Anatomy: Groin and Inguinal

Femoral Triangle

• See radiopaedia figures

Borders

• Roof: fascia lata (covers femoral sheath)
  • Fascia lata is continuous with external oblique aponeurosis superiorly[1]
• Floor: pectineus, iliopsoas, adductor longus muscles
• Superior: inguinal ligament (runs from anterior superior iliac spine to pubic tubercle)
  • Inguinal ligament is the portion of the external oblique aponeurosis which extends between the anterior superior iliac spine and the pubic tubercle as a thick band, folded inward[2]
• Lateral: medial border of sartorius muscle
• Medial: medial border of adductor longus muscle

Contents

Lateral to medial: NAVEL

• Nerve
• Artery
• Vein
• Empty space
  • Allows the veins and lymph vessels to distend to accommodate different levels of flow
• Lymph nodes

Left femoral triangle; source: Wikipedia

Nerves

• Femoral nerve
  • Lies deep to the iliacus fascia
  • Lateral to common femoral artery
  • Functions
    • Motor: innervates the pectineus, quadriceps femoris, and sartorius muscles
    • Sensory: anterior thigh
  • Should be preserved during inguinal dissection.
    • Some of the sensory branches, however, are commonly sacrificed in the regional node dissection.

Vasculature

• Posterior to fascia lata
• Common femoral artery
  • Continuation of external iliac artery
    • External iliac artery above inguinal ligament, common femoral artery below inguinal ligament
  • Gives off a branch called deep (profunda) femoral artery and continues as superficial femoral artery[3]
  • Blood supply to the skin of the inguinal region is from branches of the common femoral artery.
    • Complete inguinal dissection necessitates ligation of these branches.
      • Viability of the skin flaps raised during the dissection depends on anastomotic vessels in the superficial fatty layer of the Camper fascia
      • A transverse skin incision least compromises blood supply to the skin.
  • Medial to femoral nerve
  • Just medial to the midpoint of the inguinal ligament in the inguinal crease region[4]
• Common femoral vein
  • Deep femoral vein and Great saphenous vein (also known as long saphenous vein) empty into the common femoral vein
    • Great saphenous vein approaches common femoral vein medially
    • Deep femoral vein approaches common femoral vein laterally
  • Medial to common femoral artery
• Common femoral artery and common femoral vein are enclosed in femoral sheath[5]

Inguinal Lymph Nodes

• Classified as superficial vs. deep inguinal nodes
  • Fascia lata of the thigh separates the superficial and deep inguinal nodes
• Superficial inguinal nodes
  • Anatomic groups (5):
    1. Central nodes around the saphenofemoral junction
    2. Superolateral nodes around the superficial circumflex vein
    3. Inferolateral nodes around the lateral femoral cutaneous and superficial circumflex veins
    4. Superomedial nodes around the superficial external pudendal and superficial epigastric veins
    5. Inferomedial nodes around the greater saphenous vein
• Deep inguinal nodes
  • Fewer in number, compared to superficial inguinal nodes
  • Lie primarily medial to the femoral vein in the femoral canal
  • Most cephalad of the deep inguinal nodes is the Node of Cloquet
    • Node of Cloquet is located between the femoral vein and the lacunar ligament
      • Lacunar ligament connects the inguinal ligament to the pectineal ligament

Penile Lymphatics

• Superficial lymphatic system
  • Drains the prepuce and skin of the penile shaft
  • Empties into the right and left superficial inguinal nodes
• Deep lymphatic system
  • Drains the glans penis
  • Empties into the superficial inguinal nodes and the deep inguinal nodes
• Primary site of metastatic spread of penile carcinoma occurs via the regional lymphatic system, first to the inguinal lymph node chain and then to the iliac and pelvic lymph nodes.
  • Presence and extent of regional LN metastases is the single most important prognostic factor in determining the long-term survival of patients with penile cancer
    • If cancer has spread to the pelvic nodes, long-term survival is < 10%
• Inguinal metastatic spread can be unilateral or bilateral, and crossover drainage from the right to left groin or vice versa can also occur.
  • Metastatic spread from the inguinal lymph nodes to the contralateral pelvis or from the right to left pelvis has never been reported.
  • Skip lesions with direct lymphatic drainage from penile tumors to the pelvic lymph nodes has never been reported. .
  • Further spread from the true pelvis to the retroperitoneal lymph nodes is beyond the regional drainage system of the penis and represents systemic metastatic disease