lecture 29 cranial blood supply

R and L common carotid aa, R and L vertebral aa

what are the two major sets of vessels that supply blood to the head (brain, face, and scalp)?

anterolateral

the common carotid aa run along the ___ aspect of the vertebral compartment within the carotid sheath

midpoint of the cervical spine (C4)

the common carotid aa split into external and internal aa near the...

scalp and face

what do the external carotid aa supply blood to?

medial and anterior portions of the cerebrum except for parts of the temporal and occipital lobes

what do the internal carotid aa supply blood to?

no

do the internal carotid aa give off branches before entering the cranial cavity?

carotid canals

each internal carotid a enters the cranial cavity through the ___

cranial vault

after passing through the carotid canals, the internal carotid aa take several turns before entering what?

foramen lacerum

what do the internal carotid aa enter the cranial vault through?

false

true or false: the foramen lacerum is open on its inferior aspect

anterior cerebral aa and middle cerebral aa

what are the two terminal branches of the internal carotid a?

anterior circulation of the brain

the internal carotids and their branches are collectively referred to as the...

60%

the internal carotids and their branches provide what percentage of blood flow to the cerebrum?

1st portion of subclavian a

what do the vertebral aa arise from?

C6

the vertebral aa enter the transverse foramen of the ___ vertebrae and travel up through the transverse foramina to the atlas

doppler ultrasound (not palpable)

what may be used to visualize blood flow through the vertebral aa?

40%

the vertebral aa provide ___ of the blood flow to the cerebrum

brainstem and cerebellum

what do the vertebral aa perfuse?

false, passes over it

true or false: the vertebral a passes through the transverse foramen of the C7 vertebrae

cervical, atlantic, and intracranial parts

what are the three portions that the vertebral aa are divided into?

portion that extends through the transverse foramina of the C1-C6 vertebrae

describe the cervical portion of the vertebral aa

wraps posterior to the lateral mass before passing through the foramen magnum and perforating through the dura

describe the atlantic part of the vertebral aa

found within the cranial cavity prior to the formation of the basilar a

describe the intracranial part of the vertebral aa

basilar a

the two vertebral aa end by uniting to form the...

along the rounded ventral surface of the pons (basilar pons)

where does the basilar a lie?

combined vertebral and basilar aa

what is the term vertebrobasilar a or vertebrobasilar system used to denote?

Vertebrobasilar insufficiency

what does VBAI stand for?

a medical condition where there is reduced blood flow to the back of the brain, specifically through the vertebral and basilar arteries

what is VBAI?

rapid rotational movements, smoking, high BP, OC

what increases the risk for VBAI?

posterior cerebral aa

the basilar a ascends along the pons giving off several pairs of small branches before bifurcating into two terminal branches ____

circle of Willis

the internal carotid and vertebral aa form an anatomosis called what?

base of brain

the circle of Willis loops around the brainstem at the...

anterior cerebral aa (ACA), middle cerebral aa (MCA), and posterior cerebral aa (PCA)

from the circle of willis, what arises to supply the entire cerebrum?

sella turcica

the circle of willis forms a roughly circular structure surrounding the ___ on the inferior surface of the brain

posterior cerebral aa (2), posterior communicating aa (2), internal carotid aa (2), anterior cerebral aa (2), anterior communicating a (1)

what does the circle of willis consist of?

collateral circulation

what is the phenomenon called that explains how if one of the main aa is blocked in the circle of Willis, smaller aa that the circle supplies can receive blood from the other aa (because the carotid and basilar aa form a circle with their respective branches)?