ANATOMY - CSF Flashcards

1
Q

How much cerebrospinal fluid does the body produce per day? (½)

A

500ml

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2
Q

Discuss the production and circulation of CSF & comment on what the probable mechanism of this patient’s communicating hydrocephalus is (9)

A

CSF is produced by the choroid plexus (½) in the 2x lateral (½), third (½) and fourth ventricles (½). The CSF circulates in the lateral ventricles (½) then pass through the intraventricular formainae of Monroe (½) into the third ventricle (½). From there CSF drains into the fourth ventricle (½) by the cerebral/midbrain aqueduct of Sylvius (½). CSF drains from the fourth ventricle into the subarachnoid space (½) via the median aperture of Magendie (½) and the lateral apertures of Luschka (½). Once in the subarachnoid space, the CSF circulates through the cisterns (½), and is eventually reabsorbed by the arachnoid villi (½) which project into the dural venous sinuses (½). In the case of subdural empyema, exudate obstructs the arachoid villi (½) which prevents reabsorption of CSF (½) and consequent increase in intracranial pressure (½)

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3
Q

By use of a flow chart or annotated diagram, illustrate the circulation of CSF from its production, to its reabsorption (10)/ Outline the production, flow and reabsorption of CSF (May make use of a diagram) (7)/ Describe the flow of CSF from the fourth ventricle to where CSF is reabsorbed into the venous system. Include the names and positions of the cisterns. You may use a well labelled diagram as your answer (10)

A

Flow (5), Cisterns (5)

Choroid plexus in ventricles I, II, III, IV – production.

Flow – interventricular foramina – III to aqueduct in mesencephalon – IV – central canal of spinal cord; 1 median and 2 lateral apertures in posterior medullary velum – subarachnoid space – reabsorption by arachnoid villi into superior saggital sinus.

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4
Q

Draw a labelled flow diagram that shows the route of flow of CSF from its production through to its reabsorption (10)

A

Choroid plexus [arteries] in ventricles 1, 2 and 3; separate choroid plexus in ventricle 4. (2)
Ventricle I to 3 via interventricular foramen (1)
Ventricle 2 to 3 via interventricular foramen (1)
Ventricle 3 to 4 via aqueduct of midbrain (1)
Ventricle 4 to central canal of spinal cord (1)
Through 3 foraminae in roof of ventricle 4 to subarachnoid space (2)
Reabsorption of CSF via arachnoid granulations into superior sagittal [venous] sinus (2)

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5
Q

Using a short summary or flow diagram, describe the cisterns, their function and their locations within the neurocranium (11)

A

Dilation of subarachnoid space.

Allows for extra space between brain structures and bony elements of the skull base.

Cerebellomedullary cistern (Cisterna magna): between the cerebellum and the medulla.obl.

Pontine cistern (Prepontine cistern or cisterna pontis): surrounds the ventral aspect of the pons.

Interpeduncular cistern (Cisterna interpeduncularis): situated between the two cerebral peduncles.

Superior cistern (Quadrigeminal cistern or cistern of the great cerebral vein): situated dorsal to the midbrain

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6
Q

Patient with meningism. Neuroimaging reveals communicating hydrocephalus secondary to a subdural empyema.

Give a definition of hydrocephalus (1)

A

Excessive accumulation of CSF in the ventricular system

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7
Q

Differentiate between what is meant by communicating and non-communicating hydrocephalus (1)

A

Whether CSF can enter subarachnoid space from ventricle IV (mainly)

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8
Q

Describe the causes of hydrocephalus in an infant/child with a neural tube defect (9)

A

In the majority of cases, hydrocephalus is caused by the obstruction of the foramina opening the fourth ventricle to the subarachnoid space. A major cause of outlet obstruction in infancy is the Arnold-Chiari malformation, in which the cerebellum is partly extruded into the vertebral canal during foetal life because the posterior cranial fossa is underdeveloped. The condition is nearly always associated with spina bifida (5)

In the case of a NTD that is a meningomyelocoele, the neural elements may be tethered within the cyst, and unequal growth in length of the neural tube (spinal cord) and vertebral column cause traction on the brain stem, causing coning of the cerebellum and obstruction of the foramina in the roof of the fourth ventricle (4)

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