Lateral pontomedullary membrane

The lateral pontomedullary membrane separates the cerebellomedullary cistern from the cerebellopontine cistern.

Insertions: from the VI nerve arachnoid cover at the pontomedullaris junction - laterally projected to the IX nerve arachnoid cover - finally blends with the cerebellar surface arachnoid cover I near the midline, this layer gets thicker but with an orifice for vertebrobasilar confluence and passage

Main relations: conforms the floor of the prepontine cistern and cerebellopontine cistern, separating them from the premedullaris and lateral cerebellomedullaris, respectively