Arterial Supply to the Ventromedial Pons
The ventromedial portions of the pons are predominantly perfused by paramedian branches of the basilar artery.
Anatomic Basis
The basilar artery gives rise to several distinct types of pontine arteries that supply different regions of the pons 1:
- Paramedian branches (Type 1) arise directly from the basilar artery and penetrate the ventromedial pons along the basilar sulcus, supplying the anteromedial pontine structures 1, 2
- These vessels average 0.39 mm in diameter and number approximately 5.8 perforating arteries along the basilar artery 2
- Short circumferential branches (Type 2) supply more lateral pontine regions, not the ventromedial areas 1, 3
- Long circumferential branches (Type 4) course around the pons to supply lateral and posterior territories 1
Clinical Correlation with Infarction Patterns
The vascular territory distribution is clearly demonstrated by pontine infarction patterns:
- Paramedian pontine infarctions (30% of pontine strokes) result from occlusion of these paramedian branches and affect the ventromedial pons 2
- Bilateral paramedian infarctions create the characteristic "heart appearance" sign on MRI, confirming that bilateral paramedian and short circumferential arteries supply the anteromedial pons 3
- These infarctions are typically isolated, unilateral, and can occur at any pontine level (lower 23.3%, middle 10%, rostral 26.7%) 2
Pathophysiologic Mechanisms
Ventromedial pontine ischemia occurs through specific mechanisms:
- Atherosclerotic or thrombotic involvement of paramedian branches is the primary mechanism 3
- Pontine Warning Syndrome results from intermittent hypoperfusion in these terminal paramedian arteries with insufficient collateral flow 4
- Basilar artery branch disease affecting these perforating vessels can cause fluctuating neurological deficits that correlate with blood pressure changes 4
Key Anatomic Distinctions
Understanding which vessels do NOT supply the ventromedial pons is clinically important:
- Anterior inferior cerebellar arteries (AICA) participate in pontine blood supply in only 12.5% of cases, primarily lateral regions 1
- Superior cerebellar arteries (SCA) contribute to pontine perfusion in only 2.5% of cases 1
- Posterior inferior cerebellar arteries (PICA) supply the medulla and cerebellum, not the pons 5