Cave of septum pellucidum
The cave of septum pellucidum (CSP), cavum septi pellucidi, or cavity of septum pellucidum is a slit-like space in the septum pellucidum that is present in fetuses but usually fuses during infancy. The septum pellucidum is a thin, laminated translucent vertical membrane in the midline of the brain separating the anterior horns of the right and left ventricles. It lies posterior to the corpus callosum. Persistence of the cave of septum pellucidum after infancy has been loosely associated with neural maldevelopment and several mental disorders that correlate with decreased brain tissue. The cave of septum pellucidum is bounded anteriorly by the genu of the corpus callosum, superiorly by the body of the corpus callosum, posteriorly by the anterior limb and pillars of the fornix, inferiorly by the anterior commissure and the rostrum of the corpus callosum, and laterally by the leaflets of the septum pellucidum. In prenatal development of the fetus, the laminae of the septum pellucidum separate to form a small cavity – the cave of septum pellucidum. This is an important normal structure to identify in the sonographic assessment of the fetal brain. In post-natal life, the laminae of the septum pellucidum usually fuse, which obliterates the cavum.