Lateral ventricle

The lateral ventricle (ventriculus lateralis) is located in the thickness of the cerebral hemisphere. There are two lateral ventricles: the left (first), corresponding to the left hemisphere, and the right (second), located in the right hemisphere of the cerebrum. The cavity of the ventricle has a complex shape. This shape is due to the fact that the ventricle sections are located in all lobes of the hemisphere (except for the insula). The central part of the lateral ventricle corresponds to the parietal lobe of the cerebral hemisphere, the anterior (frontal) horn to the frontal lobe, the posterior (occipital) horn to the occipital lobe, and the inferior (temporal) horn to the temporal lobe.

The central part (pars centralis) of the lateral ventricle is a horizontally located slit-like space, limited from above by transversely running fibers of the corpus callosum. The bottom of the central part is represented by the body of the caudate nucleus, part of the dorsal surface of the thalamus and the terminal strip (stria terminalis), which separates these two formations from each other. The medial wall of the central part of the lateral ventricle is the body of the fornix. Between the body of the fornix above and the thalamus below is the vascular fissure (fissura choroidea), to which the choroid plexus of the lateral ventricle is adjacent from the side of the central part. Laterally, the roof and the bottom of the central part of the lateral ventricle are connected at an acute angle. In this regard, the lateral wall of the central part is, so to speak, absent.

The anterior (frontal) horn (cornu frontage, s. anterius) has the appearance of a wide slit, curved downwards and laterally. The medial wall of the anterior horn is the septum pellucidum. The lateral and partly the lower wall of the anterior horn are formed by the head of the caudate nucleus. The anterior, upper and lower walls of the anterior horn are limited by the fibers of the corpus callosum.

The inferior (temporal) horn (cornu temporale, s. inferius) is a cavity of the temporal lobe, which it penetrates quite deeply. The lateral wall and roof of the inferior horn of the lateral ventricle are formed by the white matter of the cerebral hemisphere. The tail of the caudate nucleus also projects into the roof. In the area of the bottom of the inferior horn, a triangular collateral eminence (eminentia collateralis) is noticeable, continuing from the posterior horn - a trace of the depression of parts of the cerebral hemisphere located in the depths of the collateral groove into the cavity of the inferior horn. The medial wall is formed by the hippocampus, which extends to the very anterior sections of the inferior horn and ends in a thickening. This thickening of the hippocampus is divided by small grooves into individual tubercles (seahorse toes, digitationes hippocampi - BNA). On the medial side, the hippocampus is fused with the fimbria hippocampi, which is a continuation of the crus of the fornix. The vascular plexus of the lateral ventricle is attached to this fimbria, descending here from the central part.

The posterior (occipital) horn (cornu occipitale, s. posterius) projects into the occipital lobe of the hemisphere. Its upper and lateral walls are formed by fibers of the corpus callosum, the lower and medial walls - by the protrusion of the white matter in the occipital lobe into the cavity of the posterior horn. Two protrusions are noticeable on the medial wall of the posterior horn. The upper one - the bulb of the posterior horn (bulbus cornu occipitalis) is represented by fibers of the corpus callosum on their way to the occipital lobe, which in this place bend around the parieto-occipital groove protruding into the hemisphere. The lower protrusion - the bird's spur (calcar avis) is formed by the indentation of the medulla located in the depth of the calcarine groove into the cavity of the posterior horn. On the lower wall of the posterior horn there is a slightly convex collateral triangle (trigonum collaterale) - a trace of the indentation of the substance of the cerebral hemisphere, located in the depths of the collateral groove, into the cavity of the ventricle.

In the central part and the inferior horn of the lateral ventricle is the choroid plexus of the lateral ventricle (plexus choroideus ventriculi lateralis). This venous plexus is attached to the choroid ribbon (taenia choroidea) below and to the fornix ribbon above. The choroid plexus continues into the inferior horn, where it is also attached to the fimbria of the hippocampus.

The choroid plexus of the lateral ventricle is formed by the invagination of the pia mater of the brain with the blood vessels contained in it into the ventricle through the choroidal fissure. The pia mater is covered on the ventricular side by an internal (epithelial) plate (the remainder of the medial wall of the first cerebral vesicle). In the anterior sections, the choroid plexus of the lateral ventricle connects with the choroid plexus of the third ventricle through the interventricular foramen (foramen interventriculare).

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