Corpus: Tela choroidea
from Latin: tela - fabric, cobweb
1. Definition
The tela choroidea is a thin layer of loose connective tissue formed by the pia mater in the area of the cerebral ventricles. The fine blood vessels that form the choroid plexus originate from this layer.
2. Anatomy
The tela choroidea arises during embryonic brain development through a duplication of the pia mater. It can be divided into different sections corresponding to the ventricles of the brain:
- Tela choroidea of the lateral ventricle
- Tela choroidea of the third ventricle
- Tela choroidea of the fourth ventricle
In the lateral ventricles, the tela choroidea forms a double-layered fold of pia mater and ependyma, creating the fissura choroidea. It is C-shaped and runs in the central part of the lateral ventricle between the fornix and thalamus, and in the inferior horn (lateral ventricular cornu) between the terminal stria and fimbria of the hippocampus. This is where the edges of the choroid plexus of the lateral ventricles are located.
In the third ventricle, the tela choroidea constitutes the ventricular roof. It is attached to the surface of the thalamus and merges laterally below the fornix into the tela choroidea of the lateral ventricles. Two vascularized folds protrude from above into the ventricular lumen, forming the choroid plexus of the third ventricle. If the tela choroidea is torn in this area, the tear-off line constitutes the so-called taenia thalami, which runs along the medullary stria of the thalamus.
The tela choroidea of the fourth ventricle is located between the cerebellum and the lower part of the ventricular roof. It is formed as a fold of pia mater by the attachment of the caudal surface of the cerebellum to the surface of the hindbrain.