Lymphatic vessels and nodes
Depending on their depth, lymphatic vessels (vasa lymphatica) are divided into two main groups:
- Superficial (vasa lymphatica superficialia) — run in the subcutaneous adipose tissue layer.
- Deep (vasa lymphatica profundae) — follow parallel to major blood (primarily arterial) vessels.
Vessels frequently interconnect, forming lymphatic plexuses (plexus lymphatici). Additionally, anastomoses exist between the superficial and deep networks.
Lymph nodes (nodi lymphoidei / lymphatici) are located along the path of the vessels. They function as biological filters: lymph arrives via afferent vessels (vasa afferentia), passes through the node sinuses (where it is cleansed of bacteria and tumor cells and enriched with lymphocytes), and then leaves via efferent vessels (vasa efferentia) emerging from the hilum (hilum). Groups of nodes draining a specific region are called regional nodes.
Internal structure of a lymph node
Externally, the node is covered by a dense connective tissue capsule (capsula) containing smooth muscle cells (which allows the node to contract, propelling the lymph). Trabeculae (trabeculae (trabeculae)) extend inward from the capsule, forming the framework of the organ.
The parenchyma of the node is represented by lymphoid tissue:
- Cortex (cortex) — located peripherally.
- Medulla (medulla) — located centrally, forming the so-called medullary cords.
Spaces lined with endothelium—sinuses (subcapsular, trabecular, medullary)—are located between the parenchyma and the framework (capsule and trabeculae). Lymph flows precisely through these spaces.
Central lymphatic ducts
All lymph from the body ultimately collects into two large ducts that drain into the venous system.
1. Thoracic duct (Ductus thoracicus) The largest lymphatic collector. Collects lymph from the legs, pelvis, abdominal cavity, as well as the left halves of the thorax, neck, head, and left arm (i.e., from 3/4 of the body).
- Begins in the abdominal cavity (at the level of the second lumbar vertebra) with a dilation—the cisterna chyli (cisterna chyli).
- Formed by the confluence of the intestinal trunk and two lumbar trunks (left and right).
- Passes through the diaphragm into the thoracic cavity, ascends in the posterior mediastinum, and empties into the left venous angle.
2. Right lymphatic duct (Ductus lymphaticus dexter) A small vessel (only about 1–1.5 cm long) collecting lymph from the right arm, right halves of the thorax, neck, and head (1/4 of the body).
- Formed by the union of the right jugular, subclavian, and bronchomediastinal trunks.
- Empties into the right venous angle.
Lymph drainage from the lower limb
The lymphatic system of the legs is represented by superficial and deep pathways heading toward the inguinal region.
- Superficial lymphatic vessels are formed from the capillary networks of the foot. The medial group runs parallel to the great saphenous vein, while the lateral group runs along the small saphenous vein (some of them are interrupted in the popliteal nodes).
- All lymph from the superficial tissues collects in the superficial inguinal lymph nodes (nodi lymphoidei inguinales superficiales). They lie subcutaneously in the upper third of the thigh and are subdivided into superomedial, superolateral, and inferior groups. Lymph from the lower abdominal wall, external genitalia, and perineum also drains here.
- Deep inguinal nodes (nodi lymphoidei inguinales profundi) are located beneath the fascia lata of the thigh, adjacent to the femoral vein (including Pirogov-Rosenthal node). Lymph flows from the inguinal nodes to the external iliac nodes in the pelvic cavity.
Briefly: answers to topical questions
Which groups of lymph nodes collect lymph from the upper limb?
Lymph from the upper limb is collected by the cubital, humeral, and axillary lymph nodes.
- Cubital lymph nodes (nodi lymphoidei cubitales) receive lymph from vessels running along the radial and ulnar arteries, as well as from the dorsal aspect of the forearm.
- Humeral lymph node — located at the border of the lower and middle thirds of the arm.
- Axillary lymph nodes (nodi lymphoidei axillares) receive lymph from the superficial and deep vessels of the upper limb, including the lateral axillary nodes (nodi lymphoidei axillares laterales).
Which lymph nodes are classified as visceral nodes of the abdominal cavity?
The sources explicitly mention the following groups of lymph nodes associated with lymph drainage from the abdominal organs and the digestive system:
- hepatic lymph nodes (nodi lymphoidei hepatici);
- celiac nodes;
- gastric nodes;
- pyloric nodes (nodi lymphoidei pylorici);
- pancreaticoduodenal nodes (nodi lymphoidei pancreaticoduodenales);
- pancreatic nodes (nodi lymphoidei pancreatici);
- splenic nodes (nodi lymphoidei splenici).
Which lymph nodes are classified as parietal nodes of the pelvis?
The cited sources do not explicitly specify which pelvic lymph nodes are classified as parietal. Among the pelvic lymph nodes listed are:
- lateral common iliac nodes (nodi lymphoidei iliaci communes laterales);
- external iliac nodes (nodi lymphoidei iliaci externi);
- internal iliac node (nodus lymphoideus iliacus internus);
- sacral nodes (nodi lymphoidei sacrales).
Through which opening of the diaphragm does the thoracic duct enter the thoracic cavity?
The thoracic duct enters the thoracic cavity through the aortic hiatus of the diaphragm, alongside the aorta. The aortic hiatus is formed by the median arcuate ligament (lig. arcuatum medianum) between the crura of the lumbar part of the diaphragm.
Class and exam questions
What is the difference between afferent and efferent vessels of a lymph node?
Afferent vessels enter the node on its convex side and deliver lymph for filtration. Efferent vessels convey the filtered lymph and exit through the hilum of the node.
Which body regions are drained by the thoracic duct?
The thoracic duct collects lymph from 3/4 of the body: the lower limbs, pelvis, abdominal cavity, as well as the left half of the thorax, left arm, and left half of the neck and head.
What is the venous angle and what is its role in lymph drainage?
The venous angle is the junction where the internal jugular and subclavian veins meet. The thoracic duct empties into the left venous angle, and the right lymphatic duct empties into the right venous angle, thereby returning lymph to the vascular bloodstream.
Where are the superficial inguinal lymph nodes located?
They are located in the upper third of the thigh, just below the inguinal ligament, lying in the subcutaneous tissue superficial to the fascia lata.
What else to study on this topic
- Structure and topography of the lumbar, iliac, and sacral lymph nodes
- Formation and course of major lymphatic trunks (jugular, subclavian, bronchomediastinal)
- Topography of the thoracic duct in the thoracic cavity and its syntopy with the aorta and esophagus
- Deep and superficial lymphatic pathways of the leg and their connection with popliteal nodes
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