Lymphatics of abdomen and pelvis

Abdomen and pelvis drainage

Lymph from abdominal organs reaches the lumbar (right, left) and intestinal lymphatic trunks bypassing via relay lymph nodes surrounding the great abdominal vessels. These trunks unite at the cisterna chyli, forming the thoracic (left lymphatic) duct. This major lymphatic vessel empties into the venous circulatory system at the junction between the left subclavian and internal jugular veins. Lymphatic drainage of the pelvis closely resembles the abdomen. Lymph from the pelvic viscera reaches the common iliac lymph nodes bypassing via relay nodes (external iliac, internal iliac, sacral) located in the vicinity of the great pelvic blood vessels. The lumbar lymphatic trunks subsequently collect the lymph from the common iliac lymph nodes. 

Abdominal wall

The anterior abdominal wall consists of two lymphatic drainage systems:

• A superficial system which drains the skin and subcutis, and 
• A deep system which primarily drains the musculature and bones. 

The superficial system is divided into two territories by a horizontal, imaginary plane passing through the umbilicus (transumbilical plane). The majority of the lymph in the supraumbilical territory is drained by lymphatic vessels which empty into the anterior, or pectoral axillary lymph nodes, while a small portion ends up into the parasternal lymph nodes. In turn, lymphatic vessels found in the infraumbilical territory follow the superficial epigastric vessels and drain into the superficial inguinal lymph nodes.

In contrast, the lymphatic vessels of the deep system follow the course of some slightly deeper vessels, and follow three primary pathways:

• The superior epigastric pathway which follows the superior epigastric artery and drains into the parasternal nodes.
• The inferior epigastric pathway which follows the inferior epigastric artery and drains into the external iliac nodes.
• The intercostal pathway which follows in the inferior intercostal and subcostal arteries to the posterior mediastinal lymph nodes.

The lymphatic drainage of the posterior abdominal wall follows a similar pattern, with both superficial and deep lymphatic networks draining this region. Superficial drainage is achieved in both the lumbar and iliac regions via lymphatic vessels which follow the superficial circumflex blood vessels. The deeper lymphatic vessels follow two primary drainage pathways:

• The lumbar pathway which follows the lumbar arteries and drains into the lateral aortic nodes  
• The iliac pathway which follows the deep circumflex iliac artery and drains into the external iliac nodes

Peritoneum

The peritoneum is a serous membrane that lines the abdominal wall and the majority of internal organs. 

Posterior to it one can find the retroperitoneal space, which houses the anatomical structures not lined by the visceral peritoneum (e.g. the kidneys, ascending/descending colon etc.). How is lymph drained from the retroperitoneum? The retroperitoneal, or lumbar lymph nodes are commonly located around the abdominal aorta and inferior vena cava, forming three distinct groups: left lumbar (para-aortic), right lumbar (para-caval), and intermediate lymph nodes. The latter group is situated between the two great abdominal vessels. 

The left lumbar, or para-aortic, lymph nodes are situated in the vicinity of the abdominal aorta. They are divided into several subgroups and drain parts of the gastrointestinal tract, the internal organs located on the left side of the abdomen, the left testis/ovary, as well as some deep tissues of the posterior abdominal wall. In contrast, the right lumbar, or para-caval, lymph nodes surround the inferior vena cava. They also consist of several sub-groups and drain parts of the gastrointestinal tract and other structures located mainly on the right-hand side of the abdomen(e.g. right kidney and adrenal gland), as well as the right gonad. It’s quite logical, right? If you remember that the aorta is located slightly to the left within the abdomen, while the inferior vena cava is more to the right, then learning becomes logical without the need of brute memorization.

Stomach

As you know, the peritoneum surrounds several internal organs, so let’s take them one at a time and to explore their lymphatic drainage. The stomach is an organ of the digestive system consisting of four parts and two curvatures, all of which are closely related to its lymphatic drainage. The cardia of the stomach is drained by the juxtacardial lymph nodes, the fundus by the short gastric nodes, the lesser and greater curvatures by the gastric and gastroomental lymph nodes, respectively, and the pyloric part by the pyloric lymph nodes (suprapyloric, retropyloric, subpyloric nodes). Subsequently, lymph from these nodes empties into the celiac lymph nodes (located around the celiac trunk), which then flows through the intestinal lymphatic trunk into the thoracic duct via the cisterna chyli. 

Find out more about the lymphatics of the stomach, liver and gallbladder with the study unit below. After that, take the custom quiz to consolidate your knowledge!

Small and large intestines

Moving further along the digestive system, we come across the small and large intestines. The small intestine is anchored to the abdominal by the mesentery, a key structure involved in its lymphatics. The mesentery contains an extensive lymphatic network of approximately 150 lymph nodes which are arranged into three stations:  

• the juxta-intestinal nodes (found along peripheral arterial arcades)
• the intermediate mesenteric nodes (along the jejunal and ileal arteries), and 
• (central) superior mesenteric nodes (along the length of the superior mesenteric artery). 

Lymph from the lacteal passes sequentially through these group of lymph nodes before finally ending up in the superior mesenteric lymph nodes. Lymph from the proximal duodenum flows through superior pancreaticoduodenal, pyloric, hepatic lymph nodes which drains to the celiac lymph nodes. The terminal ileum is also an exception because lymph follows the ileocolic artery towards the ileocolic lymph nodes. The lacteals of the small intestine are important for the transportation of fats and fat soluble vitamins.

The large intestine represents the last part of the gastrointestinal system and consists of several parts, each one with its own lymphatic drainage. 

In the end, the celiac and mesenteric lymph nodes, which drain the majority of the gastrointestinal tract, as you can see, flow into the intestinal lymphatic trunk. 

Find out more about the lymphatics of the small intestine with the study unit below. After that, take the custom quiz to consolidate your knowledge!

Liver and gallbladder

The liver and gallbladder are two accessory organs of the digestive system responsible for many important functions, for example, detoxification and fat emulsification. The lymphatics of the liver are separated into superficial and deep systems: 

• The superficial lymphatic network is located within the superficial fibrous capsule of the liver (Glisson’s capsule) and drains in four directions. Lymphatics from the posterior surface of the liver drain into celiac/superior mesenteric or posterior mediastinal lymph nodes. Lymphatics from the anterior surface of the liver drain into the hepatic lymph nodes located at the porta hepatis. Lymphatics from inferior surface also drain into the hepatic nodes, or directly to lumbar lymph nodes, whereas lymphatics from the superior surface drain into hepatic nodes or parasternal/pericardiac nodes. After passing through several relay stations along the way, lymph from these regions ultimately reaches the right lymphatic and thoracic ducts.
• The deep lymphatics of the liver mostly drain to the hepatic lymph nodes, which then follow the course of the hepatic artery to drain into the celiac lymph nodes. Additional lymph vessels also exit through the bare area of the liver and drain to the posterior mediastinal/right lumbar nodes. These also empty in the right lymphatic and thoracic ducts.

The lymphatics of superior aspect of the gallbladder drain to the cystic lymph nodes or directly to the hepatic lymph nodes, whereas the lymphatics of the inferior aspect drain into the cystic, posterior pancreaticoduodenal or preaortic lymph nodes. 

Pancreas

The pancreas is another accessory organ of the digestive system that also plays a crucial role in the endocrine system. It is both an exocrine gland that facilitates digestion and an endocrine gland that releases mainly insulin and glucagon. The tail of the pancreas is drained by lymphatic vessels that empty into the splenic lymph nodes located along the splenic artery. Lymph drained from the body of the pancreas is largely emptied into the superior and inferior pancreatic lymph nodes, while vessels draining the head primarily empty into pancreaticoduodenal lymph nodes. Lymph from these sets of lymph nodes is subsequently transported to the superior mesenteric or celiac lymph nodes.

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Spleen

The spleen has a very similar lymphatic drainage to the tail of the pancreas. Lymphatic vessels travel along the splenic artery and empty into the splenic lymph nodes. As you know, these flow into the celiac lymph nodes. 

Find out more about the lymphatics of the duodenum, pancreas and spleen with the study unit below. After that, put that knowledge to the test with our fully customizable quiz!

Kidneys

The kidneys are two retroperitoneal organs responsible for blood filtration and urine production. Their lymphatic drainage follows the course of the renal veins and ends in the para-caval (right lumbar) and para-aortic (left lumbar) lymph nodes. 

Sitting on top of the kidneys are the adrenal glands, two endocrine organs that can induce the ‘flight-or-fight’ response when facing danger. Their lymphatic vessels drain in the ipsilateral lumbar lymph nodes. 

Urinary bladder

The urine produced in the kidneys travels via the ureters to the urinary bladder, where it is finally stored until urination. The ureters descend from the renal pelvis of the kidney, transporting urine to the urinary bladder. When describing the lymphatics of the ureters, these can be divided into three parts; the superior third is drained by the lumbar lymph nodes, the middle third by the common iliac lymph nodes, while the inferior third by the internal and external iliac nodes.

Lymph from the urinary bladder reaches the internal and external iliac lymph nodes. The former drains mostly the neck and fundus of the urinary bladder. The urinary bladder is continued by the urethra, a tubular structure that transports urine to the external environment. The female urethra drains mostly to the internal iliac lymph node. However, the longer male urethra flows in two directions: the proximal part to the internal iliac lymph nodes and the distal part to the inguinal lymph nodes.

Learn more about the lymphatics of the urinary organs by checking the study unit and custom quiz below!

Reproductive organs

Reproduction is essential for the survival of the human species because it involves the generation of new offspring and passing on our genes to future generations. The male reproductive system consists of several anatomical parts, some of which are internal while others are external. They are outlined in the following table, together with their lymphatic drainage.  

The female reproductive system has similar functions to its male counterpart, however it is more complex due to the necessity of accommodating a developing fetus. It is also associated with an intricate hormonal menstrual cycle that induces significant physiological and local anatomical changes within the body. The lymphatics of each specific part are outlined below:

Learn more about the lymphatics of the male genitalia with the study unit below, and then quiz yourself to see how well you retained!