Fornix, Lateral View

Description

Arcing beneath the corpus callosum, the fornix is presented in lateral (sagittal section) profile as a C-shaped white matter tract coursing posterior to anterior above the thalamus and along the roof of the third ventricle. Posteriorly, the fornix is continuous with the hippocampal formation via the fimbria and crura, then converges near the midline as the body of the fornix before turning inferiorly as the columns toward the hypothalamus. The anterior commissure and adjacent lamina terminalis region sit anteroinferior to the anterior fornix, while the pituitary stalk (infundibulum) and pituitary gland lie inferior to the hypothalamus. Brainstem structures descend posterior and inferior to the diencephalon, and the cerebellum occupies the posteroinferior fossa in partial view. This lateral cut clarifies why the fornix remains a practical landmark in limbic system teaching and in operative planning around the third ventricle. Injury to the fornix, classically during transcallosal or transcortical approaches to colloid cysts of the third ventricle or during placement of ventricular catheters near the foramen of Monro, can produce disproportionate anterograde memory impairment by interrupting hippocampal output to the mammillary bodies. Small structure, big consequences. Use this illustration when you need to explain hippocampus-fornix-hypothalamus connectivity in neuroanatomy blocks, to support figures in cognitive neuroscience or memory-disorder chapters, or to orient readers to deep midline targets in neurosurgical and neuroradiology atlases where sagittal relationships govern safe corridors. Anatomical accuracy verified by SciePro's Medical Advisory Board.