Lymphatic Drainage of the thorax Flashcards
What is the importance of the lymphatic system
More fluid leaves blood capillaries than returns to them
Uncompensated fluid movement from blood to the extracellular fluid would result in oedema and loss of blood volume
Lymphatic vessels drain excess extracellular fluid back into the blood
Ensure foreign particles come into contact with immune system
What is the lymphatic system
Network of tissues and organs consisting of lymph vessels, lymph nodes and lymph
Includes tonsils, adenoids, spleen and thymus
600-700 lymph nodes in humans
Filter the lymph before it returns to the circulatory system
Also present in the brain
What are the lymph nodes
Enlargements along the lymph vessels- enlarged and visible in infection
What is the difference in the roles of the lymph vessels and the lymph nodes
Vessels- carry fluid
Nodes- filter fluid
Describe the basic anatomy of the lymphatic system
§ Upper right quadrant of the body drains into the right subclavian vein.
o Head, neck, upper right limbs and some thorax.
§ Rest of body drains into the thoracic duct and then the left subclavian vein.
o Rest of body
Upper right quadrant= right jugular trunk, right subclavian trunk, right bronchomediastinal trunk- same on left
Describe the lymph vessels
Begin as ‘porous’ blind-ended lymphatic capillaries in the tissues and converge to form larger vessels.
Present in most areas of the body except the brain, bone marrow and avascular tissues such as the epithelia and cartilage
Important in fat transport- chylomicrons releases into IF and enter lymphatic capillaries (known as lacteals in the small intestine).
What may be present in the lymph fluid
Cell debris
Dead cells
Pathogens
cell products (hormones)
Describe the anatomy of a lymph node
Small (<2.5cm long) Found along lymph vessels Contain lymphocytes and macrophages Can act upon foreign bodies in the lymph Drainage from infected regions detectable in enlarged lymph nodes Armpit, groin, neck nodes are palpable.
What is the purpose of the lymph nodes
Small encapsulated structures that interrupt the course of lymphatic vessels and contain elements of the body’s defence system, such as clusters of lymphocytes and macrophages.
They act as elaborate filters that trap and phagocytose particulate matter in the lymph that percolates through them. In addition, they fight and protect against foreign antigens found in the lymph.
Why are cancers likely to migrate through the lymph nodes
Because lymph nodes are efficient filters and flow through them is slow, cells that metastasize from primary tumors and enter lymphatic vessels often lodge and grow as secondary tumors in lymph node.
What happens to lymph nodes that contain pathogens
Lymph nodes that drain regions that are infected or contain other forms of disease can enlarge or undergo certain physical changes, such as becoming ‘hard’ or ‘tender’. These changes can be used by clinicians to detect pathologic changes or to track the spread of disease.
Describe the enlargement of the lymph nodes
Common - Infection
Commonly enlarged in the neck in children due to the large number of respiratory infections
Less common - Cancers
TB, HIV, Arthritis, reactions to drugs
Describe the locations of the lymph nodes
Cervical (along course of IJV) Axillary Deep nodes (aorta, celiac trunk and superior and inferior mesenteric arteries) Pericranial ring (base of head) Tracheal nodes (trachea and bronchi) Inguinal nodes (inguial ligament) Femoral nodes (femoral vein)
Many drain the body’s surface, digestive system and respiratory system.
Describe the appearance of the lymph
Clear and odourless in most vessels
Opaque and milky from small intestine due to the fats absorbed
Called chyle – (Greek – “juice”)
Contains white blood cells, pathogens, hormones, cell debris, fats
Describe the movement of the lymph
Slow and sporadic – no “pump”
Maintained by action of adjacent structures
Skeletal muscles and the pulses in arteries
Unidirectional due to the presence of valves
What are the key facts to remember about the lymphatic system
§ Lymph vessels have valves to prevent backflow and are ‘blind-ended’.
§ Lymphatic vessels get larger as you get closer to the point of re-entry to the circulation.
§ Bifurcation of trachea is the largest concentration of lymph node
Describe lymphatics of the thoracic wall
Lymph drains into nodes associated with:
internal thoracic arteries (parasternal)
ribs (intercostal)- heads and neck
diaphragm (diaphragmatic)
Describe the lymphatic drainage of the thoracic wall
Parasternal nodes drain into bronchomediastinal trunks
Intercostal nodes in the upper thorax also drain into the bronchomediastinal trunks, whereas those in the lower thorax drain into the thoracic duct.
Superficial regions of the thoracic wall drain mainly into axillary lymph nodes or parasternal nodes
Diaphragmatic- brachiocephalic nodes or aortic/lumbar nodes
Describe the passage of the thoracic duct
Main channel draining most of the body
Begins at the cisterna chyli
drains abdomen, pelvis, perineum and lower limbs
Begins at L2 vertebral level
Enters behind oesophagus through diaphragm
Ascends on right of midline
Between aorta and azygous vein
Crosses over onto left at T5
Empties into junction of left internal jugular and left subclavian vein
Describe the lymphatic drainage of the lungs
Superficial, or subpleural, and deep lymphatic of the lungs drain into the tracheobronchial nodes around the roots of the lobar and main bronchi and along the sides of the trachea. As a group, these lymph nodes extend from within the lung, through the hilum and root, and into the posterior mediastinum.
Unite with vessels from parasternal and brachiocephalic nodes anterior to brachiocephalic veins to form bronchomediastinal trunks.
What forms the bronchomediastinal trunk
§ Left and right Broncho-mediastinal trunks formed by:
o Tracheo-bronchial lymph vessels.
o Parasternal vessels.
o Brachio-cephalic nodes.
Describe the lymphatics of the lung
§ Largest collection of lymph nodes at the tracheo-bronchial junction.
§ Lymph nodes found WITHIN the lungs and
Describe the lymphatics of the heart
The lymphatics of the heart follow the coronary arteries and drain mainly into:
brachiocephalic nodes- anterior to the brachiocephalic veins
tracheobronchial nodes- at the inferior of the end of the trachea.
Describe the lymphatics of the posterior mediastinum
§ Nodes on the aorta receive lymph from the oesophagus, diaphragm, liver and pericardium.
§ Lymph then drains into the thoracic duct and posterior mediastinum.
