The cranial meninges: anatomic considerations.

The anatomy of the cranial dura and leptomeninges is both intricate and complex. A thorough discussion of the protective covering of the brain including the dura, arachnoid, and pia is provided on both gross and microscopic levels. An attempt to include issues of clinical relevance is made, highlighting the Virchow-Robin spaces and the optic sheath. In addition, the normal appearance of the dura and leptomeninges on MRI is presented to establish a framework for the discussion of leptomeningeal pathology.