College Answer

The femoral vein lies in the intermediate compartment of the femoral sheath.  It is usually accessed just inferior to the inguinal ligament.  The inguinal ligament can be defined by the surface anatomy of a line between the pubic tubercule and the anterior superior iliac spine. The mid point of the inguinal ligament is the site of the internal ring.   A needle inserted through the skin will pass through subcutaneous tissue, and the fascia of the femoral sheath before entering the femoral vein.  Posterior to the femoral vein is the posterior fascia of the femoral sheath, and the pectineus.   Lateral to the femoral vein is the fibrous septum separating the intermediate compartment of the femoral sheath from the lateral compartment (containing the femoral artery).  Further lateral to this is the femoral nerve.  Medial to the femoral vein is the medial compartment of the femoral sheath (femoral canal), which contains lymph vessels, nodes and fatty tissue.

Discussion

Judging by the collge answer,  "outline the anatomical structures relevant to the insertion of a femoral venous catheter" probably means "discuss the relations of the femoral vein in the usual site of femoral venous cannulation". In other words, the femoral triangle.

Basic points:

• The femoral vein lies within the femoral triangle:
  • The superior border is formed by the inguinal ligament.
  • The medial border is formed by the adductor longus.
  • The lateral border by the sartorius muscle.
  • The apex is formed by the sartorius crossing the adductor longus muscle.
  • The roof is composed of the skin, subcutaneous tissue, the cribriform fascia, and the fascia lata.
  • The floor is formed of underlying adductor longus, adductor brevis, pectineus, and iliopsoas muscles.
  • Lateral to the femoral vein is the femoral artery in a fibrous sheath
  • Medial to the femoral vein is the fatty lymphatic contents of the femoral sheath

Anatomical landmarks for localisation of the femoral vein:

• The inguinal ligament runs from the pubic tubercle medially to the anterior superior iliac spine laterally.
• The femoral artery pulse is roughly at the midpoint of the inguinal ligament
• The femoral vein is medial to the femoral pulse
• The puncture of the vessel should be approximately 1-1.5cm medially to the maximal femoral pulse, and approximately 1cm inferior to the inguinal ligament (thus the skin puncture should be slightly more inferior than this)