Lymph nodes of the thorax and abdomen
The lymph nodes are important structures of the lymphatic system. They are small, oval or kidney-shaped encapsulated centres of antigen presentation and lymphocyte activation, differentiation and proliferation. They vary in size from 0.1 to 2.5 cm in length. Lymph nodes generate mature, antigen-primed, B and T cells, and filter particles, including microbes, from the lymph by the action of numerous phagocytic macrophages.
A normal young adult body contains up to 450 lymph nodes, of which 60-70 are found in the head and neck, 100 in the thorax and as many as 250 in the abdomen and pelvis. Lymph nodes are particularly numerous in the neck, mediastinum, posterior abdominal wall, abdominal mesenteries, pelvis and proximal regions of the limbs (axillary and inguinal lymph nodes). By far the greatest number lie close to the viscera, especially in the abdominal mesenteries.
This article will describe the anatomy and function of the lymph nodes found in the torax and abdomen.
|Thoracic lymph nodes||Axillary, subcapsular, pectoral, parasternal, intercostal and diaphragmatic lymph nodes|
|Abdominal lymph nodes||
Deep group: preaortic, lateral aortic, retroaortic, celiac and mesenteric groups
- Thoracic lymph nodes
- Abdominal lymph nodes
- Clinical notes
Thoracic lymph nodes
The lymphatic drainage of the thorax may be broadly divided into parietal and visceral regions — the former being related to the thoracic wall, the latter in relation to the viscera.
Lymph vessels draining the superficial tissues of the thoracic wall drain into the axillary nodes, subscapular nodes, pectoral nodes, parasternal nodes and, to a lesser extent, the inferior deep cervical nodes.
Lymph vessels draining the deeper tissues of the thoracic wall end in the parasternal nodes, intercostal nodes, and diaphragmatic nodes.
Parasternal lymph nodes
This is also referred to as the internal thoracic nodes. There are 4 or 5 parasternal nodes along each internal thoracic artery, at the anterior ends of the intercostal spaces. They drain afferents from the breast, deeper structures of the supra-umbilical anterior abdominal wall, the superior hepatic surface (through a small group of nodes behind the xiphoid process), and deeper parts of the anterior thoracic wall.
Their efferents usually unite with those from the tracheobronchial and brachiocephalic nodes to form the bronchomediastinal trunk. The later may open, on either side, directly into the jugulo-subclavian junction. Alternatively, it may open into either the great vein near the junction or may join the right subclavian trunk or right lymphatic duct. It can also join the thoracic duct on the left.
Intercostal lymph nodes
The intercostal nodes occupy the intercostal spaces near the heads and necks of the ribs. They receive the deep lymph vessels from the posterolateral aspects of the chest and the breast, some of which are interrupted by small lateral intercostal nodes. Efferents of nodes in the lower 4 – 7 intercostal spaces unite into a trunk that descends to the abdominal confluence of lymph trunks or to the start of the thoracic duct. Efferents of nodes in the left upper spaces end in the thoracic duct, while those of the right upper spaces end in one of the right lymph trunks.
Diaphragmatic lymph nodes
This group of nodes is located on the thoracic surface of the diaphragm. They are arranged in anterior, lateral (right and left), and posterior groups.
- Anterior group: this group consists of two or three small nodes behind the base of the xiphoid process, draining the convex hepatic surface, and one or two nodes on each side near the junction of the 7th rib and cartilage, which receive anterior lymph vessels from the diaphragm. The anterior group drains to the parasternal nodes.
- Lateral group: the lateral group each contain two or three nodes, and lie close to the point where the phrenic nerves enter the diaphragm. On the right, some nodes lie within the fibrous pericardium anterior to the intra-thoracic end of the inferior vena cava. Their afferents drain the central diaphragm, while those on the right also drain the convex surface of the liver. Their efferents pass to the posterior mediastinal, parasternal and brachiocephalic nodes.
- Posterior group: the posterior group consists of a few nodes that lie on the posterior aspect of the crura and connects with the lateral aortic and posterior mediastinal nodes.
The visceral lymph nodes are responsible for the lymphatic drainage of the thoracic viscera such as the heart and the lungs. These nodes include the brachiocephalic nodes, the posterior mediastinal nodes and the tracheobronchial nodes.
For more details about the lymphatics of the thoracic cavity and viscera, take a look below:
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Abdominal lymph nodes
The lymphatic nodes that drain the abdominal wall are also arranged into superficial and deep groups.
Superficial lymphatic vessels accompany the subcutaneous blood vessels. Vessels from the lumbar and gluteal regions run with the superficial circumflex iliac vessels. Those from the infra-umbilical skin run with the superficial epigastric vessels. Both drain into the superficial inguinal lymph nodes. The supra-umbilical region is drained by vessels running obliquely up to the pectoral and subscapular axillary nodes, and there is some drainage to the parasternal nodes.
The deep lymphatic vessels of the abdomen accompany the deep arteries. The vessels from the posterior portion of the abdominal wall pass with the lumbar arteries to drain into the lateral aortic and retro-aortic nodes. Vessels from the upper anterior abdominal wall run with the superior epigastric vessels to the parasternal nodes. Vessels of the lower abdominal wall drain into the circumflex iliac, inferior epigastric and external iliac nodes.
The lymphatic drainage of the abdominal viscera occurs almost exclusively through the thoracic duct. Some lymphatic drainage may occur across the diaphragm from the bare area of the liver and the uppermost retro-peritoneal tissues, but this is probably of little clinical consequence other than during obstruction of the thoracic duct.
The lymph nodes of the retroperitoneal tissues lie around the abdominal aorta and form pre-aortic, lateral aortic the retro-aortic groups. Collectively, they are referred to as the para-aortic lymph nodes, and clinically it is difficult to distinguish between them, either at surgery or on cross-sectional imaging.
Pre-aortic group of lymph nodes
The pre-aortic nodes tend to lie around the origins of the anterior (visceral) arteries and receive lymph from the gastrointestinal tract and its accessory structures (liver, spleen, pancreas) from the abdominal oesophagus to the level of the anus. They give rise to lymphatic vessels, which drain upwards to form the intestinal trunks that enter the abdominal confluence of lymph trunks. They are divisible into coeliac, superior mesenteric and inferior mesenteric groups, being near the origins of these arteries.
Celiac lymph nodes
The coeliac nodes lie anterior to the abdominal aorta around the origin of the coeliac artery. They are a terminal group and receive lymph draining from the regional lymph nodes around the branches of the coeliac artery (gastric, hepatic and pancreaticosplenic nodes) and from the lower pre-aortic groups (the superior mesenteric and inferior mesenteric). The coeliac nodes give rise to the right and left intestinal lymph trunks.
- Gastric lymph nodes: There are numerous gastric lymph node groups. They drain the stomach, upper duodenum, abdominal oesophagus and the greater omentum into the coeliac group.
- Hepatic lymph nodes: The hepatic nodes extend in the lesser omentum along the hepatic arteries and bile duct. They vary in number and site, but almost always occur at the junction of the cystic and common hepatic ducts (the cystic node), alongside the upper (common) bile duct and in the anterior border of the epiploic foramen. Hepatic nodes drain the majority of the liver, gallbladder and bile ducts, but also receive drainage from some parts of the stomach, duodenum and pancreas. They drain into the coeliac nodes and thence to the intestinal trunks.
- Pancreaticosplenic lymph nodes: The pancreaticosplenic nodes drain the spleen, pancreas and parts of the stomach into the coeliac nodes.
Superior mesenteric and inferior mesenteric lymph nodes
These nodes lie anterior to the abdominal aorta near the origin of their respective arteries. The superior and inferior mesenteric nodes are preterminal groups of the alimentary canal from the duodenojejunal flexure to the upper anal canal. They collect lymph from the outlying groups, including the mesenteric, ileocolic, colonic and pararectal nodes and drain into the coeliac nodes.
Lateral aortic group of lymph nodes
The lateral aortic nodes lie on either side of the abdominal aorta anterior to the medial margins of psoas major, diaphragmatic crura and sympathetic trunks. On the right, some nodes lie lateral and anterior to the inferior vena cava near the end of the right renal vein. Nodes rarely lie between the aorta and inferior vena cava where they are closely related.
The lateral aortic nodes drain the viscera and other structures supplied by the lateral and dorsal aortic branches. The upper lateral groups receive the lymph drainage directly from the suprarenal glands, kidneys, ureters, gonads, uterine tubes and upper uterus. They also receive lymph directly from the deeper tissues of the posterior abdominal wall. The lateral aortic group drains into the two lumbar lymph trunks, one on each side, which terminate in the confluence of lymph trunks. A few vessels may pass to the pre-aotic and retro-aortic nodes, while others cross the midline to flow into the contralateral nodes, forming a loose plexus.
Retroaortic group of lymph nodes
This is the smallest of all the para-aortic lymph nodes and has no particular areas of drainage, although it may receive some lymph directly from the paraspinal posterior abdominal wall. Retro-aortic nodes are effectively peripheral nodes of the lateral aortic groups and provide interconnections between surrounding groups.
Mesenteric lymphadenitis is an inflammation of the mesenteric lymph nodes. This condition is a cause of acute and chronic pain and presents mainly in children and teenagers. Because the nodes are usually in the right lower quadrant of the abdomen, mesenteric lymphadenitis can mimic appendicitis. This condition is self-limited and its treatment involves supportive care which includes pain management and adequate hydration.
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