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The Role of a Transverse Arachnoidal Membrane Within the Interpeduncular Cistern in the Passage of Pantopaque into the Cranial Cavity

1965; Radiological Society of North America; Volume: 85; Issue: 5 Linguagem: Inglês

10.1148/85.5.914

1527-1315

Bernard S. Epstein,

Vestibular and auditory disorders

The passage of Pantopaque into the middle and anterior cranial fossae during myelography has received little attention. The medium enters the skull by way of the medullary, pontine, and interpeduncular cisterns. Occasionally the column is restrained in the interpeduncular cistern as if against a curtain, and spillage does not occur unless the head is flexed or tilted. In an effort to explain this, observations were made of the basilar cisterns at necropsy as the brain was removed from the cranium, and the basilar arachnoid dissected immediately thereafter. After removal of the calvarium, retraction of the frontal lobes brings the optic nerves and chiasm into view (Fig. 1, A). Arachnoidal tags pass to the chiasm. The infundibulum and tuberculum sellae appear when the optic nerves are cut and retracted (Fig. 1, B). The oculomotor nerves can be identified crossing the lateral aspects of the interpeduncular cistern to enter the cavernous sinuses (Fig. 1, C). When the tentorium cerebelli is dissected away the trigeminal and auditory nerves are seen crossing the cerebellopontine cisterns. The other cranial nerves can also be identified when the pons is pushed backward (Fig. 4, B). After the opening of the dural cover of Meckel's cave and the cavernous sinuses the oculomotor, trigeminal, and auditory nerves can be traced. The abducens nerves are seen closer to the midline, passing from the junction of the pons and medulla oblongata to the cavernous sinuses (Fig. 1, D). The trochlear nerves are situated more laterally. Passing from their emergence immediately behind the inferior colliculi they cross the superior cerebellar peduncles, wind around the cerebral peduncles near the pons, and pass along the free border of the tentorium cerebelli for a centimeter or two. Piercing the dura mater just behind the posterior clinoid processes, the trochlear nerves enter the cavernous sinuses. These nerves are not visible on the present preparations until after the brain is removed (Fig. 2, B). The clivus and the dorsum sellae form the floor of the medullary, pontine, and interpeduncular cisterns. The lateral cerebellopontine cisterns merge with the midline pontine cistern. The optic nerves, the chiasm, and the optic tracts traverse the superior portion of the interpeduncular cistern, extending posteriorly from the optic foramina. The chiasmatic cistern lies anterior to the optic chiasm and nerves and also occupies a small space behind the chiasm between the diverging optic tracts. The infundibulum is situated immediately behind the chiasm. A heavy arachnoidal membrane envelops this area. Extending caudally and laterally, this continues in a broad sheet which covers the floor of the interpeduncular cistern (Fig. 2, A).