Cranial nerve schwannomas most commonly arise from Schwann cells that myelinate the distal aspect of the vestibular division of the 8th cranial nerve. Vestibular schwannomas, sometimes referred to by the double misnomer “acoustic neuroma” (it is a double misnomer because they are not neuromas and they do not usually involve the acoustic division of cranial nerve 8), often exhibit the characteristic “ice cream cone” or “snow cone” sign on MRI. Vestibular schwannomas typically originate within the bony confines of the internal auditory canal where they form the “cone”. They grow in the path of least resistance toward the posterior fossa where they burgeon into the cerebellopontine angle space to form the bulk of the neoplasm that resembles a scoop of ice cream atop a cone.
For further study on this topic and others related to neuropathology and neuroanatomy, the following books come highly recommended, and a small portion of the proceeds (or any Amazon purchase through these links) help with expenses of hosting this site:
Adventures in Neuropathology 
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