The facial vein originates from the medial canthal vein, travels posteriorly and inferiorly, passes through the superficial surface of the occlusal muscle, the inferior border of the mandible and the superficial surface of the submandibular gland sheath, and finally joins with the anterior branch of the posterior mandibular vein (also known as the retrofacial vein) below the angle of the mandible to form the common facial vein.
The facial vein is the main extracranial branch of the internal jugular vein. The facial vein collects venous blood from the soft tissues of the face. The facial vein communicates with the intracranial cavernous sinus through the medial canthal vein and the ophthalmic vein. The facial vein generally has no valves above the flat corners of the mouth.
When septic infection occurs on the face, especially in the triangle between the root of the nose and the corners of the mouth on both sides (clinically referred to as the triangle of danger), it is important not to squeeze, so as not to allow bacteria to enter the skull via the medial canthal vein and ophthalmic vein, causing intracranial infection.