ACA/PCA

Question 1

What primitive arteries precede the ACA?

Answer 1

Primitive olfactory artery &laquo_space;Primitive ICA

Question 2

What is the extent of the A2 segment?

Answer 2

From the Acomm take off to the corpus fcallosum genu

Question 3

Where does the recurrent artery of heubner arise from?

Answer 3

A2 most commonly 50%
A1 45%
Acomm 5%

Question 4

What are the cortical branches of the ACA?

Answer 4

Orbitofrontal
Frontopolar
Callosomarginal
Pericallosal
Splenial

Question 5

What percentage of A1 segments are absent or hypoplastic? The contralateral ACA then supplies part or all of the normal ACA vascular territory in the opposite hemisphere
via a large ACoA and two normal distal

Answer 5

10-25%

Question 6

How to differentiate a bihemispheric ACA from an azygos ACA?

Answer 6

Bihemispheric (2-7%): If one A2 segment is hypoplastic and the other A2 divides into branches that provide the major blood supply to both hemispheres, a so-called bihemispheric ACA is present (Fig. 6-13A). This anomaly is found in 2% to 7%
of anatomic specimensTo distinguish from azygos–one should be able to identify a hyposplastic A2 on the opposite side

Azygos (0.2-4%) : If the embryonic median artery of the corpus callosum persists, an azygous ACA is formed. They also have been
reported in association with holoprosencephaly, neuronal migration anomalies, and an increased risk of aneurysm formation

Question 7

Where does the A2 stop and the A3 begin?

Answer 7

At the junction for the genu and the rostrum of the corpus callosum

A3 courses around the corpus callosum genu.

Other investigators have described two addition segments
(A4 andA5) that course above the corpus callosum
and are separated by the plane of the coronal fissure

Question 8

The A2 bifurcates into two main vessels? What are these?

Answer 8

The pericallosal and the callosomarginal arteries

Question 9

Name the four segments of the PCA

Answer 9

PI = precommunicating (mesencephalic) segment
P2 = ambient segment
P3 = quadrigeminal segment
P4 = calcarine segment

Question 10

The PCAs lie above which CN?

Answer 10

3 and 4

Question 11

In the ambient cistern P2 runs with which 2 structures?

Answer 11

Optic tract and basal vein of rosenthal

Question 12

Name the branches of
P1
P2

Answer 12

P1: Posterior thalamoperforating arteries (PTPA)
P2: Thalamo geniculate, Medial posterior choroidal (usually single), lateral posterior choroidal, anterior temporal artery and posterior temporal artery,

Question 13

What anterior circulation artery do the lateral choroidal arteries (&laquo_space;P2) anastomose with?

Answer 13

The anterior choroidal artery (&laquo_space;ICA, C7)

Question 14

What are the limits of the P3 PCAs?

Answer 14

From posterior midbrain to the calcarine fissure

Note: AKA quadrigeminal segment

Question 15

What are the branches of P3?

Answer 15

Medial branch: Parietooccipital artery, calcarine artery, splenial arteries (may arise from the parietooccipital artery)
Lateral branch: Anterior, medial and posterior inferior temporal arteries

Question 16

Where do the ff originate?

1. Anterior thalamoperforators
2. Posterior thalamoperforators
3. Thalamogeniculate

Answer 16

1. Posterior communicating
2. P1
3. P2

Question 17

What are the arteries above and below the calcarine artery on lateral angiographic view?

Answer 17

Above: Parietooccipital artery
Below: Posterior inferior temporal artery