Uncal herniation occurs when:
A) The hippocampal gyrus shifts from the middle fossa through the tentorial notch into the posterior fossa.
B) The diencephalon shifts from the middle fossa straight downward through the tentorial notch into the posterior fossa.
C) The cingulate gyrus shifts under the falx cerebri.
D) A cerebellar tonsil shifts through the foramen magnum.

Question

Quizplus · Accepted Answer

Uncal herniation (i.e.,hippocampal herniation,lateral mass herniation)occurs when the uncus or hippocampal gyrus (or both)shifts from the middle fossa through the tentorial notch into the posterior fossa.This shift results in the compression of the ipsilateral third cranial nerve (CN),impairing parasympathetic function.This impairment is carried on in the periphery of the nerve,then in the contralateral third CN,and finally in the mesencephalon,inducing coma.The other options do not appropriately describe when uncal herniation occurs.

Uncal Herniation Occurs When