Tentorial notch

The authors explained the ipsilateral hemiparesis by invoking the Kernohan-Woltman notch phenomenon, in which intracranial mass lesions compress the cerebral peduncle on the opposite side against the tentorial notch, interrupting the fibers of the cerebrospinal tract. The subdural hematoma was aspirated and she was discharged with minimal weakness of the right leg. 

The free or inner concave border forms the tentorial notch, which surround the midbrain and is classically described as attaching to the anterior clinoid processes of the sphenoid. The attached or outer convex border is classically described as attaching to five areas the transverse ridge of the sulcus of the transverse sinus of the occiput, the posteroinferior angle of the parietal bone at the asterion, the mastoid portion of the temporal bone, the petrous ridge of the temporal bone, and the posterior clinoid process of the sphenoid. 

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