M1: Arterial Circulatory Sys Flashcards
describe the tunica intima
inner most layer of a vessel
made of endothelial cells and c-tissue
describe the tunica media
middle layer
made of smooth muscles arranged circularly around the vessel
thickest layer
describe the tunica adventicia
outer layer
made of c-tissue, nerve fibers and vasa vasorum (network of small vessels that supply the walls of vessels)
in contact w/ surrounding tissue
what are the 3 classifications of arteries based on size
arterioles
small and medium arteries
large, elastic arteries
describe arterioles
what controls their resistance levels
the primary point of resistance to blood flow
smooth muscle controls resistance and vessel contraction
describe sm and med. arteries
all arteries except the AO and its largest branches…
they have a well developed smooth muscle layer, and are more elastic and fibrous than arterioles
describe large arteries
includes the AO and its largest branches
larger amounts of elastic fibers and less smooth muscle
the brain is directly supplied by which 4 vessels
2 internal carotids
2 vertebral arteries
which vessels supply the central nervous sys
the great vessels off the AO:
brachiocephalic/innominate
Left CCA
Left subclavian
what are the branches of the innominate artery
right CCA
right subclavian
whats the best way to tel the ECA from the ICA when scanning
ECA has branches extracranially and the ICD doesn’t
when the L CCA branches from the AO arch, which joint does it pass under
L sternoclavicular joint
does the CCA have any branches
no
Anatomically, where does the CCA branch into the ICA and ECA
upper border of the thyroid cartilage
the ICA supplies the majority of which circulation in the brain
anterior circulation
does the ICA have any branches extracranially
no
first branch off the ICA
where does this branch occur
ophthalmic artery, occurs at the carotid siphon
intrecranially, the ICA bifurcates into which vessels
Middle cerebral artery (MCA) and anterior cerebral artery (ACA)
what is the carotid siphon
an intercranial, tortuous area of the cervical ICA that is divided into 3 segments
3 segments on the carotid siphon
inferior to superior:
parasellar - proximal curve
genu - bend
supraclinoid - distal curve
another name for carotid siphon
cavernous ICA
which part of the cavernous ICA does the ophthalmic artery branch from
genu
what are the 3 branches of the ophthalmic artery
supraorbital artery - most lateral branch
frontal artery
nasal artery - most medial branch ending near the bridge of the nose
the branches of the ophthalmic artery all communicate w/ branches of which artery
ECA
does the ECA usually supply blood to the brain
no
when may the ECA supply blood to the brain, how would this work
if there’s an occlusion in the ICA
branches of the ECA may anastamose w/ the ICA or vertebral arteries to provide collateral flow
what will happen to flow in the ophthalmic artery if the ECA is being used to supply blood to the brain
flow in the ophthalmic artery will be reversed and will instead be used to feed the brain
whats the first extracranial branch off the ECA thats often seen when doing carotid exams
superior thyroid
what is the typical location of the ECa in the neck
Anterior and medial to the ICA
Which branches of the ECA are the most important in the case of collateral circulation
Those branches in communication w/ the ophthalmic artery
Which branches of the ECA are important in the case of collateral circulation
Those branches in communication w/ the ophthalmic artery (MOST IMPORTANT)
The branches that interconnect b/w the muscular branches of the occipital and vertebral arteries
The vertebral arteries supply blood to which ‘circulation’ of the brain
Posterior circulation
Describe the location of the vertebral arteries
How do they travel in the body
Lie in the transverse foramina of the upper cervical vertebrae
Cephalad and anterior
Which artery do the vertebral arteries join to form in the head
Basilar artery
The Basilar artery has how many branches and what do they supply
4
Pons and cerebellum
Which arteries form the circle of Willis and where is it located in the brain
Confluence of the cerebral branches of the ICAs and the vertebral arteries
Base of brain
Which structure is the most important part of intracranial collateral circulation
Why?
Circle of Willis
B/c it connects the anterior and posterior circulation of the brain when needed
Which arterial vessels in the brain are a common site of aneurysm formation
Circle of Willis
The circle of Willis is formed by which arteries
Anterior, middle and posterior cerebral arteries, joined by ant and pos communicating arteries
Under norm conditions, is flow detectable in the ant and pos communi arteries
No
Which artery in the circle of willis supplies the majority of blood to the cerebral hemispheres
MCA
Which variation of the C of W is the most common
Absence of hypoplasia of 1 or more of the communicating artery’s
Approximately what % of the population has a norm C of W
25%
How many different configurations of the C ofW are there
9
In the extremities at rest, can total blood flow be norm in the presence of severe stenosis/occlusion
Yes, due to collaterals
4 ways obstruction of an artery can alter flow in collateral pathways
Increased volume
Increased velocity
Reversing flow
Altering pulsatility
Can locating collaterals help detect the level of obstruction
Yes
What is the most common variant of the upper extremity arterial system
What are 2 other variants
Common origin of brachiocephalic and L CCA of the AO arch
High origin of radial artery
Duplicated brachial artery
Is stenosis common for arteries is the upper extremities
No
What is the most common variant of the lower extremity arterial system
What is 1 other variant
Hypoplasia/aplasia of the anterior tibial artery
Anomalous location of the dorsal is pedis artery
Collateral routes for a distal AO and bilateral CIA obstruction
Thoracic and abdo wall arteries
Mesenteric arteries
Lumbar arteries
Collateral routes for unilateral CIA obstruction
What is the most common
Contralateral iliac or FA collaterals via pelvic arteries
Hypogastric
Collateral routes for EIA and CFA obstruction
Ipsilateral pelvic and femoral artery branches
Collateral routes for deep FA obstruction
Prox ipsilateral Pelvic and Sfs
Distal SFA pop artery
Collateral routes for SFA and pop artery obstruction
Deep femoral branches
Pop to tibioperoneal trunk
Collaterals for tibioperoneal trunk obstruction
Prox calf branches
Distal peroneal branches to ATA and PTA
Review anatomy from notes
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