Vascular territories of Brain stem and Infarct correlation

The arteries of the brain stem form four groups of penetrating parenchymal vessels; the anteromedial, anterolateral, lateral and posterior arterial groups.
Each group irrigates the corresponding anteromedial, anterolateral, lateral or posterior territory within the substance of the brain stem.

There are two possible systems of nomenclature.
1 . Foix and Hillemand Classification 

The penetrating branches arising from the surface vessels are divided into PM (paramedian), SC (short circumferential), and LC (long circumferential) vessels.

2.  Gillilan and Lazorthes et al. Classification

AM (anteromedial)
AL (anterolateral)
L (lateral) and
P (posterior) group.

Reference : Duvernoy’s Atlas of the Human Brain Stem and Cerebellum

Examples: 

Ax T2wi, Left side Medullary Infarction, Vascular territory : Antero Medial group / Para Median branches.

Ax FLAIR, Left side Medial Medullary Infarction, Vascular territory : Antero Lateral group / Short circumferential branches.

Ax T2wi, Left side medullary infarction, Vascular territory : Lateral group / Short circumferential branches.

Ax T2wi, Left side medullary infarction, Vascular territory : Posterior group / Long circumferential branches.

Ax T2wi, Midline medullary infarction, Vascular territory : Bilateral Antero Medial group / Para median branches.

Ax T2wi, Pontine infarction on left side, Vascular territory : Antero Medial group / Para median branches.

Ax T2wi, Pontine infarction on left side, Vascular territory : Antero Lateral group / Short circumferential branches.

Ax T2wi, Pontine infarction, Vascular territory : Bilateral Antero Medial group / Para median branches.

Ax T2wi, Pontine infarction, Vascular territory : Antero Lateral group / Short circumferential branches.

Ax T2wi, Pontine infarction and adjacent cerebellar infarct, Vascular territory : Posterior group / Long circumferential branches.

Ax T2wi, Mid brain infarction, Vascular territory : Antero Medial group / Para median branches.

Ax T2wi, Infarction involving mesencephalic mid brain, Vascular territory : Bilateral Antero Medial group / Para median branches.

Ax Diffusion, Recent Mid brain infarction, Vascular territory : Antero Lateral group / Short circumferential branches.