Quiz 3 Cerebrovascular Flashcards
Blood is supplied to the brain via 4 vessels:
Internal Carotid Arteries ( R & L)
Vertebral ( R & L)
T or F:
Of the extracranial cerebral arteries the right & left sides are generally not symmetrical
true
What comes off the right side of the aortic arch?
Brachiocephalic (innominate). Then divides into the CCA & subclavian.
What comes off the left side of the aortic arch?
CCA & subclavian arteries come directly off the aortic arch.
Common Carotid Artery
has no branches.
divides into internal & external carotid arteries.
At level of bifurcation, the carotid artery widens to form the carotid bulb.
Carotid sinus: widened area of proximal ICA. adjacent to ECA.
Carotid bulb ends at “flow divider” (bifurcation)
Internal Carotid Artery
Feeds the brain –> supplies it with oxygen.
Low resistance waveform.
No extracranial branches.
Within the skull, distal segment of ICA follows
a curved path – CAROTID SIPHON.
1st Intracranial Branch = ophthalmic artery
Intracranial Branches of the ICA:
1st Branch –> Ophthalmic Artery.
Anterior choroidal a.
Posterior communicating arteries.
ICA finally divides into the MCA & ACA.
ICA on ultrasound:
90% of the time the ICA is posterior & lateral to the ECA. ICA usually more: lateral posterior diseased. tortuosity common.
External Carotid Artery
supplies the facial structures with blood.
High resistance waveform.
ECA extracranial branches (2 most important)
Superior Thyroid - 1st branch
Superficial Temporal
The hole at the base of the skull is called the ________ & is easily visualized by US.
Foramen magnum.
Vertebral Arteries
Posterior circulation of the brain.
Join to form the basilar artery just inside the skull.
First branch of the subclavian artery.
The ______ VA is often larger than the ______ Vertebral artery.
left is often larger than the right.
Basilar artery divides to form the ________.
Posterior Cerebral Artery.
Circle of Willis
at base of brain, joins cerebral branches of ICA
Internal Jugular Veins
Right and left internal jugular veins pass lateral to ICA and CCA.
Unite with subclavian veins posterior to clavicles to form brachiocephalic veins.
Brachiocephalic veins then drain into SVC.
Drains brain, face and neck.
External Jugular Veins:
Begin at parotid gland near angle of mandible.
Superficial veins that descend inferiorly through SCM muscle.
Terminate mid clavicle, empty into subclavian veins.
Drains scalp, superficial & deep regions of face (External to cranium.)
The left common carotid originates at the :
aortic arch.
The right common carotid originates from the
innominate artery
The first branch off of the subclavian artery is the
vertebral artery
The ICA is usually more
posterolateral
The external jugular veins drain into the:
subclavian veins
The first extracranial branch of the ECA is the:
Superior Thyroid
The “Curly” part of the intracranial ICA is termed the:
Carotid siphon.
The first branch of the ICA is the
ophthalmic artery.
The test for ECA vs ICA, you can “tap” which vessel?
superficial temporal artery.
Which vessel is normally high-resistance?
ECA
Intracranial Portions of ICA:
Supraclinoid
Cavernous (Siphon)
Petrous (base of skull)
Anterior Cerebral Artery (ACA)
Nourishes the anterior, superior and medial portions of the frontal lobes, as well as the medial surface of the cerebral hemispheres.
A1 Segment: from the ACA origin to the anterior communicating artery.
Middle Cerebral Artery (MCA)
The MCA courses laterally from the ICA bifurcation.
As it enters SYLVIAN FISSURE, the MCA splits into 2 (sometimes 3) branches. Superior & inferior.
Luminal diameter is 2.2-2.8 mm.
M1 Segment: from MCA origin. Encompasses MCA stem, bif, & proximal portions of all MCA divisions.
At the level of the _______ junction, the paired vertebral arteries join to form the basilar artery.
Pontomedullary Junction.
Basilar Artery
Gives off penetrating pontine branches and some cerebellar branches before bifurcating into the terminal posterior cerebral arteries (PCAs).
Posterior Cerebral Artery (PCA)
Supplies blood to the midbrain, thalamus, medial occipital & inferior temporal lobes.
P1 segment: extends from PCA origin to the Posterior communicating artery.
P2 Segment: arcs posteriorly.
The ______ Communicating Artery is the most variable of the network due to embryologic development of the vessel.
Posterior ComA.
Common Variant of the PcomA.
the PcomA persists as a larger vessel than the P1 segment of the PCA.
PcomA receives its blood supply primarily from the ______ 82% of the time, from the ____ 11%, and from the both 7%.
Basilar 82%
ICA 11%
The anterior circulation’s most common variant is:
hypoplasia of the AcomA.
Doubling ( 9-30%) of the AcomA is also a variant.
Most common variant of the Vertebral arteries is:
left side is larger than the right side.
T or F
Adequate pathways develop better in presence of slowly developing vascular disease.
true.
3 Mayjor Collateral Pathways:
1: Contralateral hemisphere
key is anterior communicating artery.
3 Mayjor Collateral Pathways:
2: Posterior to Anterior
flow is from vertebrobasilar circulation via posterior cerebral artery (PCA) and posterior communicating artery.
3 Mayjor Collateral Pathways:
3: ECA to ICA branches
utilizes ophthalmic artery as collateral.
Retrograde flow to distal ICA above occlusion.
TCD - Orbital Window
collateral flow from the ECA through the OA to the brain via the carotid siphon.
Dural sinuses
Endotheliallinedvenouschannelsbetweenlayers
of cranial dura mater
Most of the blood draining from the head passes into three pairs of veins:
Internal Jugular
External Jugular
Vertebral Veins
Dural Sinuses ( 6 ):
Superior Sagittal Sinus Inferior Sagittal sinus Straight Sinus Transverse Sinuses Sigmoid sinuses Cavernous sinus
Superifical venous system (3):
Superior Cerebral group
Middle cerebral group
Inferior cerebral group
Deep Venous system:
Great cerebral Vein of Galen- receives much of the deep venous flow. obstruction of this vessel leads to rapid death.
Intracranial Venous Drainage
Dural venous sinuses:
no valves
lined by endothelium
lie btw periosteal & meningeal layers of dura mater.
Superficial cerebral veins drain into Superior & Inferior Sagittal sinuses.
InferiorSS joins with the Vein of Galen to form the Straight Sinus.
Straight Sinus join to form a Confluence of Sinuses which turn into the Transverse Sinuses.
These become the Sigmoid Sinuses, which drain in the IJV.
The venous sinus that runs along the superior midline in an anterior-posterior direction is the:
Superior Sagittal Sinus
Straight sinuses join to form a confluence of sinuses which turn into the _______ sinuses.
Transverse sinuses.
The transverse sinuses becomes the ______ which then drains into the IJV.
Sigmoid sinuses.
