Review of the
Lymphatic System
G. Skladzien, M.D.
Clinical Anatomy
Summer 2007
Review of the Lymphatic System:
lecture objectives
Describe the structure and function of the
lymphatic system.
Identify the major lymphatic organs of the body.
Describe a lymphatic capillary and duct.
Describe the structure and function of a lymph
node.
Describe the drainage patterns of the right
lymphatic duct and the thoracic duct.
Relate the anatomy of the lymphatic system to
common clinical situations.
Lymphatic System: functions
1.
Return lymphatic fluid to venous limb of
circulatory system
2.
Remove foreign chemicals and organisms
from lymph and blood (lymph nodes and
spleen) and process and participate in the
humoral and cellular control of antigens
3.
Generate and disseminate WBCs and
antibodies from lymph nodes and lymphatic
organs to target sites in the body
Lymphatic system
structures
Review of the Lymphatic System
Lymph [Latin,
l
ympha
, clear spring water]
Composed of a filtrate of plasma, containing
water, electrolytes, smaller protein molecules
(albumin, clotting factors), PMNs, lymphocytes,
monocytes
Similar to interstitial fluid
Lymph from small bowel includes chylomicrons
Flow/24
o
equals plasma volume, all returned to
venous system via Rt + Lt thoracic ducts
Review of the Lymphatic System
Lymph passes from interstitium into lymphatic
capillaries – thin-walled, valved channels
Lymph capillaries are blind-end tubes that lead
away from the tissue.
Lymph travels through the lymph capillaries to
small lymph vessels. Like veins, the walls of
lymph vessels have smooth muscle that
contracts and propels lymph away from the
tissues. Lymph vessels contain valves that
prevent lymph from flowing backward.
No lymphatic drainage of CNS
Capillary cell membrane
Formation of lymphatic fluid
Lymph capillary
Nucleus
Lumen
Basement
Membrane
Lymph capillary function
Lymph capillaries possess valves which allow for
uni-directional flow of lymphatic fluid
Thoracic duct
histologic section
All lymphatic
flow returns
to central
veins
Lymphangiitis
Infection of lymphatic channels
Lymphedema
Painless
nonpitting
edema of extremities
1
o
due to
absence or malfunction of
lymphatic vessel valves
2
o
due to acquired lymphatic obstruction,
surgical removal of lymph nodes and
vessels
Lymphedema
Lymphedema
Secondary Lymphedema
Surgery and radiation from breast CA
melanoma
Tumors such as prostate, lymphoma
Damage or obstruction of previously
normal lymphatic channels
From recurrent lymphangiitis
From filariasis (nematodes transmitted by
mosquitoes or arthropods)
Lymph nodes
Lymph is channeled through multiple lymph
nodes where the fluid is filtered of particulate
matter (carbon in pulmonary lymphatics),
viruses, bacteria, fungi, and parasites, foreign
proteins and other chemicals can by
phagocytized by macrophages
Malignant cells that embolize off of tumors can
metastasize to nodes
Lymph nodes
Lymph nodes become enlarged in situations when the
node is either stimulated by local infection or becomes
infected
General term for enlarged lymph nodes is
“lymphadenopathy”
Lymph nodes may become enlarged due to primary
lymphoid neoplasia - lymphoma
Clinically palpable nodes also present with tumor
metastasis or inflammatory/autoimmune disease
Many lymph nodes locations are not accessible to
physical exam though can be detected on radiographic/
ultrasound/MR studies
Lymphatics of the face and scalp converge on the deep lymphatics
Deep cervical
lymph nodes
follow the
jugular veins
and trachea
Cervical lymphadenopathy
Lymphatic drainage of the breast is predominately via axillary lymphatics
Internal thoracic nodes drain medial quadrants
Inguinal lymphadenopathy
Cysterna chyli is
the reservoir that
drains lymph from
the abdominal
viscera and lower
body into the
thoracic duct
Spleen, thymus and enteric
lymphoid tissue
Spleen is a large lymphatic organ situated in dorsal
mesentery of stomach which functions to filter and
breakdown defective and old platelets, PMNs and RBCs
Filters blood,
not lymph
Composed of red pulp and white pulp
Spleen also contains many germinal centers responsible
for antibody production to blood-born organisms and
antigens
In pathologic conditions extramedullary myelopoesis can
occur in spleen
Splenectomy increases a patient’s risk for sepsis mostly
2
o
to encapsulated Gram +ve cocci termed “overwhelming
post-splenectomy sepsis”
Thymus, Spleen, and enteric
lymphoid tissue
Thymus [Greek,
thymos
, sweetbread, mind]
Thymus is a substantial lymphatic organ in the
anterior mediastinum formed from thee ventral
portions of the 3
rd
and 4
th
branchial pouches
Site of maturation and possible site of origin
of “T cells”
Atrophies with age + replaced by adipose
Can be site of neoplasia - thymoma
Normal thymus in child AP CXR
Thymus
CXR pa + lateral
Normal thymus
Thymoma
Enteric lymphoid tissue
Multiple lymphoid follicles present in submucosa
of pharynx, intestine (Peyer’s patches of terminal
ileum) and appendix
Termed - Mucosa Associated Lymphoid Tissue -
MALT
These structures are
NOT
lymph nodes
Important in production of IgA in mucous
secretions
Can be foci of neoplasia
Hypertrophy of appendiceal lymphatic tissue is
one cause of acute appendicitis
Sub-mucosal lymphoid nodule
small intestine
Palatine tonsil
Lymphatic tissue of tongue and pharynx
Histology of
lymphoma
Normal
lymph
node
Lymphoma is a primary neoplasm of any lymphatic tissue –
-
lymphocytes or histiocytes (monocytes and macrophages)
lymph
node, MALT, or any organ containing lymphoid tissue i.e. thyroid
Anterior mediastinal lymphoma
CSF
Produced ?
Choroid plexus
Reabsorbed into dural veins ?
Arachnoid granulations
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