Is the femoral vein medial or lateral to the femoral artery?

Femoral Vein Position Relative to Femoral Artery

The femoral vein lies medial to the femoral artery only in the region immediately inferior to the inguinal ligament, and then abruptly runs posterior to the artery distal to the inguinal region. 1

Anatomical Relationship at Different Levels

• At the level immediately inferior to the inguinal ligament, the common femoral vein is positioned medial to the common femoral artery 1
• Distal to the inguinal region, the vein abruptly transitions to run posterior to the artery 1
• The common femoral vein joins the deep femoral vein to form the common femoral vein approximately 5-7 cm below the inguinal ligament 1

Clinical Significance

• Understanding this anatomical relationship is crucial for procedures involving femoral vessel access, including central venous catheterization and arterial cannulation 2
• In ultrasound-guided femoral vein cannulation, identifying the vein medial to the artery at the inguinal ligament level serves as an important landmark 2
• Variations in this anatomical relationship have been documented, with studies showing that in some cases the femoral artery may partially or completely overlap the femoral vein 3, 4

Anatomical Variations

• In some patients (approximately 12% of pediatric cases), the femoral vein may be completely or partially overlapped by the femoral artery 3
• CT evaluation has shown that in 65% of vessel pairs, a portion of the common femoral artery overlaps the common femoral vein in an anteroposterior plane 5
• Rare variations exist where the femoral artery crosses the vein just deep to the inguinal ligament, placing the femoral vein deep to the artery at the base of the femoral triangle 6

Practical Implications for Procedures

• For femoral vein access, the optimal puncture site is at the level of the inguinal ligament where the vein is medial to the artery 1
• Ultrasound guidance for femoral vein cannulation reduces the risk of arterial puncture by allowing direct visualization of the anatomical relationship 2
• Patient positioning can affect the relationship between vessels, with studies showing that the frog leg position may increase the diameter of the femoral vein but can also increase arterial overlap 4

Boundary Relationships

• The femoral vein serves as the lateral boundary of the femoral canal, which is important in understanding femoral hernia anatomy 7
• The medial boundary of the femoral canal is the lacunar ligament (Gimbernat's ligament) 7
• The anterior boundary of the femoral canal is the inguinal ligament 7

Remember that anatomical variations exist, and ultrasound guidance is recommended for procedures involving the femoral vessels to confirm the specific relationship in each patient 2, 3.