Path [edit]. The internal jugular vein is the continuation of the sigmoid sinus. It begins in the posterior compartment of the jugular foramen, at the base of the skull. It is somewhat dilated at its origin, and this dilatation is called the superior bulb.It also has a common trunk into which drains the anterior branch of the retromandibular vein, the facial vein, and the lingual vein.t begins in the posterior compartment of the jugular foramen, at the base of the skull. It is somewhat dilated at its origin, and this dilatation is called the superior bulb. It also has a common trunk into which drains the anterior branch of the retromandibular vein, the facial vein, and the lingual vein.