dandy-walker syndrome

A

Congenital malformation of the cerebellum (1:30,000 births)

Obstruction within foramina of fourth ventricle:
-Symmetrical dilation of lateral, third and fourth ventricles

In infancy, child’s head may become enlarged:

32
Q

describe communicating hydrocephalus

A

Obstruction in the arachnoid villi

Movement of CSF into venous sinuses is impeded

  • E.g. Impaired absorption following subarachnoid haemorrhage, trauma or bacterial meningitis

202 retake: theme 1 (21 decks)

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