24A08: Exam Report

Describe the anatomy of the femoral vein as it relates to central venous cannulation.

22% of candidates passed this question.

Anatomical questions are best answered with a standard structure that details the location; the boundaries (anterior/posterior, superior/inferior, medial/lateral); a description of the contents of that area and layers; and the relevant surface anatomy.

For this question a description of the femoral triangle and boundaries, the origin and termination of femoral vein along with its tributaries, the relationship of the femoral vein to different structures in the triangle and information about femoral sheath and its contents was expected.

Marks were also awarded for detailing the surface anatomy of femoral vein relevant to cannulation.

This was an anatomy question as such details of femoral vein cannulation technique, complications and the risks associated with femoral venous access was not required.

Xi / 24A08: Anatomy of the femoral vein

Origin

  • Drains from popliteal vein
  • Lies in intermediate compartment of femoral sheath
  • Drains to external iliac vein (at inguinal ligament)→ common iliac vein → IVC

Course

  • Common femoral vein → proximal to confluence with deep femoral vein

Borders

Femoral triangle

  • Superior: Inguinal ligament
  • Lateral: Medial border of sartorius muscle
  • Medial: Lateral border of adductor longus muscle
  • Superficial: Skin, subcutaneous fat, superficial fascia, fascia lata
  • Deep: Muscular fascia of pectineus, psoas & iliacus muscles

Landmarks

  • Anterior superior iliac spine (ASIS)
  • Pubic ramus
  • Inguinal ligament
  • Femoral sheath

Laterally → Medially (NAVEL)

Relationships

  • Distally: vein lies posterolateral to superficial femoral artery
  • Proximally (apex of femoral triangle): vein lies posterior to artery
  • Base of femoral triangle (within femoral sheath): vein lies medial to artery
  • Femoral artery (midpoint between anterior superior iliac spine and pubic symphysis)
    • Femoral vein MEDIAL to pulsation 0.5-1cm

Tributaries

  • Greater saphenous vein
  • Deep femoral vein
  • Lateral circumflex femoral veins
  • Medial circumflex femoral veins

Structures Needle Passes Through (Superficial → Deep)

  • Skin
  • Subcutaneous tissue
  • Fascia (encloses femoral vessels)
  • Femoral vein
    • Medial: medial compartment of femoral sheath (femoral canal: lymph vessels, nodes, fatty tissue)
    • Lateral: fibrous septum separating intermediate compartment & lateral compartment (containing femoral artery) and further lateral (femoral nerve)
    • Posterior: posterior fascia & pectineus

Approach/Positioning

  • Slight external rotation of hip, palpate pulse, medial to arterial pulsation
  • Folded towel under ipsilateral buttock to slightly extend hip
  • Proceduralist on ipsilateral side of patient

Femoral Artery Course

  • Continuation of external iliac artery at level of inguinal ligament
  • Enters femoral triangle deep to midpoint of inguinal ligament, lateral to femoral vein
  • Passes through triangle, exits at apex, enters adductor canal (Hunter’s canal)
  • Exits adductor canal by passing through adductor hiatus in adductor magnus (at level of junction between middle and lower third of thigh) → becomes popliteal artery
  • Several branches
    • Profunda femoris: chief artery to thigh, arises from lateral aspect of femoral artery, 2-5cm below inguinal ligament
      • Perforating arteries: perforate adductor magnus → contributes to supply of muscles in medial & posterior thigh
      • Lateral femoral circumflex artery: supply lateral thigh muscles
      • Medial femoral circumflex artery: supply neck and head
    • Superficial epigastric
    • Superficial iliac circumflex
    • Superficial & deep external pudendal arteries
Diagram of the femoral triangle anatomy and structures.
Diagram of femoral artery branches.

Author: Novia Tan