Retraction of Fornix to Demonstrate Internal Cerebral Veins. The right lateral ventricle has been opened to expose the Foramen of Monro, choroid plexus and anterior thalamus.  The fornix and septum pellucidum have been retracted medially to demonstrate the thalamostriate, anterior septal, and internal cerebral veins.  (Image courtesy of AL Rhoton, Jr.)