Circulatory Systems: Venous Return and Blood Vessels

Venous Return

• Returns blood to the heart, represented in blue, carries deoxygenated blood
• Have valves to ensure blood flows unidirectionally
• Have tributaries, smaller veins that combine to form a larger vein

Organization of Veins

• Organized into 3 groups:
  • Dural venous sinuses: large veins in the brain, empty into internal jugular veins
  • Deep veins: named similarly to arteries, located in the same location as arteries
  • Superficial veins: have new names, carry deoxygenated blood, have valves to prevent backflow

Veins of the Head and Neck

• Dural venous sinuses collect blood from the brain and empty into internal jugular veins
• Internal jugular veins drain the brain and empty into the subclavian vein
• External jugular veins drain the external head, neck, and face and empty into the subclavian vein
• Axillary vein drains the upper extremity and crosses the first rib to become the subclavian vein
• Subclavian vein drains into the right and left brachiocephalic veins, which give rise to the superior vena cava that empties into the right atrium of the heart

Veins of the Thorax

• Right and left common iliac veins travel with the CIA and give rise to the inferior vena cava
• Right common iliac vein can go through IVC or right ascending lumbar vein
• IVC passes through the diaphragm and empties into the right atrium
• SVC empties into the right atrium
• Right and left ascending lumbar veins travel next to the IVC
• Right ascending lumbar vein passes through the aortic hiatus and becomes the Azygos vein
• Azygos vein is a major vein that drains the thoracic cavity, unpaired, and drains to the SVC posteriorly

Veins of the Abdomen and Pelvis

• 4 pairs of lumbar veins that pass through the ascending lumbar veins in the IVC
• Right and left inferior phrenic vein drain to the inferior surface of the diaphragm
• Right and left hepatic veins drain the liver into the IVC
• Right and left renal veins drain blood from the ipsilateral kidney into the IVC
• Right suprarenal/adrenal vein drains into the right renal vein into IVC
• Left adrenal vein drains into the left renal vein, which empties into the IVC
• Right and left gonadal veins drain into the IVC or left renal vein

Hepatic Portal System

• Veins from the digestive tract, spleen, and pancreas do not empty directly into the IVC, but into the hepatic portal vein
• Hepatic portal vein collects blood from the digestive system and filters it through the liver before it empties into the IVC
• Right and left hepatic veins empty into the IVC
• Digestive system organs in the abdomen and pelvis drain into the hepatic portal vein that goes to the liver before it empties into the IVC

Veins of the Lower Extremity

• Right and left lower extremity drain blood into the right and left common iliac veins
• Common iliac veins are formed by the union of the external iliac vein and internal iliac vein or hypogastric vein
• Femoral vein empties into the external iliac vein, receiving from the popliteal vein
• Popliteal vein is formed by the union of anterior and posterior tibial veins
• Medial and plantar veins unite to empty into the posterior tibial vein, both receiving from the plantar venous arch
• Dorsal venous arch drains through 2 large superficial veins, the greater saphenous vein and lesser saphenous vein