|The Lateral Ventricles
Dr. Muhammad Imran Qureshi
The Lateral Ventricles:
There are two lateral ventricles lying one within each cerebral hemisphere. Each lateral ventricle is a roughly “C” shaped cavity within a cerebral hemisphere. Each lateral ventricle wraps itself around the Thalamus, the Lentiform nucleus, and the Caudate nucleus. It is lined with ependyma and filled with cerebrospinal fluid. The capacity of each is about 7-10 ml.
The main parts of two ventricles are separated from each other by a partition extending between the corpus callosum and fornix, called Septum Pellucidum. The Septum Pellucidum is a thin vertical sheet of nervous tissue consisting of a mixture of grey and white matter, and covered on either side by the ependyma.
Each lateral ventricle communicates with the third ventricle through the interventricular foramen (of Monro). In the CNS most of the CSF is produced by the choroid plexuses of two lateral ventricles.
Each lateral ventricle consists of a central part which gives off three extensions called the anterior, posterior and inferior horns.
Parts of Lateral Ventricle:
For the purposes of description, each lateral ventricle is divided into 4 parts:
Central part or body lies mostly within the parietal lobe and extends from interventricular foramen in front to the Splenium of the Corpus callosum behind.
Anterior horn is the anterior extension from the central part into the frontal lobe and, lies in front of interventricular foramen and behind the posterior surface of the Genu of Corpus callosum,
Posterior horn is the backward extension from the central part into the occipital lobe towards the occipital pole, and
Inferior horn is the extension of the ventricle into the temporal lobe. It is considered as the direct continuation of the main ventricular cavity. It is the largest of the three horns. It begins where the central part and posterior horn meet and curves round the pulvinar of thalamus into the temporal lobe to end about 2.5 cm behind the temporal pole.
The Central Part:
The central part of the lateral ventricle is elongated anteroposteriorly. Anteriorly, at the level of the interventricular foramen, it becomes continuous with the anterior horn. Posteriorly, it reaches the Splenium of the Corpus callosum.
It is triangular in cross section and has a roof, a floor, and a medial wall. The roof and floor meet on the lateral side.
The roof is formed by the trunk of the Corpus callosum.
The medial wall is formed by the Septum Pellucidum and by the body of the Fornix.
It is common to the two lateral ventricles.
The floor is formed mainly by the superior surface of the Thalamus (medially), and by the Caudate nucleus (laterally).
Between these two structures there are the Thalamostriate vein (medially) and the Stria terminalis (laterally). There is a space between the fornix and the upper surface of the thalamus. This is the Choroid fissure.