Superficial Inguinal Nodes

The superficial inguinal lymph nodes are a group of lymph nodes located in the superficial fascia of the upper thigh, just inferior to the inguinal ligament. These nodes form part of the peripheral lymphatic system and are responsible for draining the skin and superficial tissues of the lower limb, perineum, external genitalia, and lower abdominal wall. They are clinically important due to their accessibility and involvement in infections and malignancies affecting these regions.

Structure

The superficial inguinal nodes are numerous (typically 10–20) and oval in shape. They are embedded in the superficial fascia, just beneath the skin and fatty layer of the groin. These nodes are divided into two main groups based on their orientation relative to the inguinal ligament and great saphenous vein.

Subgroups

• Horizontal group: Runs parallel to the inguinal ligament; drains lower abdominal wall, external genitalia (excluding glans), and perineum
• Vertical group: Oriented along the terminal portion of the great saphenous vein; drains most of the superficial lower limb

Location

The superficial inguinal nodes lie within the femoral triangle in the upper thigh. They are located in the subcutaneous tissue superficial to the fascia lata and inferior to the inguinal ligament.

Function

• Drainage regions:
  • Lower anterior abdominal wall (below umbilicus)
  • Buttock skin and lateral gluteal region
  • External genitalia (excluding glans penis/clitoris)
  • Perineal skin, anal canal (below pectinate line)
  • Lower limb (via vertical group)
• Immune function: Filters lymph for pathogens and tumor cells; facilitates immune responses
• Efferent drainage: Lymph from superficial nodes drains into deep inguinal nodes, and then to external iliac lymph nodes

Clinical Significance

• Lymphadenopathy: Easily palpable and often enlarged in infections, sexually transmitted diseases, or cancers of the lower limb and genitalia
• Diagnostic importance: First-line indicator in evaluating inflammatory and neoplastic conditions of the perineum and lower extremities
• Subinguinal subgroup: Term sometimes used to describe the portion of the vertical group closely associated with the saphenofemoral junction