A lymph trunk is a collection of lymph vessels that exit from the lymph nodes in specific areas of the body and service specific organs or limbs. The lymph trunks circulate the body’s lymph — a fluid that carries white blood cells — throughout the body, sharing a common capillary system with the cardiac system. There are several lymph trunks, named after the regions of the body they circulate within. The lymph branches off to other nodes to fight off infections from foreign pathogens and disease microbes. The lymph collected along these trunks is then deposited in one of two lymph ducts, before being reintroduced to the bloodstream by means of the subclavian veins.
The lymph nodes are manufacturers of white blood cells, also known as lymphocytes. These white blood cells are suspended within the milky-white colored lymph in the nodes and along the lymph vessels. These lymphocytes seek out foreign pathogens, bacteria that may have entered tissues through injuries, or disease microbes. The debris from these curbed infections and debris from dead cells in surrounding tissues travels through the lymph to its lymph trunk. As the debris in the lymph moves along a lymph trunk region and becomes reintroduced into the blood, it is eventually eliminated when blood filters through the kidneys.
The tissues surrounding the lymph nodes are also drained of excess fluids that may be in overabundance within tissues. These excess fluids travel along with the lymph and are transferred into the bloodstream through the subclavian veins; they are filtered out by the kidneys. In this manner, the body keeps fluid levels within the tissues balanced. When a lymph node itself becomes swollen with too much fluid or infection and it cannot drain it, this is a signal of a serious problem. The condition can be a first sign of cancer hindering a lymph node’s proper functioning.
When disease is suspected, swelling of the nodes along a specific lymph trunk can point doctors toward areas of the body to be tested. Swelling of nodes that are no longer draining fluids normally can result in blockages. Blockages from abnormal cell growths may be cancerous or show precancerous cell changes; for instance, the swelling of nodes in the bronchomediastinal lymph trunk can be a sign of either breast or lung cancer. Swollen nodes along the intestinal lymph trunk can be possible rectum or colon cancer. As the first line of defense in the body’s immune system, nodes are often impacted by any cancers that develop locally.