Lateral ventricles !

The lateral ventricles are two C-shaped fluid-filled cavities inside the halves of the brain; they hold cerebrospinal fluid and enlarge in hydrocephalus.

Official name: Lateral ventricle

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What it is

Two C-shaped fluid cavities inside the hemispheres.

What it does

Hold cerebrospinal fluid; they enlarge in hydrocephalus.

Key facts

Where: Inside each hemisphere (frontal, occipital, temporal horns)
Blood supply: Choroid plexus: anterior and posterior choroidal arteries
Function: CSF -> interventricular foramina -> third ventricle

Relations

Above: Corpus callosum, forming the roof of the frontal horn and body (and, as the tapetum, the roof and lateral wall of the occipital and temporal horns); in the roof of the temporal horn, the tail of the caudate nucleus and the stria terminalis
Medial: Septum pellucidum between the two frontal horns and bodies; the fornix along the lower medial wall of the body; on the medial wall of the occipital horn, the bulb (forceps major) above and the calcar avis (raised by the calcarine sulcus) below
Lateral: Head of the caudate nucleus bulging into the frontal horn; the optic radiation outside the temporal and occipital horns
Below: Floor of the body, lateral to medial: body of the caudate, the groove with the stria terminalis and thalamostriate vein, the thalamus, the choroid plexus and the fornix; floor of the temporal horn: the hippocampus with the fimbria, and the collateral eminence laterally
Contents: CSF, and the choroid plexus in the body, atrium and temporal horn

How to find it

Kocher point, the usual entry for a frontal horn catheter, lies about 11 cm behind the nasion and 3 cm from the midline (near the mid-pupillary line), in front of the coronal suture; the catheter is aimed toward the inner corner of the eye on that side and the front of the ear (some texts: 10–11 cm and 2.5–3 cm).

On imaging

Cranial ultrasound through the anterior fontanelle in babies; CT or MRI later. The Evans index (widest span of the frontal horns divided by the widest inner skull diameter) above 0.3 indicates enlarged ventricles. A calcified choroid plexus in the atrium is a common normal finding.

Common problems

Hydrocephalus: fluid builds up and the ventricles enlarge, raising pressure (headache, vomiting; in babies a growing head).

How it is diagnosed

Ultrasound in babies; CT or MRI.

Treatment

A shunt (a thin tube from the ventricle to the abdomen) or an endoscopic opening (third ventriculostomy).

Clinical notes

Ventriculoperitoneal shunt: a catheter in the frontal or occipital horn drains CSF through a valve under the skin into the abdomen; blockage, infection and overdrainage are its problems
External ventricular drain: placed through Kocher point into the frontal horn in emergencies
Preterm babies bleed from the germinal matrix next to the caudate head, and the blood can fill the ventricles
In normal-pressure hydrocephalus, improved walking after removing CSF by lumbar puncture supports a shunt

Anatomical variants

Mild asymmetry between the two lateral ventricles is common and usually of no significance
Cavum septi pellucidi: a fluid space between the two leaves of the septum pellucidum; normal in the fetus and newborn, it persists into adult life in some people, at times extending backward as a cavum vergae
The occipital horns vary most in size and are often asymmetric, the left usually the larger; the calcar avis is occasionally absent

Development

Each one is the cavity of a side pouch of the telencephalon, a remnant of the hollow neural tube. As the hemisphere grows forward, up, back and then down around the insula, the cavity is drawn into its C shape, ending in the temporal horn.

Memory aid

Normal-pressure hydrocephalus: 'wet, wobbly and wacky' (incontinence, gait, dementia).

Test yourself

Think of the answer, then tap the question to see it.

What are the parts of each lateral ventricle, and how does it drain?

Frontal horn, body, atrium, occipital horn and temporal horn; it drains into the third ventricle through an interventricular foramen (of Monro).

Why are ventricular catheters aimed at the frontal horn of the lateral ventricle?

The frontal and occipital horns have no choroid plexus; the frontal horn is reached through Kocher point.

What is the triad of normal-pressure hydrocephalus?

Gait trouble, urinary incontinence and dementia with large ventricles; described by the Colombian neurosurgeon Salomón Hakim (Hakim–Adams syndrome).

What value of the Evans index indicates enlarged lateral ventricles?

Above 0.3: the widest span of the frontal horns divided by the widest inner skull diameter.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): ventriculus lateralis TA2 5639
Official Spanish (DeCS): Ventrículos Laterales DeCS D020547
English (TA2): Lateral ventricle

Sources: Terminologia Anatomica (TA2); DeCS; Neuroanatomy, Ventricular System; Anatomy of the Human Body (20th ed.): Development of the Nervous System (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; 13.1 The Embryologic Perspective (OpenStax (Rice University), 2022) · adapted, CC BY 4.0; Tratado de anatomía humana (9.ª ed.), tomo II, Libro V, cap. VI: Cerebro (configuración exterior e interior, ventrículos, formaciones coroideas, epífisis).

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Representative model, for educational purposes only.

Lateral ventricles highlighted on the Durgical 3D model