The Lateral Ventricles: A Detailed Review of Anatomy, Development, and Anatomic Variations

Anatomy of the atrium of the left lateral ventricle. Coronal T1-weighted MR image from a healthy 21-year-old woman. OB indicates occipital bulb containing fibers of forceps major; CA, calcar avis; T, collateral trigone; CC, tapetum of the corpus callosum; solid arrow, calcarine sulcus; open arrow, collateral sulcus. Illustration adapted with permission from Gray.⁶⁵

Histologic sections of the telencephalon in the developing embryo from weeks 5 to 8. The lateral ventricles (L) arise as outpouchings from the telencephalon. Rapid growth of the corpus striatum (CS) shapes the floor of the lateral ventricles and narrows the foramina of Monro (F). The primitive choroid plexus (CP) comprises a large portion of the ventricular cavity by the eighth week. Also note that the lateral ventricles occupy a large majority of the cerebral hemisphere at 8 weeks. Images courtesy of Dr John Cork, PhD, Department of Cell Biology and Anatomy at Louisiana State University Health Sciences Center and the Virtual Human Embryo Project. Images used were the following: Carnegie Stage 17, section 410; Carnegie stage 18, section 302; Carnegie stage 20, section 131; Carnegie stage 23, section 50. https://www.ehd.org/virtual-human-embryo.

Coarctation of the frontal horn. Axial T2-weighted MR image from a 3-year-old boy showing coarctation of the left frontal horn with connatal cyst formation (black arrow).

Periventricular cysts. A, Coronal T2-weighted MR image from a 1-week-old girl with a history of germinal matrix hemorrhage demonstrating coarctation of the bilateral frontal horns with connatal cyst formation (asterisks). Note that these cysts are at the level of the superolateral angles of the lateral ventricle (open arrow). B, Coronal T2-weighted MR image from the same patient demonstrating subependymal cysts (black arrows) located near the caudothalamic groove below the level of the superolateral angles (open arrow). Additional connatal cysts are present (asterisks). C, Coronal T2-weighted MR image from a 1-month-old boy with a history of germinal matrix hemorrhage and peripartum hypoxia demonstrating small bilateral periventricular cysts (white arrows) located above the level of the superolateral angles (open arrow). This appearance is consistent with cystic periventricular leukomalacia.

Variations in lateral ventricular size and shape in a healthy 16-year-old girl. Axial T1-weighted MR images through the bodies of the lateral ventricles (A) and occipital horns (B) demonstrate a larger left lateral ventricle. Note the differences in morphology of the occipital horns. C, Coronal T1-weighted MR image through the frontal horns demonstrates relative enlargement of the left lateral ventricle.

Lateral ventricular asymmetry in a 56-year-old woman referred from a separate institution for the management of a suspected intraventricular mass. A, Axial T1-weighted MR images demonstrate asymmetric enlargement of the right lateral ventricle. There is mild bulging of the septum pellucidum (white arrow), which prompted careful evaluation of the lateral ventricular outflow. Coronal (B) and Axial (C) T2-weighted FLAIR images show no intraventricular mass but rather coaptation of the ependyma covering the caudate nucleus and fornix (black arrow). These imaging findings causes partial outflow obstruction and unilateral hydrocephalus. This remained stable on multiple subsequent follow-up MRIs and was favored to represent coarctation versus scar.

Cavum septi pellucidi and vergae. Axial T2-weighted MR image of a 67-year-old man demonstrating expansion of the cavum septi, consistent with cavum septi pellucidi (asterisk). There is extension posterior to the vertical plane of the columns of the fornix (not shown here) consistent with coexisting cavum vergae.