Lateral Ventricles

The cavities of the telencephalon are the lateral ventricles, of which there is one in each hemisphere. As the development of the hemispheres creates the frontal, temporal, and occipital lobes, the lateral ventricles are pulled along and thus acquire their definitive adult shape of a flattened C with a short tail. This shape is present by birth. The lateral ventricle consists of an anterior horn, a body, and posterior and inferior horns. The junction of the body with the posterior and inferior horns constitutes the atrium of the lateral ventricle. An especially large clump of choroid plexus, the glomus (or glomus choroideum), is found in the atrium. In adults and especially in elderly persons, the glomus may contain calcifications that are visible (as white spots) on radiographs or computed tomography (CT) scans. Shifts in the position of the glomus, usually accompanied by alterations in the volume or shape of the surrounding ventricle, may indicate some type of ongoing pathologic process or space-occupying lesion.

The elaborate shape of the lateral ventricle means that different structures border on different parts of this space. The anterior horn and body of the lateral ventricle are bordered medially by the septum pellucidum (at rostral levels) and by a bundle of fibers called the fornix (at caudal levels) and posteriorly (superiorly) by the corpus callosum. The floor of the body of the lateral ventricle is made up of the thalamus, and the caudate nucleus is characteristically found in the lateral wall of the lateral ventricle throughout its extent. In the temporal lobe, the inferior horn of the lateral ventricle contains the tail of the caudate nucleus in its lateral wall, the hippocampal formation in its medial wall, and a large group of cells (the amygdaloid complex) in its rostral end.

The openings between the lateral and third ventricles, the interventricular foramina, are located between the column of the fornix and the rostral and medial ends of the thalamus. There are two interventricular foramina, one opening from each lateral ventricle into the single midline third ventricle.