Lymphatic Drainage of the thorax

Question 1

What is the importance of the lymphatic system

Answer 1

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

Question 2

What is the lymphatic system

Answer 2

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

Question 3

What are the lymph nodes

Answer 3

Enlargements along the lymph vessels- enlarged and visible in infection

Question 4

What is the difference in the roles of the lymph vessels and the lymph nodes

Answer 4

Vessels- carry fluid

Nodes- filter fluid

Question 5

Describe the basic anatomy of the lymphatic system

Answer 5

§ 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

Question 6

Describe the lymph vessels

Answer 6

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).

Question 7

What may be present in the lymph fluid

Answer 7

Cell debris
Dead cells
Pathogens
cell products (hormones)

Question 8

Describe the anatomy of a lymph node

Answer 8

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.

Question 9

What is the purpose of the lymph nodes

Answer 9

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.

Question 10

Why are cancers likely to migrate through the lymph nodes

Answer 10

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.

Question 11

What happens to lymph nodes that contain pathogens

Answer 11

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.

Question 12

Describe the enlargement of the lymph nodes

Answer 12

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

Question 13

Describe the locations of the lymph nodes

Answer 13

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.

Question 14

Describe the appearance of the lymph

Answer 14

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

Question 15

Describe the movement of the lymph

Answer 15

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

Question 16

What are the key facts to remember about the lymphatic system

Answer 16

§ 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

Question 17

Describe lymphatics of the thoracic wall

Answer 17

Lymph drains into nodes associated with:
internal thoracic arteries (parasternal)
ribs (intercostal)- heads and neck
diaphragm (diaphragmatic)

Question 18

Describe the lymphatic drainage of the thoracic wall

Answer 18

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

Question 19

Describe the passage of the thoracic duct

Answer 19

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

Question 20

Describe the lymphatic drainage of the lungs

Answer 20

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.

Question 21

What forms the bronchomediastinal trunk

Answer 21

§ Left and right Broncho-mediastinal trunks formed by:
o Tracheo-bronchial lymph vessels.
o Parasternal vessels.
o Brachio-cephalic nodes.

Question 22

Describe the lymphatics of the lung

Answer 22

§ Largest collection of lymph nodes at the tracheo-bronchial junction.
§ Lymph nodes found WITHIN the lungs and

Question 23

Describe the lymphatics of the heart

Answer 23

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.

Question 24

Describe the lymphatics of the posterior mediastinum

Answer 24

§ Nodes on the aorta receive lymph from the oesophagus, diaphragm, liver and pericardium.
§ Lymph then drains into the thoracic duct and posterior mediastinum.