A = fornix

B = mamillary body

C = pons

D = thalamus

E = inferior coliculus

F = splenium of corpus collasum

A = Caudate

B = internal capsule

C = Insula

D = Putamen

E = Globus palidus

D+E = Lentiform nucleus

Kernohan's notch is a cerebral peduncle indentation associated with some forms of transtentorial herniation (uncal herniation).[1][2]

It is a secondary condition caused by a primary injury on the opposite hemisphere of the brain.[3]

Kernohan's notch is an ipsilateral condition, in that a left-sided primary lesion (in which Kernohan's notch would be on the right side) evokes motor impairment in the left side of the body and a right-sided primary injury evokes motor impairment in the right side of the body.