Velum interpositum
Updates to Article Attributes
The velum interpositum is a small membrane containing a potential space just above and anterior to the pineal gland which can become enlarged to form a cavum velum interpositum.
Gross anatomy
The velum interpositum is formed by an invagination of pia mater forming a triangular membrane the apex of which points anteriorly.
Boundaries
- superiorly: the columns of the fornices and hippocampal
commisurecommissure(psalterium(psalterium) reaching as far forward as the foramen of Monro - inferiorly: the internal cerebral veins and tela choroidea of the third ventricle
- inferolaterally: the thalamus
- posteriorly: the narrow base of the triangle abuts the splenium of the corpus callosum 1
It varies in shape from persion to person, sometimes interposed between the internal cerebral veins and splenium, and depending on whether or not there is a cavum vergae (in which case the columns of the fornices are displaced inferiorly, narrowing the velum interpositum).
When somewhat distended by fluid it forms a small triangular (in axial section) space and is referred to as a cavum velum interpositum. If larger and exterting mass effect it is known as a cavum velum interpositum cyst.
The space between the two leaves of pia contains the posterior medial choroidal arteries 2.
-<li>superiorly: the columns of the <a href="/articles/fornix">fornices </a>and <a href="/articles/hippocampal-commisure">hippocampal commisure</a> (psalterium) reaching as far forward as the <a href="/articles/interventricular-foramen-of-monro-1">foramen of Monro</a>- +<li>superiorly: the columns of the <a href="/articles/fornix-brain">fornices </a>and <a title="Hippocampal commissure" href="/articles/hippocampal-commissure">hippocampal commissure</a> (<a title="psalterium" href="/articles/psalterium">psalterium</a>) reaching as far forward as the <a href="/articles/interventricular-foramen-of-monro-1">foramen of Monro</a>