sinus septum

si·nus sep·tum

a small fold forming the medial end of the valve of the inferior vena cava; it is developed from the dorsal wall of the embryonic sinus venosus.
References in periodicals archive ?
The cavity in the left frontal sinus was evaluated using 70-degree endoscope because of the defect in the frontal sinus septum, the internal part of the sinus was irrigated and aspirated.
A partial anterior septectomy was performed and extended superiorly to the interfrontal sinus septum that had been eroded by tumor.