Efferents also project to the medial habenular nucleus and to certain midline thalamic nuclei. This is through the medial forebrain bundle. It includes noradrenergic afferents from the locus ceruleus (A1) and medullary (A2) cell groups dopaminergic afferents from the ventral tegmental region (A10) and serotoninergic afferents from the midbrain raphe nuclei.Įfferents project from the lateral septum to the medial and lateral preoptic areas the anterior hypothalamus and the supramammillary and midbrain ventral tegmental area. The lateral septum is greatly innervated in a monoaminergic manner. Afferents arise from the preoptic area lateral hypothalamic area and the anterior, paraventricular, and ventromedial hypothalamic nuclei. They have fibers of the fornix that begin in the hippocampal fields CA1 and CA3, as well as the subiculum. Major afferents to this area end mostly in the lateral septal nucleus. Ĭaudal group-the fimbrial and triangular septal nuclei.Medial group-the medial septal nucleus and the nucleus of the diagonal band of Broca Ventral group-the lateral septal nucleus ĭorsal group-basically, the dorsal septal nucleus.Under this area, the septal region has four primary groups of nuclei. The septum pellucidum is a midline, paramedian structure that separates the lateral ventricles. Lesions such as interhemispheric lipoma and interhemispheric cyst can coexist.
MRI should be used to rule out associated intracranial or extracranial anomalies, such as cortical malformations, parenchymal lesions, and brain-stem or cerebellar abnormalities.
172.4) ( Chapter 34) is one of the most common congenital brain malformations suspected upon prenatal US by the presence of a colpocephalic configuration of the occipital horns with parallel orientation of the lateral ventricles, and absence of the septum pellucidum. 55,56Īgenesis/hypogenesis of the corpus callosum ( Fig. It increases in length, width, and thickness with gestational age. 31,54 The corpus callosum appears on midline sagittal T2-weighted images as a C-shaped hypointense structure at the upper margin of the cavum septi pellucidi. During fetal development, the septum pellucidum is filled with CSF and is referred to as the cavum septi pellucidi. The septum pellucidum is in close developmental association with the corpus callosum. The septum pellucidum is a thin vertical membrane walled off by the corpus callosum above and the fornix below, separating the frontal horns of the lateral ventricles ( Fig. Salomon, in Obstetric Imaging: Fetal Diagnosis and Care (Second Edition), 2018 Midline Structures However, if we do the same dissection anteriorly to the foramen of Monro, we will split the rostrum of the corpus callosum and reach the interhemispheric fissure above lamina terminalis.Īnne-Elodie Millischer. If we separate the two laminae that compose the septum pellucidum and continue inferiorly between the fornices, we will have access to the third ventricle. This difference has to be remembered when performing an interforniceal approach. Anterior to the foramen of Monro, the septum pellucidum is attached inferiorly to the rostrum of the corpus callosum, whereas posterior to the foramen of Monro the septum pellucidum is attached to the fornix. It is important to pay attention to the inferior attachment of the septum pellucidum. The septum pellucidum is attached superiorly to the body of the corpus callosum and anteriorly to the genu of the corpus callosum. The septum pellucidum separates the frontal horns and body of the ventricle in the midline. Antonio Cesar de Melo Mussi, Evandro Pinto da Luz de Oliveira, in Comprehensive Overview of Modern Surgical Approaches to Intrinsic Brain Tumors, 2019 Septum Pellucidum
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