[The jugular foramen, the inferior bulb of the jugular vein and their surgical approach].

Anatomical features of the sigmoid sinus and internal jugular vein and their connections are described. The jugular foramen is really only the opening of a bony canal between occipital and temporal bones, and is equivalent to a connective opening between the occipital vertebra and petrosal bone. The junction between the sigmoid sinus and internal jugular vein has the form and probably also the function of a siphon, but one in which the two arms are at right-angles. The jugular vein sinus has numerous vessels emptying into it, including some; condylar veins and inferior petrosal sinus, that are of high importance: valves are present at their orifices and the jugular sinus contains cords as in the cardiac cavities. The jugular vein sinus certainly plays a physiologic role in venous flow: a rigid-wall canal, the sigmoid sinus is followed by one with flexible, easily collapsible walls: the jugular vein. The latter is submitted to very high negative pressures that have to be compensated for by the sigmoido-jugular siphon in order to maintain cerebral vascular filling. Surgical approach to the jugular vein sinus is complicated by two factors: the facial nerve and hemorrhage. The facial nerve in its bony canal is situated immediately adjacent to the jugular sinus and must be displaced to reach the vein. The sinus is almost always approached for jugular glomus tumors, which are very hemorrhagic lesions. To prevent blood loss, the sigmoid sinus and then the external carotid are linked to the jugular vein.(ABSTRACT TRUNCATED AT 250 WORDS)