The Lymphatic System

Question 1

What are the functions of the lymphatic system?

Answer 1

• drains excess interstitial fluid
• transports dietary lipids from GI tract to blood
• protects against invasion through immune responses
• unwanted role in providing at least one pathway for spread of malignancy

Question 2

What are the features of lymphatic capillaries?

Answer 2

flap like mini valve
most ECF is reabsorbed by the capillaries
pressure leaks out of them due to Starling’s Law

Question 3

What aids lymph flow?

Answer 3

• Low pressure conduits
• Milking action of active skeletal muscle, numerous valves and pressure changes in the thorax (Deep lymphatics bundled in sheaths of CT with arteries – pulsations promote flow)
• Smooth muscle in walls of trunks and ducts contract rhythmically
  Physical activity

Question 4

What are the roles of lymph nodes?

Answer 4

• secondary lymph organs
• normally in groups
• filter lymph as macrophages remove and destroy microorganisms and debris
• activate the immune system as lymphocytes strategically located to monitor antigen presence

Question 5

What does the right lymphatic duct do?

Answer 5

• drains right upper quadrant (right side of head, neck, thorax and right arm)
• duct drains into the junction between the internal jugular vein and subclavian veins (venous angle)

Question 6

What does the thoracic duct do?

Answer 6

• drains rest of body
• begins in abdomen in cisterna chyle
• duct ends at left venous angle

Question 7

What superficial drainage is there?

Answer 7

• cervical nodes drain above the clavicle
• axillary nodes between the clavicle and umbilicus
• inguinal nodes below umbilicus to drain to deep inguinal nodes

Question 8

What lymphatic drainage is there in the head and neck?

Answer 8

efferent vessels enter superficial cervical lymph nodes along the course of the EJV over the SCM, into the deep chain
deep cervical nodes are vertical along the IJV with efferent vessels from the right jugular trunk

Question 9

What are the main lymph nodes in the head and neck?

Answer 9

Preauricular, postauricular, parotid, submental, submandibular, supraclavicular, posterior cervical, anterior cervical, deep cervical, superficial cervical, occipital

Question 10

What are the 2 groups of inguinal lymph nodes?

Answer 10

• horizontal (run superficial to the inguinal ligament, drain anterior abdominal wall, perineum and external genitalia excluding testes)
• Vertical (lie along termination of great saphenous vein, drain most of superficial lymphatics from leg)

Question 11

Where do the efferents from inguinal superficial lymph nodes drain?

Answer 11

To the deep inguinal nodes: 3 nodes in the femoral canal, also receive lymphatics from deep structures of leg

Question 12

What structures allow deep drainage of the thorax?

Answer 12

bronchomediatsinal trunks, bronchopulmonary nodes, interlobar lymph vessels, sub-pleural plexus, inferior trachea bronchial nodes, interpulmonary nodes, superior tracheobronchial nodes, tracheal nodes

Question 13

What do Kerley B lines suggest?

Answer 13

Pulmonary oedema

Question 14

What are the lymphatics of the posterior abdominal wall?

Answer 14

Lie along the aorta, IVC and iliac vessels

• external and internal iliac surrounded by lumbar lymph nodes and R. and L. lumbar trunks
• abdomen vessels surrounded by pre-aortic lymph nodes and intestinal lymph trunk
• intestinal and R. + L. lumbar trunks drain to cisterna chyle

Question 15

How does the lymphatic system vary between infants and older adults?

Answer 15

Infants - lymphoid tissue increases to twice adult mass between 6-9 years then regresses through puberty, tonsils larger during childhood, immune response to infection is immature in first few months of life
Adults - number and size of lymph nodes decreases with age, some lymphoid elements lost, nodes more fibrotic and fatty than in young so impaired ability to resist infection

Question 16

Which nodes are accessible for examination in the head and neck?

Answer 16

preauricular
postauricular
occipital
tonsillar
submandibular
submental
superficial anterior cervical
deep cervical
posterior cervical
supraclavicular
infraclavicular

Question 17

Which nodes are accessible for examination in the arms?

Answer 17

axillary
anterior axillary (pectoral)
lateral (brachial)
mid axillary (central)
posterior (subscapular)
Epitrochlear

Question 18

Which nodes are accessible for examination in the legs?

Answer 18

superficial superior inguinal
superficial inferior inguinal
popliteal (occasionally)

Question 19

What is the role of the spleen?

Answer 19

• site for lymphocyte proliferation, immune surveillance and response
• blood cleansing functions (extracts aged and defective blood cells and platelets, macrophages remove debris and foreign matter)
• stores/release breakdown products of RBC
• erythrocyte production In fetus
• stores platelets

Question 20

What is the role of the thymus?

Answer 20

• secretes thymopoietin and thymosins causing T lymphocytes to become immunocompetent
• prominent in newborns continues to grow 1st year when highly active
• after puberty atrophy starts

Question 21

What is the role of tonsils?

Answer 21

Different locations - palatine, lingual, pharyngeal, tubal

- gather and remove pathogens entering the pharynx in food or inhaled air

Question 22

What are Peyer’s patches?

Answer 22

• large isolated clusters of lymphoid tissue located in the wall of distal small intestine
• lymphoid follicles concentrated in appendix wall which destroy bacteria and prevent pathogens breaching intestinal wall and generate memory lymphocytes for LT immunity

Question 23

What is Starling’s Law?

Answer 23

Explains how fluid flows out of capillaries due to high hydrostatic pressure in capillaries ]#and then flow back into capillaries due to oncotic pressure (proteins)

Question 24

How does lymph flow?

Answer 24

Lymphatic plexus -> lymphatic collecting vessels -> lymph nodes -> lymph vessels -> lymph duct -> venous circulation

Question 25

What is the lymphatic plexus?

Answer 25

Collection of capillary and lymphatic vessels

Question 26

What is lympathic filariasis?

Answer 26

Also called elephantitis
Parasitic worms get transported via mosquitoes that live in the lymph system.
It halts lymph absorption causing oedema
can cause scrotal hydrocele

Question 27

What is the role of lymphatic trunks?

Answer 27

Drain lymphatic vessels and enter the R. and L. subclavian vein
Most trunks in pairs except for intestinal trunk is singular

Question 28

What are the superior trunks?

Answer 28

L and R jugular
L and R subclavian
L and R bronchomediastinal (R forms right lymphatic duct and L forms thoracic duct)

Question 29

What are the inferior trunks?

Answer 29

R and L lumbar trunks which are along the external and internal iliac
Intestinal trunk which form cisterna chyli -> thoracic duct

Question 30

What is the role of the right lymphatic duct?

Answer 30

Drains upper right quadrants (ride side of head,

Question 31

Where are cervical nodes?

Answer 31

Lie along the course of the EJV/over the SCM to then drain into the deep chain

Question 32

What structures drain into the deep system?

Answer 32

thorax, abdomen, pelvis and perineum, head and neck nodes lie along IJV

Question 33

What are the axillary lymph nodes?

Answer 33

Humeral, pectoral, subscapular lymph nodes drain into central nodes -> apical nodes -> supraclavicular nodes -> subclavian lymphatic trunk

Question 34

What are the sentinel lymph nodes?

Answer 34

First node group that drain a tumour, removed to observe if the tumour has spread

Question 35

What is Virchow’s node?

Answer 35

supraclavicular lymph node

if hardened - strong sign of cancer in the abdomen (often gastric cancer that has spread)

Question 36

What are the main lymphoid organs?

Answer 36

Spleen
Thymus
Tonsils/adenoids
Peyer's patches
Myeloid tissue in bone marrow