General characteristics and topography
During embryogenesis, the cavities of the brain vesicles transform into a system of communicating spaces: lateral ventricles, III ventricle, cerebral aqueduct, and IV ventricle. This entire system contains cerebrospinal fluid and connects with the central canal of the spinal cord.
The lateral ventricles are divided into the left (ventriculus lateralis sinister) and right (ventriculus lateralis dexter). Anatomically, each of them is divided into several parts that topographically correspond to specific lobes of the cerebral hemisphere. The ventricle comprises a central part and three horns extending from it: anterior, posterior, and inferior.
Anterior horn and central part
The anterior (frontal) horn — cornu frontale (anterius) — is located inside the frontal lobe. On a cross-section, its cavity has the shape of a triangle convex medially.
The walls of the anterior horn are formed by the following structures:
- Upper and anterior walls are formed by the frontal radiation and the genu of the corpus callosum.
- Lateral wall is represented by the head of the caudate nucleus.
- Medial wall is a thin lamina of the septum pellucidum (lamina septi pellucidi). The right and left laminae form the septum pellucidum itself (septum pellucidum), between the leaves of which lies a slit-like cavity (cavum septi pellucidi), visible when the corpus callosum is removed.
In the posterior part of the medial wall (between the column of the fornix and the thalamus) is the interventricular foramen (foramen interventriculare). It is through this foramen that the lateral ventricle drains fluid into the III ventricle (ventriculus tertius).
The central part — pars centralis — projects onto the parietal lobe and is the most extensive division. The medial boundary here is the body of the fornix (corpus fornicis), the floor is formed by the superior surface of the thalamus, and it is bounded above and laterally by the fibers of the corpus callosum. Posteriorly, this part continues into the posterior horn, and downward it descends into the inferior horn.
Posterior and inferior horns
The posterior (occipital) horn — cornu occipitale (posterius) — lies in the occipital lobe. It is a narrow cavity 1.2 to 2.0 cm long, having a triangular shape on a coronal section. The posterior horn has three walls:
- Superior (dorsal) — the most narrowed part.
- Lateral — has a convex shape.
- Medial — concave, features important anatomical landmarks: the bulb of the posterior horn (bulbus cornu occipitalis), formed by fibers of the corpus callosum, and the calcar avis (calcar avis), which corresponds to the deep calcarine sulcus of the hemisphere.
Note: The fibers of the corpus callosum forming the roof and lateral wall of the posterior horn form the so-called tapetum.
The inferior (temporal) horn — cornu temporale (inferius) — is located in the temporal lobe, shifted toward its medial surface. It is 3–4 cm long, arched downward, forward, and inward. Anteriorly, it ends blindly (without reaching the temporal pole), with the amygdaloid body (corpus amygdaloideum) adjacent to it in the region of the uncus.
Walls of the inferior horn:
- Lateral and superior — formed by fibers of the corpus callosum.
- Inferior — partially includes the collateral trigone (trigonum collaterale).
- Medial — formed by the hippocampus.
Choroid plexus and ependyma
The most important structure of the central part and inferior horn is the choroid plexus of the lateral ventricle — plexus choroideus ventriculi lateralis. It enters the cavity from the interventricular foramen, participates in the formation of the medial wall, and continues into the inferior horn. In the area of the collateral trigone, it forms a noticeable expansion — the choroid glomus (glomus choroideum). The plexus is fixed to the fimbria of the hippocampus by means of the taenia fornicis (tenia fornicis).
In addition, embryonic structures persist on the walls of the ventricle:
- The lamina affixa (lamina affixa) — a remnant of the telencephalic wall on the superior surface of the thalamus. Medially, it transitions into the taenia choroidea (tenia choroidea).
- The stria terminalis (stria terminalis) — runs lateral to the lamina affixa, strictly along the border of the thalamus and the caudate nucleus. Its fibers connect the amygdaloid body with the hypothalamic nuclei and the septum pellucidum.
Briefly: answers to topical questions
What forms the inferior wall (floor) of the anterior horn of the lateral ventricle?
The inferior wall (floor) of the anterior horn of the lateral ventricle is formed by the head of the caudate nucleus.
The anterior horn begins in the frontal lobe, curving downward and laterally. Its walls are formed by:
- Head of the caudate nucleus (caput nuclei caudati) — a thickened anterior part (gray elevation) forming the floor and lateral wall.
- Septum pellucidum (septum pellucidum) — forms the medial wall.
- Corpus callosum (corpus callosum) — its fibers form the superior and anterior walls.
Which structures form the walls of the inferior horn of the lateral ventricle?
The walls of the inferior horn of the lateral ventricle are formed by fibers of the corpus callosum, the caudate nucleus, the hippocampus, and other structures.
The walls are formed by:
- Tapetum (tapetum) — fibers of the corpus callosum forming the lateral and upper lateral walls.
- Tail of the caudate nucleus (cauda nuclei caudati) — curves onto the superior wall from the medial side.
- Hippocampus (hippocampus) — forms the medial wall (an elevation along it).
- Choroid plexus of the lateral ventricle (plexus choroideus ventriculi lateralis) — participates in the formation of the medial wall.
- Collateral trigone (trigonum collaterale) — partially forms the inferior wall.
To remember the projection of the horns onto the brain lobes, use the mnemonic: "Front = Anterior, Back = Posterior, Down = Inferior." (Anterior — frontal, Posterior — occipital, Inferior — temporal).
Class and exam questions
Where is the interventricular foramen located?
It is located in the posterior part of the medial wall of the anterior horn, between the anterior tubercle of the thalamus and the column of the fornix. It connects the lateral ventricle with the III ventricle.
What forms the medial wall of the posterior horn?
The medial wall is formed by two prominences: the bulb of the posterior horn (fibers of the corpus callosum) and the calcar avis (impression of the calcarine sulcus).
Which part of the lateral ventricle is the longest?
The most extensive part is the central part (pars centralis), located in the parietal lobe.
Where is the choroid plexus (glomus choroideum) formed?
The choroid glomus is an expansion of the choroid plexus and is located in the inferior horn, in the region of the collateral trigone.
What else to study on this topic
- Topography and functions of the amygdaloid body (corpus amygdaloideum)
- Anatomy of the fornix and its parts
- Structure and functions of the hippocampus
- Caudate nucleus: head, body, and tail
- Mechanism of cerebrospinal fluid circulation
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