CISS 3D axial and TIRM T1 coronal showing normal trigeminal nerve.
1. intra-axial: 4 nuclei (1 motor - mastication, 3 sensory)
2. cisternal: large sensory and small motor root. From root entry zone of pons courses anterosuperiorly through prepontine cistern beneath petrous apex, passes through porus trigeminus (dura mater opening) to enter Meckels cave
3. interdural: Meckels cave (filled with CSF), continuous with prepontine cistern. Trigeminal ganglion (Gasserian ganglion) is located inferiorly in meckels cave
4. extracranial: 3 divisions, ophthalmic, maxillary and mandibular