Blood Supply V2

Purpose of blood in the brain

to provide oxygen and nutrients to the brain and to drain CO2 and waste 

Why is the  brain vunerable to artial disruptions

due to constant need for oxygen and glucose 

Two blood supply chains to the brain 

Vertrebal and Carotid

17% of the population has this on their carotid artery 

unilateral carotid, typically carotid arteries are on both sides 

common carotid artery origin

brachiocephalic artery on the right and arch of the aorta from the left

how does the common carotid artery ascend 

ascends parallel to the jugular vein and vagus nerve and continues until about C6

Where does the carotid artery split

At C6 into external and internal

External purpose

supplies neck and face with blood 

First branch of internal 

Turns S shape and branches to opthalmic artery 

Opthalmic artery purpose 

travels in orbit with optic nerve II to provide blood to orbit, forehead, and small branches of the nose

Opthalmic artery branch

it branches off further into central retinal artery 

purpose and clinical indications of central retinal artery 

supply retina with blood, can be observed to see quality of opthalmic branch

Opthalmic artery clinical indications

may be surgically connected to facial artery/ superficial temporal artery (all forms of external carotid arteries) to provide blood flow if internal carotid artery becomes restricted-> only done with slow blockages and not clots

Carotid artery after opthalmic branch 

splits off into its terminal branches- anterior cerebral and middle cerebral 

Anterior cerebral artery pathway 

passes trhough corpus collosum (connection between two hemispheres)

Anterior cerebral artery function

supplies frontal ipsilateral cerebral hemisphere

What happens if one anterior cerebral artery fails?

the anterioir communicating branch connects them, thus the contralateral side can provide blood if needed 

Middle cerebral artery placement and function

on lateral surface of the brain and supplies ipsilateral temporal, parietal, and the outer portion of the frontal lobe

What two branches does the middle cerebral split into 

posterior communicating and lenticulostraite 

lenticulostraite 

provides deep brain supply to internal structures such as the basal ganglia, comes from middle cerebral

posterior communicating 

connects to vertebral system- branches from middle cerebral 

Vertebral artery origin 

begins from subclavian artery and ascends up to the neck by passing trhough transverse foramina before medially crossing over arch of atlas before entering cranially through foramen magnum 

1st branch of vertebral artery 

posterioir cerebellar artery 

purpose of posterior inferior cerebellar artery 

supplies blood to the posterior inferioir cerebellum 

what does posterioir inferioir cerebellar branch branch off to 

anterioir spinal cord artery 

How is the basilar artery formed 

after the posterior inferior branch branches off, the other side of the vertebral artery joins to create the basliar artery 

WHere does the basilar artery supply to 

anterior inferior cerebellum, labrynithe arteries, and pontine series 

What do the basliar arteries split off to

superioir cerebellar arteries 

what does the superior cerebellar arteries split and terminate

posterior cerebral arteries 

Where does the oculomotor nerve pass

in between the superioir cerebellar and the inferior cerebral arteries 

where does the posterior cerebral arteries supply

occipital and connects with the carotids posterior communicating 

What does the circle of willis entrap 

pituitary glands, mamillary bodies, and the optic nerve

65% of the population has this with their carotid artery

right and left do not originate equally: has 3 seperate vessels come off at the aortic arch: brachiocephalic, left common, and left subclavian

anterioir system source

carotid

posterioir system source

vertebral artery

where is the carotid bifurcation 

C6

35% of the population has this..

left common and braciocephalic share a starting point and left subclavian (2 branches instead of 3) 

Why is left sided stroke even more common for a bovine anatomy

since the left carotid shares a barchiocephalic origin, there are now only 2 points of access: now its more likely for a bloackage to occur in the subclavian since now theres only 2 routes to go to

Which artery provides a safety redundancy 

the ACA- anterior cerebral artery- left and right join at anteriori communicating branch thus creating a safety redunancy 

the vetrebral system originates from…

subclavian artery 

where does the posterior cerebral artery supply to 

supplies to occipital lobe

How do berry aneurysms occur

posterioir cerebral artery and superior cerebellar artery impinge on the 3rd CN (oculomotor) 

How do berry aneurysms present

inability for eyes to turned outwards, diplopia (double vision), droopy (ptosis), dialated pupil (mydriasis), difficulty focusing on close up objects

cerebral ischemia

incomplete or diseased circle of willis are less effective at compensating for blockages in other cerebral arteries, thus increasing the risk of ischemic stroke 

hemorrhagic stroke

atherosclerotic (thickening of arteries) changes and weakening Circle of willis will increase risk of aneurysmal rupture and subsequent hemorrhagic stroke 

neurodenegerative disease 

atherosclerosis in circle of willis-> AD&nbsp