The retromandibular vein is a branch of the jugular veins. The jugular veins go up the neck and join with the facial vein, which drain blood from the face and return it to the heart for oxygenation. The retromandibular vein is formed at the joining of the maxillary vein and the superficial temporal vein in front of the ear.
The retromandibular vein divides into two branches, anterior and posterior. The anterior portion proceeds forward to the anterior facial vein, and together they join to form the common facial vein. The posterior joins the posterior auricular vein to become the external jugular.
Studies of cadavers have shown that in some cases, the retromandibular vein runs a slightly different course on the right and left sides of the face. This variation can make surgery involving the retromandibular vein and the facial nerves more challenging.