Blood supply to the eye and the brain Flashcards
which blood vessel carries blood that has come from the body
vena cava
which blood vessel carries blood from the right ventricle to the lungs
the pulmonary artery
what are the parts of the aorta
ascending aorta
descending aorta
brachiphelic artery which has 3 branches right subclavian artery, right vertabral artery and right common carotid artery
what is the difference between the left common carotid and the right common carotid artery
the left common carotid artery and vertabral arery branches directly off the aortic arch
where do the vertabral arteries branch off
the vertabral arteries branch off the subclavian arteries on each side
i.e. left vertabral artery branches off the left subclavian artery and the right subclavian artery branches off the right vertabral artery
at what level does the common carotid artery split into two levels
bifurication of the common carotid arteries into internal and external occurs at the level of c4 of your cervical vertabrae - ( the neck area of your spine) (which lies around the superior margin of the thyroid cartilage)
their is a slight dilation at this point - this corresponds to the carotid sinus (baroreceptors involved in BP regulation are here)
what is the function of the external carotid artery
supplies areas of the head and neck external to the cranium
branches - some anatomists like freaking out poor medical students
superior thyroid artery
ascending pharyngeal artery
lingual artery
facial artery
occipital artery
posterior auricular artery
maxiallry artery
superficial temporal artery
what are the terminal branches of the external carotid artery
- the maxillary artery and the superficial temporal artery
what is the maxillary artery
- larger of the branches of the external carotid artery
supplies deep structures of the face
3 main portions
mandibular (1st part)
ptyergoid (2nd part )
ptergopaletine (3rd part)
what is the function of the superficial temporal and facial arteries
supply superficial facial arteries
what is the difference between the superficial temporal arteries and the maxilary artery
maxillary artery- supplies the deep structures in the face
as opposed to the superficial temporal arteries supply the superficial structures of the face
what is the function of the internal carotid artery
does not supply any neck structures- goes through the neck but dosnt have any branches in the neck itself
enters the cranial cavity via the carotid canal (which lies in the petrous temporal bone)
goes on to supply the : brain, eyes and forehead
through what foramen do the vertabral arteries travel through
transverse foramen
what is the internal carotid artery divided into
internal carotid artery is divided into segments c1- c7
one of the braches of your internal carotid artery is your opthalmic segment (c6)- it is from this segment that your opthalmic artery is going to come off-
where does your opthalmic artery come from
- the opthalmic artery comes off your internal carotid artery
where do your vertabral arteries come from
arise from the subclavian arteries
enter the cranial cavity via the foramen magnum
right and left vertabral arteries then join to form the basilar artery which goes on to supply the brain
describe the course of the vertabral arteries
you have right and left vertabral arteries which travel up the transverse foramen and enter the cranium via the foramen magnum and then it joins together to form the basilar artery which supplies the brain
what are the three main branches of the aorta
- the aortic arch gives rise to 3 main branches the brachiocephalic trunk , left common carotid and left subclavian
at what level does the common carotid artery bifurcate
- the common carotid artery bifurcates into the external and internal common carotid artery at the level of c4
what does the external common carotid artery supply
the external common carotid artery supplies the head and the neck structures
what are the two terminal branches off the eca
the maxillary artery and the superficial temporal
how does the ica enter the cranial cavity
the ica enters the cranial cavity through the carotid canal and supplies the brain , eyes and forehead
what do the vertabral arteries branch off
- the vertabral arteries branch off the subcalvian artery, enter the cranial cavity via the foramen magnum , and join to form the basilar artery which supplies the brain
what is the circle of wlillis
- anastomosis of arteries supplying the brain
comprimises the anterior cerebral arteries
anterior communicating arteries
internal carotid arteries
posterior cerebral arteries
posterior communicating artery
describe the structure of the circle of willis
- the vertabral arteries come off the subcalvian arteries - they join together to form the basilar artery- - the basilar artery then gives off the posterior cerebral arteries - between the posterior cerebral artery and the ica you have the posterior communicating artery - the ica then gives off the anterior cerebral artery - in between these two cerebral arteries ou have the anterior cerebral artery and then at the top you have the anterior communicating artery
where does your brains blood supply come from
right and left internal carotid
vertabral arteries
together feeds into the circle of willis which provides blood supply to the brain
what does the middle cerebral artery supply
the middle cerberal artery supplies most of the lateral surface of the hemisphere
what does the anterior cerbral artery supply
the anterior cerebral artery supplies the medial aspect of the frontal love
supreomedial parietal lobe and internal capsule
what does the posterior cerebral artery supply
midbrain and the thalamus
occipital lobe - ( visual cortex)
inferomedial temporal lobe
what is the circle of willis
the circle of willis is an arterial anastomosis supplying brain structures
how can the brains vascular territories be divided
the brains vascular terrorities can broadly be thought of in terms of anterior, middle and posterior cerebral arteries
what is the bamford classification og stroked
- the bamford classification is used for ischaemic strokes and describes 4 main types of ischameic strokes
TACS , PACS , LACS AND POCS
what are dural venous sinuses
- how your brain brings blood back towards the heart
- instead of having veins it has structures called venous sinuses - which lie between the endosteal and meingeal layers of your dura mater in the brain ( the brain has three layers dura mater, arachnoid mater and pia mater)
recieves blood from the cerebral veins and cerebrospinal fluid from the subarachnoid space
drains into internal jugular veins
what blood vessel supplies the eye and the orbit
- the opthalmic artery - which is a branch of the internal carotid artery- it is the first branch after it leaves the roof of the cavernous sinus
enters the orbit via the optic canal - below and lateral to the optic nerve
what are the branches of the opthalmic artery
- central retinal artery
- cillary arteries
- lacrimal arteries
- muscular branches
what is the function of the central retinal artery
supplies the inner 2/3 of the retina
what is the function of the cillary arteries
- you have 3 types
- long posterior cillary arteries - usually 2 pierce sclera and run forward to the cillary body , supply choroid, cillary body and iris
- short posterior cillary arteries- pierce sclera around entrance of the optic nerve, supply choroid , 15-20% cilioretinal artery
anterior cillary artery - supplies sclera and conjuctiva tendon insertions - they are branches of the muscular branches - which supply the recti muscles
in a substet of the population the cillary vasculature can sometimes have an abberration called the cilioretinal artery - useful if you have a blockage in your central retinal artery - because the cilioretinal artery can replace it
how does the retina recieve its blood supply
cillary arteries supply the retina
choroid supplies the outer 2/3 of the retina
inner 1/3rd via the central retinal artery
how is the blood retinal barrier formed
- zona occludents of the endotheliel cells of the cra capillaries
- zona occludentes between cell membranes in rpe
what does a central artery retinal occlusion look like
pale retina with a red cherry spot
- the fovea has a foveal depression- to allow as much light as possible to come through- the choroid is underneath
when you have a CRAO the outer 1/3 of the retina loses its blood supply and becomes pale
in the rest of the retina you can see that it is very pale but because the fovea is very thin you can see through to the choroid which is supplied by the cillary vessels and is therefore is perfused and you are seeing the chorioid which is why you have the cherry red spot
what is cilioretinal sparing
in people with a cilioretinal artery in a CRAO you get sparing in the area which is supplied by the central retinal artery - good for these patients - prevents blindness
what does the lacrimal artery supply
the lacrimal gland - gives off a branch called the lateral palpebral artery which supplies the lateral half of the upper eyelid
what do the muscular branches supply
- muscular branches go off to the recti muscles and anteriolly give off the anterior cillary arteries
what does the superior orbital artery supply
the superior orbital artery supplies the levator palpebrae superioris
what do the posterior and anterior ethmodial arteries supply
they go to the ethmoidal arteries and supply the sinuses and part of the upper nasal cartilage
how is the blood from the eye drained
venous drainage of the choroid is via vortex veins
- usually 4 vortex veins one for each quadrant
superior drain to superior opthalmic vein and inferior drain to the inferior opthalmic vein
( 2 superior and 2 inferior )
describe venous drainage of the opthalmic veins
superior opthalmic veins drain directly into the cavernous sinus
inferior opthalmic vein drains into the pterygoiud venous plexus
valveless system - oribital cellulitis/ facial infection can travel backwards into the cavernous sinus and percipitate cavernous sinus thrombosis
describe venous drainage of the central retinal vein
central retinal vein
drains inner retina
travels in the optic nerve
joins supeior opthalmic vein and therefore drain into cavernous sinus
how is the blood supplied to the eye
- arterial supply is via the opthalmic artery which branches off ica as the first branch after exiting the cavernous sinus
this gives off 11 different branches
what is the central retina artery responisble for
crao supplies the inner 2/3 of the retina but is an end artery and therefore vunreable to occlusion - crao
what is the function of the cillary artery
the cillary arteries (long posterior and short and anterior cillary) supply the outer 1/3 of the retina and anastomose within the choroid
what is the blood retinal barrier formed by
- sona occludentes of rpe and cra endothelium
what is venous drainage of the eye via
venous drainage is via vortex veins and the central retinal vein
which artery branches directly off the aortic arch
- left subclavian artery
describe the branches of the aorta
- brachiphelic artery which gives off your right subcalvian artery, right vertabral artery and right common carotid artery
- you have left common carotid artery
- your left subclavian and vertabral artery branch directly off your aortic arch
what are the terminal branches of the external carotid artery
- maxillary artery - supplies deep facial structures - and superfical temporal artery
what does the internal carotid artery give off
- the internal carotid artery gives off the opthalmic artery
what formaen does the internal carotid artery enter the cranial cavity through
enters the cranial cavity through the carotid canal
what part of the internal carotid artery gives off the opthalmic artery
- the opthalmic segment
where do the vertabral arteries arise from
the subclavian arteries
what do the vertabrak arteries ascend via in the cervical vertabrae
- vertabral arteries ascend via the transverse foramen
how do the vertabral arteries enter the cranial cavity
- formaen magnum
what do the vertabral arteries join to form what artery
basilar artery which go on to supply the brain
describe the circle of willis
- vertabral arteries , then bassilar artery , posterior cerebral artery
in between the posterior cerebral artery and the middle cerebral artery is the posterior communicating artery
at the end of the middle cerebral artery is the internal carotid artery
between the middle cerebral artery and the anterior cerebral artery is the anterior communicating artery
what artery is most likely to be involved in a total anterior circulation stroke
middle cerebral artery -
it supplies the frontal lobe the temporal lobe
supplies more in the brain than the anterior cerebral artery
which of the meningeal layers contains the dural venous sinuses
- the dura mater - the dura mater itself has two different layers , the meingeal and endosteal layers
where does the blood that drains through the dural venous sinuses come from
- they receive blood from the cerebral veins and cerebrospinal fluid from the subarachnoid
where do the dural venous sinuses drain into
- internal jugular veins
which artery supplies blood to the eye
- opthalmic artery - which is a branch of the internal carotid artery- first branch off the ica as it leaves the roof of the cavernous sinus
what does the central retinal artery supply
- the central retinal artery supplies the inner 2/3rds of the retina - the inner 2/3 has capillaries perfusing it - there are capillaries from the CRA perfusing the inner 2/3 of the retina- the outer 1/3 has no capillary network- relies on diffusion from the choroidal vessels
- the choroid (posterior cillary arteries) supply the outer 1/3 of the retina
what is the blood retinal barrier formed by
- the inner 2/3 of the retina has its blood supply from capillaries which come from the CRA - in order to control what comes into and out of the retina (this is what the blood retinal barrier does) you have meshworks of proteins which lies between the cells of the capillaries
- because the outer retina has no capillaries within it - it relies on diffusion - and this is from capillaries from the posterior cillary arteries which supply the choroid- choroidal diffusion supplies the outer 2/3 of the retina - in order to control what comes out of the outer 2/3 of the retina because their is no capillaries within here you have zona occludens between the retinal pigmented epithelium
how many vortex veins are there draining the choroid
- vortex veins drain the choroid
- there are usually 4 vortex veins draining the choroid - usually one for each quadrant
superior drain into the superior opthalmic vein and inferior drain into the inferior opthalmic vein
where do your superior opthalmic veins drain into
- cavernous sinus
where do your inferior opthalmic veins drain into
inferior opthalmic veins drain into ptergoid venous plexus
what does a fundus image look like in a CRAO
central retinal artery supplies the inner 2/3 of the retina and therefore it gives a reduced blood supply and a pale retina
- inner tissues have lost their blood supply- because cra has been blocked - becomes ischameic and pale which means you can see through to the choroid underneath
the red spot= the choroid
what does a fundus image of a central retinal vein blockage
tortuous blood vessels
- blockage of the central retinal vein - blocks the blood supply from flowing back out
