Lamina affixa

The lamina affixa is the thin, ependyma-covered ventricular surface of the superior aspect of the thalamus, forming part of the floor of the central part (body) of the lateral ventricle.

Its lateral boundary is related to the caudato-thalamic groove, which separates the superior surface of the thalamus from the caudate nucleus. This groove contains the stria terminalis and thalamostriate vein, with the stria terminalis lying superficial to the vein.

Medially, the free margin of the lamina affixa approaches the choroidal fissure, where the tela choroidea and choroid plexus of the lateral ventricle are attached. The choroidal fissure lies between the fornix medially and the thalamus/lamina affixa laterally. Along this fissure, the choroid plexus projects into the lateral ventricle.