Chronic lower limb oedema.

Contrary to popular belief, little fluid is reabsorbed by the capillary and most of it is returned to the circulation via the lymphatic. Lymph drainage begins in thin-walled, superficial initial lymphatics with wide (14 nm) oblique intercellular junctions that function as flap valves. They freely allow passage of fluid and protein into the lymphatic but prevent back flow. The initial lymphatics unite to form collecting vessels which feed into afferent lymph trunks alongside major vascular bundles. These have muscular contractile walls and semilunar valves to direct lymph flow centrally. Approximately eight litres of fluid a day pass through the afferent lymphatics. The afferent lymphatics drain into lymph nodes, where approximately four litres of fluid are absorbed daily by the nodal microcirculation, the remainder passing on to the thoracic duct via efferent lymphatics1. The duct empties into the left subclavian vein at its junction with the jugular vein.