Lecture 8: Veins of the Systemic Circulation

Overview

• Veins drain blood from the body and return it to the right side of the heart.
• Deep veins resemble arteries; superficial veins are just beneath the skin, serving as blood reservoirs.
• All venous blood drains into the superior vena cava, inferior vena cava, or coronary sinus.

Major Veins and Drainage Pathways

Superior Vena Cava System

• Brachiocephalic Vein

  • Splits into internal jugular and right subclavian.
  • Right subclavian gives rise to vertebral and external jugular.

• Jugulars vs. Carotids Mnemonic:

  • Jugulars: External Jugular, Vertebral, Internal Jugular (EVI)
  • Carotids: Vertebral, Internal, External (VIE)

• Drainage to Superior Vena Cava

  • External and internal jugulars drain head and neck.
  • Internal jugular receives blood from the dorsal venous sinuses.

Vein Pathways of the Arm

• Dorsal Pathway:

  • Dorsal digital → dorsal metacarpal → dorsal venous network → right accessory cephalic → right cephalic & basilic → subclavian/brachial → axillary → subclavian

• Palmar Pathway:

  • Right palmar digital → right palmar venous plexus → right median antebrachial → basilic & cubital → palmar metacarpal → palmar venous arch → radial & ulnar → brachial → axillary → subclavian → brachiocephalic → superior vena cava

Abdominal and Thoracic Vein System

• Azygos System

  • Subcostal and ascending lumbar fuse to form azygos → superior vena cava
  • Accessory hemi-azygous and hemi-azygous → azygos → superior vena cava

• Left side drainage

  • Left subcostal and left ascending lumbar → hemi-azygous → azygos → superior vena cava

• Diaphragm Relation

  • Azygous and accessory hemi-azygous above diaphragm; hemi-azygous below diaphragm

• Hepatic Portal System

  • Blood from digestive system flows through hepatic portal system to liver, then via hepatic vein
  • Other veins: suprarenal, renal, gonadal

Lower Body Vein System

• Iliac and Femoral Veins

  • Common iliac → internal/external iliacs → external iliac becomes femoral
  • Femoral leads to popliteal, anterior and posterior tibial, fibular

• Superficial Veins

  • Great saphenous: longest vein, medial thigh
  • Small saphenous: lateral calf

Hepatic Portal System

• Blood from digestive system travels through capillaries to form hepatic portal vein
• Carries deoxygenated, nutrient-rich blood to liver for detoxification and processing

Venipuncture Sites

• Common sites: cubital fossa, dorsum of the hand, great saphenous vein (infants)

Goals for Lecture

• Describe venipuncture
• Trace blood flow from hands and feet back to the right atrium
• Label a diagram of major veins in the torso, head, and extremities