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. 2022 Feb;43(2):167–175. doi: 10.3174/ajnr.A7309

FIG 6.

FIG 6.

Illustration of arachnoid membranes in relation to the neurovascular structures in the interpeduncular and prepontine cisterns in the coronal (A) and sagittal (B) planes. The LM runs posterior-superiorly from the dorsum sellae and posterior clinical process. Its diencephalic leaf continues to run posterior-superiorly and attaches to or just anterior to the mammillary bodies, separating the interpeduncular cistern from the chiasmatic cistern. The mesencephalic leaf of the LM extends posteriorly and is divided by the oculomotor nerves into medial and lateral parts. The medial part, attached to the distal basilar artery or the pontomesencephalic junction, separates the interpeduncular cistern from the prepontine cistern. The lateral parts, attached to the tentorium and the mesial temporal lobes, separate the ambient cisterns from the cerebellopontine cisterns. The anterior pontine membranes run on either side of the basilar artery and are medial to the abducens nerves, separating the prepontine cistern from the cerebellopontine cisterns. The medial pontomedullary membrane, located in the midline portion of the pontomedullary sulcus, separates the prepontine cistern from the premedullary cistern. The lateral pontomedullary membranes, located in the lateral portion of the pontomedullary sulcus, separate the cerebellomedullary cisterns from the cerebellopontine cisterns. The numbers represent the following: 1) diencephalic leaf of the LM; 2) medial attachment of the mesencephalic leaf of the LM; 3) lateral attachment of the mesencephalic leaf; 4) anterior pontine membrane; 5) medial pontomedullary membrane; 6) lateral pontomedullary membrane. III indicates the oculomotor nerve; V, trigeminal nerve; VI, abducens nerve; AC, ambient cisterns; CC, chiasmatic cistern; CM, cerebellomedullary cistern; CP, cerebellopontine cistern; IP, interpeduncular cistern; MB, mammillary bodies; PCA, posterior cerebral artery; PM, premedullary cistern; PP, prepontine cistern; SCA, superior cerebellar artery. Reproduced with permission from Frank Gaillard and Radiopaedia.org. Copyright (2021) Radiopaedia.