paramedianpontina

Paramedian pontina, or the paramedian pontine region, is a neuroanatomical term describing the medial and paramedial portions of the pons, the brainstem segment between the midbrain and medulla. It commonly refers to the vascular territory supplied by the paramedian perforating branches of the basilar artery, as well as the neural structures located in the ventral and medial pons.

Anatomy and components: The paramedian pontine region contains descending motor pathways from the cerebral cortex (the corticospinal and corticobulbar fibers) as they traverse the basis pontis, along with components of the pontine tegmentum and adjacent sensory relay pathways. The pontine reticular formation and nearby cranial nerve nuclei associated with the pons are connected to this area, though the exact borders vary among sources.

Blood supply: The territory is supplied primarily by the paramedian branches of the basilar artery, with perforating arteries penetrating the ventral pons. Disease of the vertebrobasilar system can compromise this supply, leading to focal pontine deficits.

Clinical significance: Ischemic or hemorrhagic lesions in the paramedian pontine region can produce contralateral motor weakness, cranial nerve palsies, or combined syndromes depending on the extent. Bilateral involvement of the ventral pons may result in locked-in syndrome, characterized by preserved consciousness and vertical eye movements but loss of most voluntary movement. Hypertensive hypertensive lacunar infarcts are a common etiological mechanism in this region.

See also: basilar artery, pontine arteries, pontine tegmentum, PPRF, locked-in syndrome.