Blood supply to the Central nervous system Flashcards
LO1 Arterial blood supply: Name the 2 sources of blood supply to the brain
- two internal carotid arteries (front)
- two vertebral arteries (back)
4 vessels come together to give rise to Circle of willis. Cerebral arteries come out of the circle.
LO 1 Identify perfusion fileds for the main cerebral arteries and explain neurological deficits that result following disruption
Circle of Willis. Label the diagram
diagram
Label the diagram of perfusion fields
- 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
- The anterior cerebral artery supplies the medial part of the hemisphere
- Posterior cerebral artery supplies the lateral and medial third
What are the results of the disturbance of the anterior cerebral artery
- Paralysis of the contralateral LEG more so than the arm
- This is because the motor homunculus shows that the part of the motor cortex that controls the leg is more medial to the part controlling the arm •
- Disturbance of intellect, executive function and judgement (abulia - absence of willpower)
- Loss of appropriate social behaviour
What are the results of the disturbance of the middle cerebral artery
- CLASSIC STROKE
- Contralateral hemiplegia - more the contralateral ARMS than the legs Because the lesion is more lateral - this is where the part of the motor cortex controlling the arms is found
- Contralateral hemisensory deficits
- Hemianopia
- Aphasia (Left sided) - can’t speak
- Left-sided lesion of the middle cerebral artery will result in aphasia because the language centres are more on the left side of the brain than the right
- NOTE: Broca’s Area - involved in speech Wernicke’s Area - involved in understanding language
What are the results of the disturbance of the posterior cerebral artery
Posterior cerebral artery supplies the occipital lobe where you find the primary visual cortex • This leads to visual defects: Homonymous hemianopia Visual agnosia (inability to recognise faces)
Describe the venous drainage of the brain.
- cerebral veins
- venous sinuses
- dura matter
- internal jugular vein
Define stroke and TIA
- Stroke=Cerebrospinal accident (CVA): Rapidly developing focal disturbance of brain function of presumed vascular origin lasting more than 24 hours infarction (85%) or haemorrhage (15%)
- Transient incident attack (TIA): Rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
List the main risk factors for stroke
Age Hypertension Cardiac disease Smoking Diabetes mellitus
Define:
- cerebral ischaemia
- cerebral infarction
- cerebral thrombosis
- cerebral embolism
- cerebral haemorhage
- cerebral ischaemia: Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly • Due to hypoxia/anoxia
- cerebral infarction: Degenerative changes that occur in tissue following occlusion of an artery
- cerebral thrombosis: formation of a blood clot (thrombus)
- cerebral embolism: plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or atherosclerotic debris from the internal carotid
- cerebral haemorhage
2 causes of occlusions: thrombosis and embolism
Distinguish between atheroma and infarction
diagram notes
LO15: Compare the effects of a cerebrovascular accident in the cerebral cortex with one in the brainstem
LO16: Which are the two types of haematoma and what causes them?
Give the possible consequences.
1) Extradural: meningeal artery rupture
2) Subdural : rupture of veins, Slower, effects delayed
What are lacunar infarcts
Lacune is a small cavity. appear in deep structures as a result of small vessel occlusion. deficit is dependent on anatomical location. hypertension can cause lacunar infarcts.
Meninges and superficial cerebral veins. Label the diagram
diagram
