Collateral circulation — Flashcards

Flashcard 1: In the Circle of Willis, which vessel connects the two anterior cerebral arteries?

Answer: Anterior communicating artery (ACom)

Extra: The anterior communicating artery is the most common site for berry (saccular) aneurysms. Rupture leads to subarachnoid hemorrhage, while large aneurysms can compress the optic chiasm, leading to bitemporal hemianopsia.

Flashcard 2: Which vessel of the Circle of Willis arises from the terminal bifurcation of the basilar artery?

Answer: Posterior cerebral artery

Extra: The posterior cerebral artery (PCA) arises from the terminal bifurcation of the basilar artery. It supplies the occipital lobe and the inferior portion of the temporal lobe. It is connected to the internal carotid artery via the posterior communicating artery, completing the posterior part of the Circle of Willis.

Flashcard 3: The _____ branches of the posterior cerebral artery supply the splenium, parahippocampal gyrus, and fusiform gyrus

Answer: cortical

Extra: The **cortical branches** of the PCA supply the splenium of the corpus callosum and the medial and inferior surfaces of the temporal and occipital lobes (including the parahippocampal and fusiform gyri). The **central (deep) branches** (e.g., thalamogeniculate, thalamoperforating) supply the thalamus and midbrain.

Flashcard 4: The macula is spared during posterior cerebral artery infarct due to collateral circulation with the _____ artery

Answer: middle cerebral

Flashcard 5: Which artery connects the internal carotid artery to the posterior cerebral artery in the Circle of Willis?

Answer: Posterior communicating artery

Extra: Aneurysms of the posterior communicating artery (PCoA) are a common cause of third nerve (oculomotor) palsy.

Flashcard 6: What structure is most commonly compressed by an aneurysm of the anterior communicating artery?

Answer: Optic chiasm compression, resulting in bitemporal hemianopia.

Extra: Aneurysms of the anterior communicating artery (ACom) are the most common site of Berry aneurysms in the Circle of Willis. Due to their location, they can compress the optic chiasm, leading to visual field defects.

Flashcard 7: An aneurysm of which artery is most commonly associated with a CN III palsy?

Answer: CN III (Oculomotor nerve) palsy

Extra: Aneurysms of the posterior communicating artery (PCoA) typically cause a CN III palsy with pupil involvement (mydriasis), because the parasympathetic fibers are superficial on the nerve. Findings: Ptosis, "down and out" eye position, and a dilated pupil.

Flashcard 8: Where do saccular "berry" aneurysms tend to occur?

Answer: bifurcations in Circle of Willis; especially anterior and posterior communicating arteries

Flashcard 9: Identify the branch of the vertebral artery labeled as number 3 in the provided image.

Answer: posterior spinal arteries

Flashcard 10: Identify the artery in the vertebrobasilar system labeled as number 9 (the vessel formed by the union of branches from both vertebral arteries descending the spinal cord):

Answer: Anterior spinal artery

Extra: The anterior spinal artery is formed by the union of two small branches from the vertebral arteries. It descends in the anterior median fissure and supplies the anterior two-thirds of the spinal cord.