Venous distribution of superficial cervical region in rhesus (Macaca mulatta) monkey.

The superficial veins of the cervical region in over 50 Macaca mulatta monkeys were studied. We found, in addition to the external jugular vein, another major vein, which we have termed jugular accessory. It is comparable in size and runs ventral to the external jugular vein. It commenced at the angle of the mouth, ran in a groove on the dorsal aspect of the submandibular gland, and descended on the surface of the sternocleidomastoid muscle where it was connected to the external jugular vein by a short transverse twig. It then descended toward the clavicle, crossed it ventrally, and immediately joined the cephalic vein. The resultant common vein pierced the thoracic wall between the clavicle and first rib and joined the external jugular and axillary veins, producing the subclavian vein. It was the jugular accessory and the external jugular, being connected as described, that formed an "H"-shaped system.