Veins and Arteries

Venous System Overview

  • Veins return blood to the heart from the lower extremities.

  • They carry the same volume of blood as arteries but at a lower pressure.

  • Veins have valves to prevent backflow because venous pressure is lower and flow is more prone to reversal.

  • Veins are compressible and have thinner walls compared to arteries.

Major Venous Pathways and Junctions

  • The common iliac vein divides into the internal iliac vein and the external iliac vein.

  • Internal iliac vein: drains pelvic organs (the branch responsible for pelvic vascular drainage).

  • External iliac vein: continues toward the lower limb (eventual continuation into the femoral system).

Inferior Vena Caca (IVC) Anatomy and Position

  • The IVC returns blood from the lower body and ascends to the heart.

  • It begins at the junction of the common iliac veins.

  • Location:

    • Anterior to the spine

    • To the right of the aorta

    • Posterior to the liver (the IVC lies behind the liver; movement can be affected by deep inspiration)

  • The IVC is described as having four different sections.

  • Superior part: located near the diaphragm and heart—helps orient its position.

  • Hepatic veins: the largest tributary of the IVC; drain blood from the liver into the IVC and empty toward the diaphragm into the IVC.

  • Congenital anomalies at birth related to the IVC are possible but not common (imaging may visualize these).

  • Imaging considerations: IVC anomalies are typically assessed with imaging studies; some conditions (like tumor invasion) can be visualized.

IVC-Related Pathologies and Interventions

  • Tumor invasion of the IVC can occur and is a clinical consideration.

  • IVC filters: small metal devices placed by a vascular surgeon to catch blood clots before they reach the lungs (prevent pulmonary embolism).

  • These filters are typically placed to protect against embolic events originating from the lower venous system.

Hepatic Veins

  • Hepatic veins drain the liver and empty into the IVC.

  • They are the largest tributaries of the IVC.

  • Their drainage is directed toward the diaphragm and into the IVC.

Cross-Sectional Anatomy and Study Approach

  • The next slides provide cross-sectional views of the iliac veins to help you follow their course.

  • These cross-sections illustrate the relationships between the iliac veins and surrounding organs.

  • It’s helpful to study these images to understand where the veins lie relative to pelvic and abdominal organs.

Practical Takeaways and Connections

  • Vein characteristics: valves, thinner walls, compressibility