#06 Flashcards
The arterial supply to the spinal cord is largely a, while the blood supply of the
brain is b
a: segmental
b:regional
Almost all venous blood drains into the a and then into the b
a: dural sinuses
b: internal jugular vein
Because they lack anastomoses with adjoining vessels, occlusion of most cerebral vessels
(by thrombus, etc.) leads to
regional ischemia and tissue death
The internal carotid artery (ICA) is a branch of the a. The artery then loops superiorly and posteriorly before dividing into its terminal braches: b,c.
a: common carotid artery
b: anterior cerebral artery
c: middle cerebral artery
The vertebral arteries are branches of the a. The two vessels then anastomose to form the b. B is the main blood supply to c and is connected to the carotid system via the arterial d
a: subclavian artery.
b: basilar artery
c: pons and midbrain
d: Circle of Willis
The basilar artery
typically ends by
bifurcating into paired a, which continue into the b
a:posterior cerebral
arteries (PCA),
B:
In total, the vertebrobasilar circulation supplies:
* The spinal cord (via a)
* The medulla (via b)
* The pons (via c)
* The midbrain (mainly via d)
* The cerebellum (via e)
* The thalamus (via f)
* Inferior temporal lobe and occipital lobe (f)
a: anterior and posterior spinal arteries
b: the vertebral artery and its branches
c: the basilar artery and its branches
d: the posterior cerebral artery – PCA
e: PICA, AICA, and SCA branches
f: PCA
After supplying the midbrain, the PCA supplies the a and ends in the inferior and lower lateral surfaces of the b and medial surface of the c. Calcarine branches of PCA supplies the d, so strokes involving PCA typically result in e
a: thalamus
b: temporal lobe
c: occipital lobe
d: visual cortex (which is mapped on either side of the calcarine sulcus)
e: prominent visual
deficits.
Mq is frequently involved in
hemorrhagic strokes
ACA supply the portions of the primary motor and sensory cortices dedicated
to
the lower limb and perineum, trunk, as well as proximal parts of the upper extremity, feet
a can compensate for decreases in blood flow in
one or other of the circulations.
the Circle of Willis
Ischemic strokes
Blood supply is interrupted to a focal area of the brain with damage due to loss of oxygen
and essential nutrients
TIA = “transient ischemic attack”
o Sudden onset focal signs
o Short duration <24 hours, recently proposed <1 hour
o No brain injury on imaging
watershed zones
Watershed zones are border zones between the territories of two cerebral arteries, such as
between anterior and middle cerebral arteries, or between middle and posterior cerebral
arteries. These areas of non-overlap are susceptible to ischemic stroke
Shoulder and upper trunk areas of motor cortex are vulnerable in the
MCA/ACA watershed
zone. Bilateral infarct here (grey regions below) results in inability to abduct arms and flex
elbows:
2 major types of hemorrhagic strokes
- Intracranial hemorrhage
o Bleeding directly into brain tissue
o Results from hypertensive hemorrhage (leads to hyperplasia within the vessel wall, causes “breaks”), atherosclerosis, brain
tumors, or certain medications
o Focal deficits - Subarachnoid hemorrhage
o Bleeding surrounding brain tissue
o Results from arteriovenous
malformation (AVM), trauma, or
ruptured aneurysm
o Mass effect and subsequent herniation are risks
Most cerebral
aneurysms occur in the
vicinity of the circle of Willis, commonly in the anterior circulation
vertebral arteries supply
spinal cord
PICA, ASA, PSA, vertebral artery
The great radicular artery (of Adamkiewicz) is important for supplementing the supply of the
lower thoracic and upper lumbar cord
Basilar artery ends in a, which supply
a: paired posterior cerebral arteries
the midbrain, thalamus, and posterior parts of the cerebral cortex
M1 supply
basal ganglia
MCA supplies sensory and motor areas associated with
face and upper body
ACA supplies sensory and motor areas associated with
trunk and lower body
Anterior choroidal artery (AChA) supplies:
Choroid plexus of lateral ventricles
Optic tract
Small part of thalamus
Small part of basal ganglia
Hippocampus (with PCA)
Amygdala
Posterior limb of internal capsule
M2 (Superior covers a, Inferior covers b)
a lateral frontal lobe
b Parietal and Temporal lobes
PICA
Dorsal and lateral medulla, posterior inferior cerebellum
AICA
anterior inferior cerebellum, lateral pons
