Updated: Mar 7
For as long as I have been teaching about the lymphatic system (30+ years), the topic that students seem to struggle with most at the beginning, is locating the lymph pathways of the body. Part of the problem is the material we learn from in text books is usually 2D, and we are left to piece together our own 3D interpretation.
When we learn in the classroom we have the opportunity to engage via kinaesthetic learning, locating structures on each other and integrating the new information to our personal framework of the human body. But with the Dr Vodder basic theory going online, we are dependant even more than ever on those 2D images to help us understand the layout of the system.
This post offers a brief review of the lymph pathways and a visualisation to imagine your own lymphatic system.
Beginning at the most proximal part of the system, processed lymph is delivered to the sub-clavian veins by the thoracic duct on the left, and the right lymphatic duct.
Ducts empty into veins
Every duct has one or more trunks which are the portion of the collector vessels between the last lymph node and the lymphatic duct.
Trunks empty into ducts
The thoracic- and right lymphatic ducts each have three trunks in the upper thoracic cavity, the jugular trunk receiving lymph from the head & neck on that siude, the subclavian trunk delivering lymph from the axillas, and the broncho-mediastinal trunk from the thoracic cavity.
The cysterna chyli is the beginning of the thoracic duct and receives the lymph from the entire lower body via three trunks in the abdominal cavity, the right and left lumbar trunks and the intestinal trunk which delivers the chylous lymph from the small intestine. The thoracic duct also receives lymph from the posterior intercostal pathways via several intercostal trunks.
Ducts & trunks are collector vessels in the deep system.
The anatomical divider between the superficial and deep lymphatic stems is the deep fascia, the tough elastic connective tissue under the fatty layer of the skin and surrounding all muscles and visceral organs. Lymph vessels in the deep system are inside the peri-vascular sheath with the veins and arteries.
The superficial lymphatic system protects the body from invasion and maintains a slightly sub-atmospheric pressure in the superficial compartment by collecting fluid and invading microbes via the dense initial lymphatic plexus located only millimetres under the skin.
Lymph formed in the superficial system is transported by collector vessels located above the deep fascia to superficial lymph nodes, also located above the deep fascia.
To map the superficial lymph pathways, we use the concept of watersheds in a geographical landscape. In the same way that a crest forms an imaginary dividing line that separates the rain falling on one side or the other of a range of hills, the watersheds are imaginary lines dividing the superficial lymphatic system into the six main regional lymph node basins, one on each side of the neck, and in the axillary and inguinal regions.
Lymph flows from superficial to deep.
The lymph node basins have both superficial and deep lymph nodes and this is where most of the lymph collected in the superficial system passes into the deep system whereafter the lymph pathways follow that of the veins.
Lymph nodes are usually named for adjacent structures, e.g. parotid lymph nodes and sacro-illiac lymph nodes. Collector vessels link all lymph nodes along the lymph vessel pathway.
Visualising the lymphatic system.
Over the years I have tried to help clients understand their lymphatic system and whatever damage it has sustained. Since most lymphatic pathologies are irreversible, people affected by chronic oedema are faced with lifelong self-management, so it's important that they understand how their system works. I frequently use bathtubs, vacuum cleaners and hand pumps in my analogies, and have written other #TalkingLymph posts on the structure and function of the lymph vessels system.
Here is a free guided visualisation of your lymph system from within.