brain blood vessels - blood supply to the CNS & intracerebral bleeds Flashcards
what 2 paired arteries are responsible for blood supply to the brain?
-vertebral artery
-internal carotid arteries
which artery is the vertebral artery a branch of?
the subclavian artery
what artery is the internal carotid artery a branch of?
- branch of common carotid artery
what do the terminal branches of these 2 paired arteries form in the brain?
terminal branches of these arteries form an anastomotic circle, called the Circle of Willis
at what vertebral level does the common carotid artery bifurcate?
C4
through which ‘canal’ does the ICA ascend into the brain?
- carotid canal
once the ICA has entered the cranial cavity, what structure does it pass through?
passes through the cavernous sinus anteriorly
what are the branches of the ICA?
-ophthalamic artery
-anterior choroidal artery
-posterior communicating artery
-2 terminal branches : anterior and middle cerebral artery
what does the ophthalmic artery supply?
supplies structures of the orbit
what does the anterior choroidal artery supply?
supplies structures in the brain important for motor control and vision.
-also supplies optic chiasma, optic tract, lateral geniculate etc
what’s the function of the posterior communicating artery ?
acts as an anastomotic ‘connecting vessel’ in the Circle of Willis
where do the arteries lie within the 3 layers of the meninges?
the subarachnoid space
what are the branches of the vertebral artery?
-PICA - posterior inferior cerebellar artery
-anterior spinal arteries
-posterior spinal arteries
-meningeal branch
what does the meningeal branch of the vertebral artery supply?
falx cerebelli, a sheet of dura mater.
what do the anterior and posterior spinal arteries supply?
supplies the spinal cord, spanning its entire length.
what does the PICA artery supply?
the cerebellum
once the vertebral arteries branch out, what do they do?
the two vertebral arteries converge to form the basilar artery
through what foramen does the vertebral arteries ascend into the cranial cavity ?
foramen magnum
what does the basilar artery supply?
-posterior circulation of brain
-goes along the midline of the pons
what are the branches of the basilar artery? ALPS
-AICA - anterior inferior cerebellar arteries
-labryrinthine arteries
-pontine arteries
-superior cerebellar arteries
what is the circle of willis?
a circle - in which the internal carotid artery and vertebral arteries anastomose and communicate with each other
what are the 3 main paired arteries of the circle of willis?
-Anterior cerebral arteries – terminal branches of the internal carotid arteries.
-Internal carotid arteries – located immediately proximal to the origin of the middle cerebral arteries.
-Posterior cerebral arteries – terminal branches of the basilar artery
what are the 2 connecting vessels in the circle of willis?
-Anterior communicating artery – connects the two anterior cerebral arteries.
-Posterior communicating artery – branch of the internal carotid, this artery connects the ICA to the posterior cerebral artery.
what are the 3 cerebral arteries?
-anterior
-middle
-posterior
what part of the CNS does the anterior cerebral artery supply?
-orbital surface of frontal lobe
-medial aspect of hemisphere
-upper border of frontal and parietal lobes
what part of the brain does the middle cerebral artery supply?
-lateral aspect of the cerebral hemisphere except occipital lobe
-thorax, upper limb, head and neck - speech & auditory
functionally, what areas of the body might a blockage of the anterior cerebral artery in a stroke affect?
-lower limb - sensory and motor loss
-perineum / pelvic area - micturition and defecation
functionally, what areas of the body / functions of body might be affected by a blockage of the middle cerebral artery?
-head and neck - speech and auditory function
-weakness and paralysis on the opposite side of the body
-numbness & loss of sensation on one side of the body
what do the medial striate arteries supply?
-internal capsule (important structure transmitting motor and sensory information between the cerebral cortex and the brainstem/spinal cord.)
-near the basal ganglia - head of caudate, medial globes pallidus etc
what do the lateral striate arteries supply?
-internal capsule
-basal ganglia - putamen
define stroke
sudden death of brain cells due to lack of oxygen, caused by the blockage of blood flow or rupture of an artery to the brain
what can cause ischaemia of brain cells?
-thrombosis (clot in one of the cerebral arteries)
-embolism (generated in vessel outside of brain eg carotid artery)
-hypertension
-rupture of blood vessels
-trauma
-aneursym
what symptoms would occur in a cerebral hemisphere stroke - compare anterior cerebral vs middle cerebral?
-anterior cerebral - contralateral hemiplegia & anaesthesia - lower limb (paralysis affecting 1 part of body)
-middle cerebral - contralateral hemiplegia and anaesthesia - upper limb & thorax - also brocas or wernickes aphasia - damage to speech / auditory
what symptoms can occur with posterior cerebral arterial stroke?
contralateral hemianopia (loss of 1/2 of visual field)
what are signs of a cerebral hemisphere stroke?
-ipsilateral symptoms - same side of body
-cerebellar signs eg loss of balance & co-ordination
what is lateral medullary syndrome / PICA?
-syndrome caused by damage to the lateral part of the medulla oblongata
-symptoms eg ipsilateral pain and temp loss from face (trigeminal nucleus)
-vertigo, tinnitus - vestibulocochlear nuclei
-ipsilateral horners syndrome
what is medial medullary syndrome?
neurological condition caused by damage or infarction of the medial part of the medulla oblongata in the brainstem.
what are examples of symptoms of medial medullary syndrome?
- contralateral hemiparesis - muscle weakness on 1 side
- contralateral loss of sensation eg fine touch
-ipsilateral paralysis of tongue
