Neuro 4 - 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
Internal carotid arteries
State the major artery that the vertebral arteries branch off.
Subclavian Artery
Vertebral arteries pass through the transverse foramina of the cervical vertebrae and through the foramen magnum
State the name of 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 the straight 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 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.
rapidly developing focal disturbance of brain function of presumed vascular origin that lasts more than 24 hours
Define transiet ischaemic attack.
a rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
What percentage of strokes are caused by infarction and haemorrhage?
infarction: 85%
haemorrhage: 15%
State two causes of occlusions.
Thrombus
Embolism
What is the difference between a thrombus and an embolism?
Thrombus - formation of a blood clot
Embolism - plugging of small vessel by material carried from a larger vessel
Describe the perfusion fields of the brain.
Anterior cerebral artery supplies the medial part of both hemispheres
middle cerebral artery extends laterally and emerges from the lateral fissure
supplies front 2/3 of the lateral part of hemisphere
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 leg more than arm
disturbance of intellect and executive function
loss of appropriate behaviour
Describe the features of a disturbance in the middle cerebral artery.
Classic stroke Contralateral hemiplegia in arm ARM more than the leg contralateral hemisensory deficits Hemianopia Aphasia
Describe the features of a disturbance in the posterior cerebral artery.
supplies occipital lobe
causes visual defects such as homonymous hemianopia and visual agnosia
Which parts of the brain are involved in speech and understanding language?
Broca - speech
wernicks - understanding language
What are lacunar infarcts?
small spaces in brain due to small vessel occlusion
caused by hypertension
State 4 types of hemorrhagic stroke and their likely causes.
Extradural - rapid - trauma
Subdural - slow - trauma
Subarachnoid - ruptured aneurysms
Intracerebral - spontaneous rupture of vessels
What is the difference between the dura on the vertebral column compared to the brain?
dura in vertebral column has 1 layer whereas dura in skull as 2
What are the two layers of dura in the skull called?
Periosteal and meningeal
What is the name given to the fold of dura that extends between the medial surfaces of the two hemispheres?
Falx cerebri
Why are extradural haemorrhages more rapid onset than subdural haemorrhages?
extradural are caused by rupture of a meningeal artery which is more high pressure
subdural = meningeal vein - low pressure
