Superficial lymphatic vessel

Superficial lymphatic vessels are thin-walled channels located in the subcutaneous tissue, running alongside superficial veins. Their primary function is to collect lymph from the skin and superficial fascia and transport it to regional lymph nodes, where it enters deeper lymphatic pathways.

Location and Pathways: Superficial lymphatic vessels are found within the dermis and subcutaneous tissue. They closely follow the course of superficial veins.

• Upper limb: Drain into the axillary lymph nodes.

• Lower limb: Drain into the popliteal, femoral, and inguinal lymph nodes.

• Head and neck: Drain into the cervical lymph nodes.

Structure: Superficial lymphatic vessels originate from converging lymphatic capillaries. Their endothelial lining, formed by overlapping cells, functions as one-way valves that allow interstitial fluid to enter while preventing backflow. These vessels contain valves to maintain forward flow and have thinner walls with less smooth muscle than deep lymphatic vessels.

Functions:

• Drainage: Return interstitial fluid from the skin and superficial tissues to the lymphatic system.

• Immune role: Transport antigens, dendritic cells, and lymphocytes to lymph nodes for immune surveillance.

• Integration: Connect with deep lymphatic vessels, which then merge into larger lymphatic trunks and ducts to re-enter the venous circulation.

Clinical Relevance:

• Infections: The spread of skin infections (e.g., cellulitis) often follows superficial lymphatic pathways.

• Lymphangitis: Inflammation of superficial lymphatic vessels appears as red streaks on the skin.

• Cancer metastasis: Skin cancers (such as melanoma) and breast cancer frequently spread first through superficial lymphatics to regional lymph nodes.

• Surgical importance: Mapping superficial lymphatic drainage is essential for accurate sentinel lymph node biopsy.