Tela choroidea

Tela choroidea is a fold of the pia mater that contains a vascularized core. It lies in apposition with the ependymal lining of the ventricles. When the tela choroidea extends into the ventricles, it is enveloped by the ependyma, forming the choroid plexus. The choroid plexus, containing cuboidal ependymal cells, produces cerebrospinal fluid in the brain.

The tela choroidea and the choroid plexus are present in the lateral, third, and fourth ventricles of the brain. In the third ventricle, the tela choroidea extends from the roof, forming choroid plexuses that hang into the cavity of third ventricle on either side of the midline.

The same tela choroidea on the roof of the third ventricle extends laterally through the choroid fissure and passes through the interventricular foramen of Monroe. Doing so, it enters the lateral ventricles on both sides, forming the choroid plexus of the lateral ventricles. The tela choroidea also enters into the temporal horn of lateral ventricle by infringing into the ventricular cavity through the lower part of the choroid fissure between the stria terminalis and fimbria of hippocampus.

For the fourth ventricle, the tela choroidea extends between the anteroinferior cerebellum, and the back of the medulla and fourth ventricle. Here, the tela choroidea enters the cavity of the fourth ventricle, surrounded by the ependyma, and forms the choroid plexus.

The arterial supply for the vascular core of the tela choroidea in the fourth ventricle comes from the posterior and anterior inferior cerebellar arteries (mainly PICA). While, the anterior and posterior choroidal branches of the internal carotid and posterior cerebral arteries supply the third and lateral ventricles, respectively.