It is a closed sac having two layers: the visceral layer (epicardium), immediately surrounding the heart, and the outer parietal layer, forming the sac, composed of strong fibrous tissue, the fibrous pericardium, lined with a serous membrane, the serous pericardium. Synonym(s): heart sac, theca cordis.
The right and left cavernous sinuses are interconnected by the anterior and posterior intercavernous sinuses. Tributaries of the cavernous sinus include the superior ophthalmic, superficial middle cerebral, and inferior cerebral veins and the sphenoparietal sinus.
Frontal- one sinus per side, located within the bone of the forehead above the level of the eyes and nasal bridge (figures 1 and 3). Sphenoid- one sinus per side, located behind the ethmoid sinuses; the sphenoid is not seen in a head-on view but is better appreciated looking at a side view (figure 3).