Mammary veins deserve special notice for Venous drainage of Udder. They form a venous circle at the base of the udder, which is drained chiefly by two pairs of vein.
- The external pudic vein in the cow is of large size and forms one of the mammary vein.
- The other veins of the mammary gland are subcutaneous abdominal and perineal veins. Of these, subcutaneous abdominal and external pudic veins are large and therefore form the principle veins of the gland. They arise from the rich venous plexus at the base of the mammary gland.
- The paired anterior mammary or milk vein (subcutaneous abdominal vein) is very large in animals of dairy breeds.
- It leaves the anterior border of the udder about 7 cm from the linea alba runs a flexuous course forwards along the floor of the abdomen, dips under the cutaneous muscle passes through the foramen in the rectus abdominis and joins the internal thoracic vein.
- The two subcutaneous veins are connected by a transverse anastomosis and each is connected behind with the middle mammary vein.
- The paired middle mammary vein (external pudic vein) is also large and ascends in the inguinal canal as a satellite of the artery and joins the external iliac vein.
- Both are connected behind by a transverse branch from which arises, a single posterior mammary vein (perineal vein), which runs medially upwards to the perineum and joins the internal pudic vein.
