It gives passage to an emissary vein that connects cavernous sinus with pterygoid venous plexus and a nerve known as 'Nervoulus sphenoidalis lateralis.' Accessory meningeal artery may pass through the foramen in 20% cases.

The other inferiorly based periosteal flap is partially and carefully elevated to avoid disruption of the mastoid emissary vein (Figure 2).

(2) There was a statistically significant difference in the incidence of dehiscent sigmoid plate (P = 0.000), lateral sinus stenosis (P = 0.014), high jugular bulb (P = 0.000), sigmoid sinus diverticulum (P = 0.000), jugular bulb diverticulum (P = 0.000), dehiscent jugular bulb (P = 0.000), and a large emissary vein (P = 0.006) between the symptomatic and asymptomatic sides.

The patency of the channel depends upon the condylar emissary vein that runs along its path.

The distal left sigmoid sinus and the internal jugular vein were occluded, and an emissary vein was identified draining off the left transverse sinus into the external jugular vein.

Of note, the posterior auricular vein also receives drainage from the sigmoid sinus via the mastoid emissary vein and this does pose a potential route for back flow if the pressure increases.

The FV gives passage to an emissary vein that connects the pterygoid venous plexus with the cavernous sinus (Aviles-Solis et al.).

CTA revealed two dehiscence of sigmoid sinus wall and a mastoid emissary vein on the right side.