It’s important to know the major lymph node groups and the areas they drain. This information helps you localize infections and understand how cancers spread.
A sentinel node is the first lymph node (within a regional group) that receives lymph from a specific area. Because it’s the first “stop,” it’s often the first node involved in cancer spread. A sentinel lymph node biopsy helps detect early metastasis. It’s performed by injecting a blue dye or radioactive tracer into the drainage area; the first node to take up the dye/tracer is identified as the sentinel node.
There are 2 major groups: superficial and deep.
Superficial nodes
These form a T-shaped arrangement, located just below the inguinal ligament and along the great saphenous vein. They drain superficial structures (i.e., structures above the deep fascia). Drainage areas include:
Deep nodes
These are located medial to the femoral vein within the femoral sheath. Cloquet’s node is the most superior node in this group, just under the inguinal ligament. Deep inguinal nodes drain the deep lymphatics of the distal lower extremity and perineum, including the glans penis and clitoris. They drain into the external iliac lymph nodes and finally into paraaortic nodes.
Lymphatic drainage depends on the specific structure.
Following is a list of them:
| Part of GIT | Draining lymph nodes |
|---|---|
| Esophagus | Mediastinal lymph nodes |
| Stomach, pancreas, liver, spleen, upper duodenum | Celiac lymph nodes |
| Lower part of duodenum (distal to major duodenal papilla), jejunum, ileum, colon up to the proximal ⅔ of transverse colon | Superior mesenteric nodes |
| Distal ⅓ of transverse colon to upper rectum | Inferior mesenteric lymph nodes |
| Lower part of rectum, anal canal above pectinate line | Internal iliac nodes* |
| Anal canal below pectinate line | Superficial inguinal nodes |
*The bladder drains to internal iliac nodes (finally into para aortic) while kidneys, adrenals and upper part of renal collecting system drain directly into para aortic nodes.
Breast lymph drains primarily to two node groups:
The thoracic duct begins at the level of the second lumbar vertebrae as the dilated cisterna chyli. It enters the thoracic cavity through the aortic opening of the diaphragm. It then passes through the posterior and superior mediastinum and finally drains into the junction of the left subclavian vein and the internal jugular vein at the base of the neck.
The abdominal and thoracic parts of the thoracic duct show active peristalsis. It carries lymph (chyle) from all areas of the body except those drained by the right lymphatic duct (see below).
Cervical course of the thoracic duct. The thoracic duct enters the neck lateral to the esophagus, ascending superiorly and laterally behind to the carotid and internal jugular vein before turning inferiorly and anteriorly to join the venous circulation at the confluence of the internal jugular vein and subclavian vein.
The right lymphatic duct drains lymph from the right side of the head and neck, right upper extremity, right side of the thorax, right lung, right side of the heart, and a part of the liver. It opens into the right subclavian vein.
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