Intracranial ventricular anatomy

Imaging from a patient with incidental ventriculomegaly. No structural obstructing mass or other abnormality in the ventricular pathway (no cyst, stenosis or web).

Reconstructions provided from initial study with 1.5 T CISS (Siemens) and 3.0 T DRIVE (Philips) - both steady state free precession sequences. Later images compare these techniques - with higher resolution on the DRIVE, but also the presence of CSF flow voids.

Imaging from normal T1w sequences of the lateral ventricles and related structures.

Dedicated views from steady state free precession sequences.

The sagittal view demonstrates key third ventricular structures, described in a clockwise manner from the most anterior position on the sagittal reconstruction:

• supraoptic recess (into optic chiasm)

• infundibular recess

• tuber cinerum

• mamillary bodies

• midbrain

• cerebral aqueduct (of Sylvius) - with CSF flow void on DRIVE, not visible on CISS

• tectal plate

• posterior commissure

• pineal recess

• suprapineal recess

• tela choroidea, with dilation of the velum interpositum above it (including the internal cerebral veins)

• fornix

• massa intermedia (between the thalami)

• interventricular foramen (of Monro)

• anterior commissure

• lamina terminalis

The coronal view also shows many of these structures:

• infundibular recess (coronal)

• supraoptic recess (coronal)

• anterior commissure (coronal)

• interventricular foramen (of Monro) - coronal

• fornix

• massa intermedia

• posterior commissure

• septum pellucidum

• pineal recess

• tela choroidea

• choroid plexus (lateral ventricles)

• cerebral aqueduct

Sagittal and axial CISS reconstructions through the fourth ventricle.

Key structures include:

• floor of fourth ventricle (along the dorsal pontomedullary surface, also known as the rhomboid fossa)

• cerebral aqueduct (sagittal) / aqueduct of Sylvius (axial)

• roof of fourth ventricle (along the cerebellar vela)

• the peak of the ventricle in the cerebellum is the fastigium

• flow into cisterna magna via the median aperture (foramen of Magendie)

• flow into the cerebellopontine angle via the lateral apertures (foramina of Luschka)

• the most interior point is the obex, which passes into the central canal of the spinal cord

The choroid plexus in the lateral, third and fourth ventricles is highlighted in red. These arise from the tela choroidea and follow the choroid fissures in the lateral ventricles and along the roof of the fourth.

In the lateral ventricles, the plexus does not typically pass beyond the caudothalamic groove (orange arrows) - this is a useful point to identify in neonatal ultrasound.

The tuft of choroid tissue in the atria of the lateral ventricles is known as the glomus (

The plexus can extend through the lateral apertures of the fourth ventricle (Luschka), with tissue in the cerebellopontine angles.