Subinguinal Lymph Nodes

The term "subinguinal lymph nodes" typically refers to a subset of the superficial inguinal lymph nodes, particularly the nodes located directly inferior to the inguinal ligament. They include both horizontal and vertical chains, and are involved in lymphatic drainage from the lower abdominal wall, external genitalia, perineum, and superficial regions of the lower limb. Though not a distinct anatomical group, the designation “subinguinal” is often used clinically to describe their position beneath the inguinal ligament in the superficial fascia of the groin.

Structure

Subinguinal lymph nodes are part of the broader superficial inguinal node group and are embedded in the fatty layer of superficial fascia. They are organized into:

• Horizontal group: Parallel to the inguinal ligament

• Vertical group: Along the terminal part of the great saphenous vein

These nodes are encapsulated, contain lymphoid follicles, and serve as the first line of immune surveillance for superficial structures in the lower body.

Location

Subinguinal nodes lie within the femoral triangle, beneath the inguinal ligament, in the superficial fascia (Camper’s fascia). They are positioned over the femoral vessels but superficial to the fascia lata.

Group Landmark Location Horizontal chain Just inferior to the inguinal ligament, across the groin Vertical chain Runs inferomedially alongside great saphenous vein

Function

• Lymphatic drainage:

  • Skin of lower abdominal wall (below umbilicus)

  • External genitalia (excluding glans penis/clitoris)

  • Perineum and anal canal (below pectinate line)

  • Lower limb superficial tissues

• Immune defense: Site of antigen presentation and lymphocyte activation

• Drainage pathway: Efferent vessels pass to deep inguinal nodes, and then to external iliac nodes

Clinical Significance

• Visible/palpable swelling: Often the first site of detectable lymphadenopathy in infections or malignancies of the lower body

• Examined in: Cases of STIs, skin lesions, and cancers of vulva, penis, or anal canal