The diaphragma sellae consists of two horizontal leaves of dura mater on the sphenoid bone. It extends from the tuberculum sellae to the posterior clinoid processes and dorsum sellae and covers the sella turcica and pituitary gland within . It is the medial continuation of the superior roof of the cavernous sinus . It is deficient centrally where the infundibulum of the pituitary gland passes to join the inferior wall of the third ventricle. It does not contain a subarachnoid space.
- superiorly: optic chiasm
- inferiorly: pituitary gland in the sella turcica, anterior and posterior intercavernous sinuses within the layers of the diaphragma sellae
- defects of 5 mm or more in up to 40% (resulting in empty sella sign)
- constriction of the diaphragma sellae causing a "snowman appearance" of mass lesions extending into or from the pituitary fossa
- post contrast enhancement is a normal feature
- more easily appreciable on MRI sequences with long TR or short TE
- enhancement post contrast is a normal feature