Lymph nodes are oval, bean-shaped structures scattered throughout the body along lymph vessels that usually measure 1-25 mm in length. They are concentrated along respiratory and gastrointestinal tracts, in mammary glands, axillae, and groin. Lymph nodes filter lymph fluid to trap pathogens, debris, and tumor cells. They have an outer capsule and inner parenchyma differentiated into a cortex and medulla. Lymph enters through afferent vessels and stagnates in sinuses, allowing immune cells time to respond before exiting through efferent vessels.

1. LYMPH NODE

2. generally...
–oval, bean shaped structures scattered throughout body along lymph
vessels
–Usually 1-25 mm in length
–may be deep or superficial
–concentrated along the respiratory tree and GI tract, in the mammary
glands, axillae, and groin
–filter lymph fluid to trap foreign organisms, cell debris, and tumor cells

3. Anatomical picture

4. Usually 1-25
mm in length,
but they can
be larger.
Greatest
concentration
near groin,
axilla, neck,
thorax, and
along gut
tube in
abdomen.

5. Structure of a Lymph Node
➢Outermost is the covering called capsule
composed of fibrous connective tissue
➢Capsule contains the
parenchyma or stroma
➢Stroma is
differentiated into
cortex & medulla
•Trabeculae extend
from cortex to medulla

6. ● outer cortex
● - filled with lymph follicles
-outer edge of follicle contains more T cells
- inner germinal
center is the site of B-
cell proliferation
●inner medulla
-medullary cords of
lymphocytes, Cortex
macrophages, plasma
cells.
Medulla

8. Cytology of the lymph node
The normal or reactive lymph node is
composed of
➢ Transient B and T lymphocytes
➢ Antigen processing and presenting
cells
➢ Replicating B and T lymphocytes (in
response to antigen)
➢ Persistent and transient final
effector cells
➢ Macrophages

9. B lymphocytes are
located primarily in the follicles and
perifollicular areas
T lymphocytes are
found primarily in the interfollicular or
paracortical areas of the lymph node.

10. physiology

11. •Macrophages and lymphocytes reside in the
outer ("cortex") region of a node.
Afferent (entering) vessels bring lymph in.
●
●Lymph first enters into a large subcapsular
sinus & then into many small sinuses.
●Throughout the node are lymph sinuses
crisscrossed by reticular fibers

12. •Macrophages reside on these fibers where
they phagocytise foreign matter.
•The node acts as
a “settling tank,”
because there are
fewer efferent
vessels, lymph
stagnates
somewhat in the
node.

13. ●This allows lymphocytes and macrophages time
to carry out their protective functions
●Reticular fibres filter and trap damaged
cells, microorganisms, foreign substances, tumor
cells.
●Macrophages phagocytize some, lymphocytes
destroy some by immune defenses.
"Medulla" is the inner collecting area.
Efferent (exiting) vessel leaves at the "hilus.

14. Distribution

15. Lymph nodes of clinical importance have been
put under 5 main groups:
➢ Cervical groups
➢ Axillary groups
➢ Inguinal groups
➢ Epitrochlear lymph nodes
➢ Popliteal lymph nodes

17. Cervical groups
● Right & left groups
● each divided into: horizontal (circular)
and vertical
The horizontal group include:
> sub-mental
> sub-mandibular
> parotid
> pre-auricular
> post-auricular
> occipital

18. The vertical group include:
> superficial (along external jugular vein)
> deep (along internal
jugular vein)
> Prelaryngeal
> Pretracheal
> Paratracheal

19. Axillary groups
● Right & left groups
● each divided into 5 groups:
> Anterior (pectoral)
> posterior (sub-scapular)
> medial (along chest wall)
> lateral (humeral)
> central

21. Inguinal groups
Horizontal group lies along the
inguinal ligament (both above and over)
Vertical group is beside the
great saphenous vein in the proximal thigh.
Iliac nodes:aboveand deep to inguinal
ligament

23. Epitrochlear nodes
3 cm proximal to the medial
humeral epicondyle, in the groove between the
biceps and triceps brachii.

24. Thank you.....