The lymphatic system is a vast network of vessels that functions to return excess fluid from the interstitial space to the blood stream. 1 Excess interstitial fluid is drained by lymphatic capillaries, which are composed of a single layer of lymphatic endothelial cells that overlap with each other. The overlapping cells are thought to act as primary valves allowing flow of interstitial fluid into lymphatic vessels but limiting outflow. [2][3][4] Lymph then flows from these capillaries into collecting lymphatics 5 which have a layer of lymphatic muscle cells (LMCs) that work to transport lymph through rhythmic contraction. 6,7 This intrinsic force from LMCs occurs in conjunction with extrinsic compressive force from surrounding tissue to propel lymph through the lymphatic system. 6,8 A secondary system of intraluminal valves within the lymphatic collecting ducts themselves prevents backflow of lymphatic fluid toward the capillaries. 6,8,9 Lymph then travels through lymph nodes into post-nodal lymphatic ducts which converge into either the thoracic duct or the right lymphatic duct; these are classically described as emptying into the junction of the subclavian veins and internal jugular veins on the left and right side, respectively. 9,10 These connections are the body's two major anatomic lymphovenous shunts, a term which refers to the anastomoses, be it natural or surgical, between the lymphatic system and the venous system. 11
| ANATOMIC ALLY NORMAL LYMPHOVENOUS S HUNTS
| Thoracic duct and right lymphatic ductThe natural anastomosis between the thoracic duct and the subclavian vein represents a well-known anatomic lymphovenous shunt. 12 The thoracic duct (TD) most commonly originates from the cisterna