Mesencephalic branches of basilar artery

Mesencephalic branches of the basilar artery (Perforating branches to the midbrain) are small arterial vessels that arise from the basilar artery and its major branches to supply the mesencephalon (midbrain). These branches can be categorized based on their origin and the territory they supply:

• Anteromedial (paramedian) group: Supply the medial midbrain structures including the oculomotor nerve fascicles, red nucleus, medial longitudinal fasciculus, and decussation of the superior cerebellar peduncle.

• Anterolateral (short circumferential) group: Supply the cerebral peduncle and lateral substantia nigra.

• Lateral and dorsal (long circumferential) group: Supply the lateral tegmentum, colliculi, and the periaqueductal gray matter. These are largely derived from the SCA and posterior cerebral artery as they course around the midbrain.

Clinical Significance

Occlusion of these small perforating branches results in well-recognized midbrain stroke syndromes, including Weber syndrome (anteromedial territory ipsilateral CN III palsy with contralateral hemiparesis), Benedikt syndrome (tegmental territory CN III palsy with contralateral tremor/ataxia), and Claude syndrome (involvement of the red nucleus and superior cerebellar peduncle).