Blood Supply to the Central Nervous System Flashcards
What percentage of cardiac output goes to the brain?
10-20%
What percentage of liver glucose does the brain use?
66%
State the two main sources of blood supply to the brain?
Vertebral arteries (posteriorly) Internal carotid arteries (anteriorly)
State the major artery that the vertebral arteries branch off and describe the path of the vertebral arteries to the brain.
Subclavian artery The vertebral arteries pass through the transverse foramina of the cervical vertebrae and through the foramen magnum into the brain
Draw the circle of Willis.
DO NOT FORGET the superior cerebellar artery and the anterior inferior cerebellar arteries
State the names of the venous sinuses that are at the top and bottom of the falx cerebri.
Superior sagittal sinus Inferior sagittal sinus
What is the name given to the place where all the sinuses meet?
Confluence of sinuses
What connects the inferior sagittal sinus to the confluence of sinuses?
Straight sinus
What vessel does the inferior sagittal sinus join with to form thestraight sinus?
Great cerebral vein
Which sinus ascends to join the confluence of sinuses?
Occipital sinus
Which two sinuses run along the temporal bone?
Superior petrosal sinus Inferior petrosal sinus
Which main sinus drains into the internal jugular vein through the jugular foramen?
Sigmoid sinus
Which sinus connects the confluence of sinuses to the sigmoid and superior petrosal sinuses?
Transverse sinus
Which sinus runs along the sphenoid and parietal bones?
Sphenoparietal sinus- it comes off the cavernous sinus
Which sinuses run on either side of the pituitary stalk?
Anterior and posterior intercavernous sinuses
Which extension of dura mater separates the cerebellum from the inferior portion of the occipital lobe?
Tentorium cerebelli
Define Stroke.
a rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration
2 types: Infarction (85%) or haemorrhage(15%)
Focal =localised
Define Transient Ischaemic Attack (TIA).
A rapidly developing focal disturbance of brain function of presumedvascular origin that resolves completely within 24 hours
What percentage of strokes are caused by infarction and what percentage are caused by haemorrhage?
85% infarction 15% haemorrhage
State two causes of occlusions.
Thrombosis
formation of a blood clot (thrombus)
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Embolism
plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or atherosclerotic debris from the internal carotid
Describe the perfusion fields of the brain.
The anterior cerebral artery supplies the medial part of both hemispheres
The middle cerebral artery extends laterally and emerges through the lateral fissure between the frontal and temporal lobes – it supplies the front 2/3 of the lateral part of the hemisphere
The posterior cerebral artery supplies the medial and lateral parts of the posterior part of the hemisphere
slide 20
Describe the location of the leg in the motor and sensory homunculus compared to the arm.
Leg is more MEDIAL
Describe the features of a disturbance in the anterior cerebral artery.
Contralateral hemiplegia in the LEG more than the arm
Disturbance of intellect, executive function and judgement(abulia)
Loss of appropriate social behavior
The above 2 bullet points are functions of frontal lobe too
Describe the features of a disturbance in the middle cerebral artery.
“Classic stroke” - affects the lateral parts of the primary motor and somatosensory cortices.
Contralateral hemiplegia (paralysis of one side): affects arm more than leg (look at motor humunculus)
Contralateral hemisensory deficits (this artery supplies part of the somatosensory cortex too)
Hemianopia (loss of half of visual field)
Aphasia- speech problem (if it is a L sided lesion, Brocasarea is on the left hemisphere)
