Greenberg's - Vascular Anatomy Flashcards

1
Q

Origin: Recurrent artery of Heubner = medial striate artery

A

Junction of the ACA and A-Comm in 62%

Proximal A2 in 23%

A1 14%

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2
Q

Angiography: Circle of Willis

A

A balanced configuration of the CoW is present in only 18% of population

Hypoplasia of 1 or both p-comms occurs in 22-32%
- Absent or hypoplastic A1 segments occurs in 25%

The ACA pass over the superior surface of the optic chiasm

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3
Q

Anterior Cerebral Artery - A1

A

Precommunicating

ACA from origin to ACoA

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4
Q

Anterior Cerebral Artery - A2

A

Postcommunicating

ACA from ACoA to branch-point of callosmarginal

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5
Q

Anterior Cerebral Artery - A3

A

Precallosal

From branch-point of callosomarginal curving around the genu of the corpus callosum to superior surface of corpus callosum 3cm posterior to the genu

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6
Q

Anterior Cerebral Artery - A4

A

Supracallosal

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7
Q

Anterior Cerebral Artery - A5

A

Postcallosal

Terminal branch

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8
Q

Middle Cerebral Artery - M1

A

MCA from origin to bifurcation
- Classical bifurcation into relatively symmetrical superior and inferior trunks is seen in 50%
- No bifurcation occurs in 2%
25% have a proximal branch (middle trunk) arising from the superior (15%) or inferior (10%) trunk creating a pseudotrifurcation

Pseudotetrafurcation occurs in 5%

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9
Q

Segments of the ICA - Cincinnati system

A
C1 cervical
C2 petrous
C3 lacerum
C4 cavernous
C5 clinoid
C6 ophthalmic
C7 communicating
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10
Q

Middle Cerebral Artery - M2

A

MCA trunks from bifurcation to emergence from Sylvian fissure

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11
Q

Middle Cerebral Artery - M3 to 4

A

Distal branches

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12
Q

Middle Cerebral Artery - M5

A

Terminal branch

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13
Q

Posterior Cerebral Artery - P1

A

PCA from origin to P-Comm artery

- Long and short circumflex and thalamoperforating arteries arise from P1

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14
Q

Posterior Cerebral Artery - P2

A

PCA from origin of P-Comm to the origin of inferior temporal arteries

P2 traverses the ambient cistern

Hippocampal, anterior temporal, peduncular perforating and medial posterior choroidal arteries arise from P2

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15
Q

Posterior Cerebral Artery - P3

A

PCA from origin of the inferior temporal branches to the origin of the terminal branches

P3 traverses the quadrigeminal cistern

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16
Q

Posterior Cerebral Artery - P4

A

segment after the origin of the parieto-occipital and calcarine arteries, includes cortical branches of the PCA

17
Q

External Carotid

A
Superior thyroid artery - 1st anterior branch
Ascending pharyngeal artery
Lingual artery
Facial artery
Occipital artery
Posterior auricular
Superifical temporal
Internal maxillary artery
18
Q

Ascending pharyngeal artery

A

Neuromeningeal trunk of the ascending pharyngeal artery - supplies IX, X and XI
- important when embolising glomus tumours, 20% = lower cranial nerve palsy if this branchi soccluded

Pharyngeal branch usually the primary feeder for jugular foramen tumours - essentially the only cause of hypertrophy of the ascending pharyngeal artery

19
Q

Facial artery

A

Branches anastamose with ophthalmic artery

- important in collateral flow with ICA occlusion

20
Q

Occipital artery

A

Supplies posterior scalp

21
Q

Branches: Superficial temporal artery

A

Frontal branch

Parietal branch

22
Q

Branches: Internal Maxillary Artery

A

Initially within parotid gland

Middle meningeal artery

  • Anterior branch
  • Posterior branch

Accessory meningeal

Inferior alveolar

Infra-orbital

Distal branches of which may anastomose with branches of ophthalmic artery in the orbit

23
Q

Internal Carotid Artery - C1

A

Cervical

  • Begins in the neck at carotid bifurcation where the common carotid artery divides into ICA and ECA
  • Travels in carotid sheath with IJV and X, encircled with PGSN

C1 ends where teh ICA enters carotid canal of petrous bone

No branches

24
Q

Internal Carotid Artery - C2

A

Petrous

  • Surrounded by PGSNs
  • Ends at posterior edge of foramen lacerum, inferomedial to the edge of the Gasserian ganglion in Meckel’s cave
  1. Vertical segment - ICA ascends then bends as the…
  2. Posterior loop - anterior to cochlea, bends antero-medially becoming the…
  3. Horizontal segment - deep and medial to greater and lesser superficial petrosal nerves, anterior to tympanic membrane
25
Q

Internal Carotid Artery - C3

A

Lacerum

  • ICA passes over the foramen lacerum forming the lateral loop
  • Ascends in the canalicular portion of the foramen lacerum to juxtasellar position
  • Pierces the dura as it passes the ptrolingual ligament to become the cavernous segment

Branches (usually not visible angiographically):

  1. Caroticotympanic (inconsistent) - supplies tympanic cavity
  2. Pterygoid (vidian) - passes through foramen lacerum, present in only 30% may continue as artery of pterygoid canal
26
Q

Internal Carotid Artery - C4

A

Cavernous

  • covered by vascular membrane lining sinus
  • surrounded by PGSNs
  • Passes anterior then superio-medially, bends posteriorly (medial loop of ICA)
  • Travels horizonally and bends anteriorly (part of anterior loop of ICA) to anterior clinoid process
  • Ends at proximal dural ring (incompletely encircles ICA)

Multiple branches:

  1. Meningohypophyseal trunk (largest and most proximal)
  2. Anterior Meningeal artery
  3. Anterior to inferior portion of Cavernous sinus (present in 80%)
  4. Capsular arteries of McConnell (in 30%) - supply the capsule of pituitary
27
Q

2 Causes of Prominent MHT

A

Tumour - usually petroclival meningioma

Dural AVM

28
Q

Branches of meningohypophyseal trunk

A

Artery of tentorium = artery of Bernasconic and Cassinari - blood supply of petroclival meningioma

Dorsal meningeal artery = dorsal clival artery

Inferior hypophyseal artery - supplies posterior lobe of pituitary
- Post partum occlusion causes pituitary infarcts (sheehan’s necrosis), DI is rare because the stalk is spared

29
Q

Internal Carotid Artery - C5

A

Clinoid
- Begins at proximal dural ring, ends at distal dural ring (which completely encircles ICA) where the ICA becomes intradural

30
Q

Internal Cartoid Artery - C6

A

Ophthalmic
- Begins at distal dural rings, ends just proximal to p-comm

Branches:

  1. Ophthalmic artery
    - Origin from the ICA is distal to the cavernous sinus in 89% (intracavernous in 8%, ophthalmic artery is absent in 3%)
    - Can vary from 5mm anterior to 7mm posterior to the anterior clinoid
    - Passes through optic canal into the orbit
    - Characteristic bayonet-like ‘kink’ on lateral angiogram
  2. Superior hypophyseal artery
    - supplies anterior lobe of pituitary and stalk
    - 1st branch of supraclinoid ICA
31
Q

Internal Carotid Artery - C7

A

Communicating

  • Begins just proximal to P-comm origin, travels between CN II and III
  • Terminates just below anterior perforated substance where it bifurcates to the ACA and MCA

Branches:

  1. Posterior communicating artery
    - Few anterior thalamoperforators, supply optic tract, chiasm and posterior hypothalamus
    - Plexal segment: enters supracornual recess of temporal horn, supplies only this portion of choroid plexus
    - Cisternal segment: passes through crural cistern
  2. Anterior choroidal artery
    - Take off 2-4mm distal to P-com, supplies variable portion of optic tract, medial globus pallidus, genu of internal capsule (in 50%), inferior half of posterior limb of IC, uncus, retrolenticular fibres (optic radiation), lateral geniculate body; for occlusion syndromes
32
Q

Internal Carotid Artery - Carotid Siphon

A

Not a segment

Region incorporating the cavernous, ophthalmic and communicating segments.

Begins at the posterior bend of the cavernous ICA and ends at the ICA bifurcation

33
Q

Differentiating a P-Comm from ACh on arteriogram

A
  1. P-Comm origin is proximal to that of the anterior choroidal artery (ACh)
  2. P-Comm is usually larger than ACh
  3. P-Comm usually goes up or down a little, then straight back and usually bifurcates
  4. ACh usually has a superior ‘hump’ (plexal point) where it passes through the choroidal fissure to enter the ventricle.