Is There an Identifiable Intact Medial Wall of the Cavernous Sinus? Macro- and Microscopic Anatomical Study Using Sheet Plastination

BACKGROUND: The medial wall of the cavernous sinus is believed to play a significant role in determining the direction of growth of pituitary adenomas and in planning pituitary surgery. However, it remains unclear whether there is a dural wall between the pituitary gland and the cavernous sinus. OBJECTIVE: To identify and trace the membranelike structures medial to the cavernous sinus and around the pituitary gland and their relationships with surrounding structures. METHODS: Sixteen cadavers (7 females and 9 males; age range, 54-89 years; mean age, 77 years) were used in this study and prepared as 16 sets of transverse (5 sets), coronal (2 sets), and sagittal (9 sets) plastinated sections that were examined at both macro- and microscopic levels. RESULTS: The pituitary gland was fully enclosed in a fibrous capsule, but the components and thickness of the capsule varied on different aspects of the gland. The meningeal dural layer was sandwiched between the anterosuperior aspect of the gland capsule and the cavernous sinus. Posteroinferiorly, however, this dural layer disappeared as it fused with the capsule. A weblike loose fibrous network connected the capsule, carotid artery, venous plexus, and the dura of the middle cranial fossa. CONCLUSION: The medial wall of the cavernous sinus consists of both the meningeal dura and weblike loose fibrous network, which are located at the anterosuperior and posteroinferior aspects, respectively.