Brainstem Arteries: Specific Vascular Territories

Medulla

• Key medullary arterial vessels are: the anterior spinal artery and the posterior inferior cerebellar arteries.
• The common source for these arteries is the vertebral arteries.
  • As a clinical corollary, ischemia to the posterior inferior cerebellar artery results in lateral medullary syndrome, called Wallenberg's syndrome.

Groups/Supply

• The anteromedial group is supplied by the anterior spinal artery and direct vertebral artery branches.
• The anterolateral group is supplied by the anterior spinal artery and the posterior inferior cerebellar arteries.
• The lateral group is supplied by the posterior inferior cerebellar arteries.
• The posterior group is supplied by the posterior inferior cerebellar and posterior spinal arteries.

Pons

• Most of the pontine arterial supply comes in the form of circumferential artery branches that travel progressively farther distances to their targets.
• The posterior portion of the pons receives additional supply from the anterior inferior cerebellar artery, inferiorly, and the superior cerebellar artery, superiorly.
• The common source for these arteries is the basilar artery.
  • Basilar ischemia can produce pontine basis strokes, which can cause locked-in syndrome.

Groups/Supply

• The anteromedial group is supplied by the pontine paramedian arteries.
• The anterolateral group is supplied by the short pontine circumferential arteries.
• The lateral group is supplied by the long pontine circumferential arteries and the anterior inferior cerebellar arteries.
• The posterior group is supplied by the superior cerebellar arteries.

Note that the posterior group is found only in the upper pons — it is not present in the mid- or lower pons.

Midbrain

• The PCAs or distal basilar artery supply the midbrain, either directly or via smaller branches.
  • When basilar clot produces ischemia to the proximal PCAs, large midbrain strokes can occur and produce a so-called "top of the basilar" syndrome.

Groups/Supply

• The anteromedial group is supplied by basilar tip and proximal PCA branches.
  • From inferior to superior, these branches are the inferior and superior paramedian mesencephalic arteries and the thalamoperforate arteries.
• The anterolateral group is supplied by PCA branches: the collicular and posteromedial choroidal arteries.
• The lateral and posterior groups are also supplied by the collicular and posteromedial choroidal arteries in concert with the superior cerebellar arteries.