Lateral ventricle

The lateral ventricles are paired, C-shaped cavities within the cerebral hemispheres. Each consists of a body and atrium, with three projections; the frontal, temporal and occipital horns, extending into the corresponding cerebral lobes. Each lateral ventricle has an estimated capacity of 7–10 mL and communicates with the third ventricle through the interventricular foramen of Monro.

Frontal horn

The frontal horn extends anteriorly from the foramen of Monro. Its roof and anterior wall are formed by the genu of the corpus callosum, its floor by the rostrum of the corpus callosum (and by the head of caudate nucleus), its lateral wall also by the head of the caudate nucleus, and the medial wall by the septum pellucidum and the column of the fornix.

Body

The body of lateral ventricle extends posteriorly from the foramen of Monro to the atrium. Its roof is formed by the body of the corpus callosum, its floor (and/or lateral wall) mainly by the thalamus and the body of caudate nucleus, and its medial wall by the septum pellucidum and body of the fornix.

Atrium, temporal, and occipital horns

The atrium is a triangular cavity where the body meets the temporal and occipital horns. The temporal horn, the longest and largest horn, extends anteriorly below the thalamus and terminates at the amygdala; its floor includes the hippocampus and collateral eminence. The occipital horn extends posteriorly and medially from the atrium into the occipital lobe and is variable in size.

Choroid plexus

The choroid plexus lies within the lateral ventricle along the choroidal fissure, a C-shaped cleft between the fornix and thalamus, and is an important source of cerebrospinal fluid.