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36 Cards in this Set

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  • Back
Name the structures
Name the structures
Name the structures
Name the structures
What is the percentage of epidural hematoma that is from a venous origin?
10%
When do you typically see an epidural hematoma?
blows to the side of the head that ruptures a middle meningeal artery
Most bleeds into the subarachnoid space are from?
aneurysms from the Circle of Willis
How would a stroke occur after a subarachnoid haemorrhage?
blood in the subarachnoid space mixes with the CSF and coats the pia. RBCs then die and release their contents which are vasoconstrictive and decrease arterial diameter which may lead to a stroke
Via which foramina does the 3rd ventricle communicate with the lateral ventricles
Foramina Munro
What is the name of the aqueduct that transverses the midbrain?
Mesencephalic (cerebral) aquaduct
Describe the structures around the 4th ventricle
Sandwiched between: cerebellum, pons and rostral medulla.

It's floor = rhomboid fossa

It's roof = superior and inferior medullary vela of the cerebellum
What are the three apertures in the 4th ventricle?
foramen of Magendie
foramina of Luschka
How does CSF differ from blood?
High in: Na, Mg

Little in: K, Ca

Low in: Cells and protein

Remains stable
Where is CSF made?
Choriod plexus (80%) and ependyma cells (line ventricles)
Where is the choriod plexus not found?
anterior and posterior horns of the lateral ventricles

Note: important for catheters or measuring pressure. Choriod plexus clogs catheter tip
How much CSF is made per day?
500ml
How many times is CSF replaced in a day?
4 times
Which Cistern contains he Circle of Willis?
Interpeduncular Cistern
Which Cistern is of radiological improtance and why?
Superior Cistern

Contains:
1. great cerebral vein of Galen
2. pineal gland
3. continues rostrally into transverse fissure
True of False:

When the pressure is high in the Subarachnoid space, it follows down it's concentration gradient into the dorsal venous sinuses (e.g. Superior Sagittal Sinus) and when the pressure is high in the sinuses, CSF flows back down its concentration gradient into the subarachonoid space
False

The flow is unidirectional, due to valves in the arachnoid villi
Where are the three main blood-brain-barriers?
1. Arachnoid
2. Choroid Plexus
3. Cerebral Capillaries
How does the arachnoid act as a BBB?
Passive functions

1. ependymal cells fold over themselves
2. tight junctions
3. impermeable to hydrophilic substances
How does the Choroid Plexus act as a BBB?
Selectively permeable -prevent most macromolecules from entering CSF

1. Microvilli on CSF side -allows CSF out
2. Tight junctions -keep most things from getting in

More permeable than the other BBBs
How does the Cerebral Capillaries act as a BBB?
1. Non fenestrated
2. Tight Junctions of endothelial cells
When might the BBB break down?
1. infection
2. Trauma
3. Stroke
4. Tumour
What type of Spina Bifida does the following features describe?

Defect in the lumbosacral region, where the SC, spinal roots and meningitis protrude into a sac/cysts and there is constant leakage of CSF
Spina bifida cystica -myelomeningocele
When does myelomeningocele usually occur in gestation and what is it due to?
Usually 4th week of gestation

Due to failure of posterior neuropore closure
When should folate supplement be given to a woman preparing to have a child and why?
before 3-4 weeks of gestation (before neural tube is programmed to close)

Reduces the risk of myelomeningocele by 80%
What are the reasons for a child born with myelomeningocele developing hydrocephalus?
1. abnormal part of the SC tethering to the vertebral column. Which pulls the medulla into the foramen magnum

2. CSF is escaping through the opened neural tube, however after surgery, hydrocephalus can occur due to the above mentioned reason
At what level does spina bifida occult usually occur?
the arch of a single vertebra is opened usually either at LV5 or SV1
When does spina bifida occult occur during gestation and why?
Occurs: 5-12 weeks of gestation

Why: failure of the vertebral precursor cells to migrate around the SC
True or False

Spina Bifida Occulta isn't associated with any clinical features because the SC is normal?
True

Only a defect of the vertebral column which is often marked hy a tuft of hair, pigmented nevus or a dimple
What is the only difference between Spina Bifida Occulta and Spina Bifida Cystica -meningocele?
Several vertebrae are involved in meningocele.

Meningocele is rare malformation
What is a common herniation?
Herniation across the temporal lobe/over tentorium cerebelli

Causes:
1. paresis of IIIn
2. contralateral UMN symptoms (due to compression of cerebral peduncle against tentorium)
What type of herniation is life threatening and why?
Tonsillar herniation

because it compresses vital centres in the BS --> coma