SEPTUM PELLUCIDUM The septum pellucidum (also called the septum lucidum) is a thin, triangular, vertical membrane separating the lateral ventricles of the brain. It separates the anterior horn of the left and right lateral ventricles. It runs as a sheet from the corpus callosum down to the fornix. The septum pellucidum is located in the midline of the brain, between the two cerebral hemispheres. It is attached superiorly (above), anteriorly (in front), and inferiorly (below) to the corpus callosum, the large collection of nerve fibers that connect the two hemispheres. Inferiorly and posteriorly (in back), it is attached to the anterior part of the fornix. The septum pellucidum actually consists of two layers or laminae of both white and gray matter, called the laminae septi pellucidi. These layers are normally fused. Brain Architecture Management (BAMS) Maj (1997) – human paleocortex septal area septum pellucidum Bowden (2002) – human brain forebrain telencephalon cerebral cortex septum septal nuclei dorsal septal nucleus lateral septal nucleus medial septal nucleus nucleus of anterior commisssure nucleus of diagonal band nucleus of stria terminalis septofimbrial nucleus triangular septal nucleus septum pellucidum cave of septum pellucidum lamina of septum pellucidum Swanson (1992) – rat brain forebrain isocortex septal region bed nuclei of the stria terminalis bed nuclei of the anterior commissure lateral septal nucleus medial septal complex posterior septal complex septohippocampal nucleus subfornical organ Hof (2000) – mouse telencephalon neocortex septal region bed nucleus of the stria terminalis bed nucleus of the stria medullaris lateral septum complex medial septum complex posterior septum complex septohippocampal nucleus subfornical organ zona limitans Paxinos/Franklin (2001) – mouse forebrain cerebral cortex septum lambdoid septal zone lateral septal nucleus medial septal nucleus nucleus of the diagonal band septofimbrial nucleus septohippocampal nucleus Swanson (1998, 2004) – rat cerebrum cerebral cortex Dong (2007) – mouse cerebrum cerebral cortex cortical plate isocortex MA brain (p) forebrain (p) telencephalon (synonym: cerebrum) (p) cerebral hemisphere (synonym: cerebrum) (p) cerebral cortex (p) neocortex (synonym: cerebral cortex) (p) septum of telencephalon (MA:0000924) (septal area, septal region) (p) septal nucleus (MA:0002978) (i) bed nucleus of stria terminalis (i) lateral septal complex (i) medial septal complex (i) posterior septal complex (i) septohippocampal nucleus (i) subfornical organ (p) septum pellucidum (MA:0002979) (synonym: septum lucidum) FMA .