Left lymphatic vessels

Vasa lymphatica (sinistra)

Lymphatic & immuneLymphaticsWhole bodyLeft side

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What it is

The left lymphatic trunks: beaded, valved vessels no wider than a pencil lead that collect tissue fluid from the skin and muscles of the limbs. Superficial trunks run with the cephalic and basilic veins up the arm (via the cubital and axillary nodes) and with the great and small saphenous veins up the leg (via the popliteal and inguinal nodes); a deep trunk follows the femoral vessels, and the lumbar trunk carries everything from the iliac nodes up to the cisterna chyli, while the jugular, subclavian and bronchomediastinal trunks join the thoracic duct at the root of the neck.

Function

Return the 2-4 litres of fluid, protein and immune cells that leak out of the capillaries each day, carrying them through the lymph nodes and back to the veins.

Size

Collecting vessels 0.5-2 mm wide; the lumbar trunk about 3 mm; valves every 6-20 mm giving the beaded look

Clinical note

Each segment between two valves (a lymphangion) contracts 6-10 times a minute, helped by the muscle pump. Blocked or removed vessels cause lymphoedema; infection spreading along them shows as red streaks up the limb (lymphangitis).