Lymphatic vessels – Vasa lymphoidea
2
10
Lymphatic capillaries are blind-ended tubes with a special microscopic structure that ensures a unidirectional flow of extracellular fluid. Lymphatic capillaries drain into the bigger lymphatic vessels. Lymph nodes are found along the network of lymphatic vessels. Lymphatic vessels contain valves, which supports the unidirectional fluid to the lymphatic trunks and ducts. The lymphatic ducts drain lymph into the venous blood at the venous angle. 1 Lymphatic capillaries (vasa lymphocapillaria) – collect extracellular fluid with metabolic substances, antigens (viruses, bacteria and/or pre-tumor or tumor cells) and antigen-presenting cells – form a lymphocapillary network (rete lymphocapillare), whose wall is made of only one layer of endothelium (running together with blood capillaries and venules; in the small intestine, run in the axis of a villus) 2 Lymphatic vessels (vasa lymphoidea) – are thin-walled vessels containing valves – their course is interrupted by lymph nodes – in organs, there are subcapsular and deep lymphatic networks – in extremities, there are superficial and deep collectors accompanying particular veins – the superficial collectors are located in subcutaneous tissue and empty into the cubital and axillary nodes in the upper limb, and the popliteal and inguinal nodes in the lower limb – the deep collectors run together with the deep vessels 2.1 Collectors of the upper extremity 2.1.1 Lateral collectors – to the axillary lymph nodes along the cephalic vein 2.1.2 Medial collectors – to the axillary lymph nodes along the basilic vein (drain the superficial cubital lymph nodes of the cubital region) 2.1.3 Anterior collectors – to the superficial cubital lymph nodes along the median antebrachial vein 2.2 Collectors of the lower extremity 2.2.1 Medial collectors (10–15) – to the superficial inguinal lymph nodes, along the great saphenous vein 2.2.2 Lateral collectors (1–3) – to the superficial inguinal lymph nodes, along the tributaries of the great saphenous vein 2.2.3 Posterior collectors (2–3) – to the superficial popliteal lymph nodes, along the small saphenous vein 2.3 Deep lymphatic vessels – accompany the deep vessels of the lower extremity, – to the deep popliteal lymph nodes and the deep inguinal lymph nodes 3 Lymphatic trunks (trunci lymphatici) Paired 3.1 Jugular trunk (truncus jugularis) – lymphatic drainage from half of the head and neck 3.2 Subclavian trunk (truncus subclavius) – lymphatic drainage from the collectors of the upper extremity – the axillary lymphatic plexus is a network of lymphatic vessels 3.1 and lymph nodes in the axilla, which drains in the subclavian trunk 3.3 Bronchomediastinal trunk (truncus bronchomediastinalis) 4.1 – lymphatic drainage from half of the thorax 3.2 3.4 Lumbar trunk (truncus lumbalis) – lymphatic drainage from the lower extremity and half of the pelvis 3.3 Unpaired 3.5 Intestinal trunk (truncus intestinalis) – lymphatic drainage from the unpaired abdominal organs 4 Lymphatic ducts (ductus lymphatici) – irregular drainage areas 4.2 4.1 Right lymphatic duct (ductus lymphaticus dexter) – a short duct originating from the 3 main lymphatic trunks: the right jugular, right subclavian and right bronchomediastinal trunks 4.2.1 – collects lymph from the right half of the head and neck, right upper extremity and right half of the thoracic cavity 3.5 – there is an exception: lymphatic drainage from the right half of the heart goes to the thoracic duct 3.4 4.2 Thoracic duct (ductus thoracicus) – originates from the lumbar trunks – collects lymph from both lower extremities, pelvis, abdominal cavity, the left half of the thoracic cavity, left upper extremity and the left half of the head and neck – is divided into 4 parts according to its course: lumbar, abdominal, thoracic and cervical parts 4.2.1 Cisterna chyli – a widened situated at the beginning of the thoracic duct at the level of T11–L1 – there is an exception: lymphatic drainage from the 4th to 10th segment of the left lung and left half of the heart runs to the right lymphatic duct
• • • • • •
•
•
319