2. CONTENT
1. Introduction to lymphatic system
2. Lymphoid tissue and its type
3. Functions of lymphatic system
4. Lymph nodes
5. Drainage and nodes of head and neck region
6. Tonsils
7. Clinical considerations
8. conclusion
3. DEFINITION
The part of immune system that comprise of
a network of lymph vessels carrying a fluid
called lymph is the lymphatic system.
4. LYMPHATIC TISSUE
It is a specialized form of connective tissue
formed by reticular cells and reticular fibers.
The space within the meshwork is filled by
numbers of lymphocytes .
Along with lymphocytes plasma cells and
macrophages are also present.
5. FUNCTIONS OF LYMPHATIC SYSTEM
1. Defense of the body: The macrophages present
in the lymphatic tissues engulf the foreign cells
like bacteria, viruses and cancer cells.
2. Tissue drainage: The cardiovascular system
pumps about 21 liters of plasma fluid into the
tissue via capillaries ,out of which 3-4 liters of
plasma fluid fails to escape into the capillaries.
Those 3-4 liters of plasma fluid reaches to lymph
nodes via lymph vessels and finally drains into
the circulation from lymph node.
6. 3. Immunity: Lymphoid tissue is composed
of lymphocytes. B-lymphocytes, T-
lymphocytes and natural killer cells are
responsible for immunological response.
4. Fat absorption: lymphatic system absorbs
and transport fatty acids and fats as chyle
to the circulatory system.
7. 5. Lymphatic tissue are involved in the
production of the lymphocytes and plasma
cells.
6. Reticular cells of the lymphocyte filters the
fluids and supply essential nutrients,
oxygen, hormones to the body.
8. TYPES OF LYMPHOID TISSUE
1. Primary lymphoid organ
2. secondary lymphoid organ
3. Tertiary lymphoid organ
9. 1.Primary lymphoid organ
It is the area where pre T and pre B
lymphocytes gets mature.
Eg: thymus and Bone marrow
Thymus arises from an outgrowth of third
pharyngeal pouch.
10. 2. Secondary lymphoid organ
It is a site where lymphocytes interact with
each other and non lymphoid cells to
generate immune responses to antigens.
Eg: spleen, lymph nodes, tonsils, adenoids,
payer’s patches, mucosa associated
lymphoid tissue (MALT) etc.
11. 3. Tertiary lymphoid organs
Tertiary lymphoid organs are the abnormal
accumulation of the lymphocytes in non
lymphoid organ. Mainly imports
lymphocytes during inflammatory response.
Its composition, morphological
organization chemokines are similar to
secondary lymphoid organ.
Eg: cutaneous associated lymphoid
tissue(CALT).
12.
13. LYMPH NODES
Lymph nodes are small nodules of lymphoid
tissue found in course of smaller lymphatic.
The lymph nodes develops in the early fetal
period via a septation of the lymph sacs by
mesenchymal cells. The spaces thus
delimited become the sinus of the adult
lymph nodes.
Numbers : about 800 lymph nodes
14. Structure
Oval or bean shaped scattered throughout the body.
Nodular soft and encapsulated peripheral lymphoid
organ. They show a smooth surface on the outer side
and inner side consists of hilum through which
vessels enters and exits.
Capsule is composed of collagen and elastic fibers
with few fibroblasts.
The gland substance contains outer cortex and inner
medulla.
15. Cortex : outer layer, made up of lymphatic
follicles. Trabeculae arises from cortex to
capsule. The spaces between the trabeculae
contains reticular fibers.
Medulla: central part, contains loosely packed
lymphocytes, plasma cells and macrophages.
Trabeculae divides into numerous septa.
Besides these, reticular cells and reticular fibers
are found.
16.
17.
18. PASSAGE OF LYMPH THROUGH
LYMPH NODE
Afferent lymphatic vessels pour their lymph
into the capsular sinuses, which is placed
just under the capsule and cortical
lymphocytes.
From here the lymph flows deep into the
cortex in trabecular sinuses and reaches
medullary sinuses.
19. The medullary sinuses then drain into and
efferent lymphatic vessels at hilum through
which lymph passes out of lymph node.
The sinuses are lined by endothelium but
their walls allows passage of lymphocytes
into and out of the sinuses.
20. FUNCTION OF LYMPH NODES
Centre for mechanical filtration of foreign
substances in the lymph by phagocytosis.
Acts as a site for antigen presentation.
Lymphocytes activation, differentiation and
proliferation.
Classification of lymph nodes
1. Superficial node
2. Deep node
21. THE SUPERFICIAL LYMPH NODES
The superficial lymph nodes lies above the
investing layer of deep fascia.
They contains few small nodes that lie superficial
to the external jugular and anterior jugular
veins.eg:
Sub mental
Submandibular
Buccal
Parotid(pre-auricular)
Mastoid(retro- auricular/post- auricular)
Occipital
Superficial cervical
22. THE DEEP LYMPH NODES
The upper deep cervical( jugulo- digastrics group)
lie along the upper part of internal jugular vein
deep to the sternomastoid.
The lower deep cervical( jugulo- omohyoid
group)arranged along the lower part of the
intrajugular vein also deep to the sternomastoid
muscles.eg :
Upper deep cervical
Lower deep cervical
Waldyer’s ring
Nodes of midline
23. DRAINAGE AND NODES OF HEAD
AND NECK REGION
Skin of head and neck: Superficial cervical
nodes
Eyelids: Parotid and deeps nodes
External nose and cheeks: Buccal nodes and
submandibular nodes
Lateral part of cheeks: Parotid nodes
Buccal floor and lingual apex: Submental
nodes
24. Deeper tissue of head and neck: Deep cervical
nodes
Anterior part of the floor of the mouth:
Upper deep cervical nodes via submental nodes
Lateral part of the floor of the mouth:
Submandibular and superior deep cervical nodes
Tip of the tongue: Submental lymph nodes
Anterior 2/3rd of the tongue: Submental and
submandibular nodes and then to lower deep
cervical nodes
Posterior 1/3rd the tongue: upper deep cervical
nodes
25. Hard palate: Retropharyngeal and superior
deep cervical nodes
Soft palate: Retropharyngeal and superior
deep cervical nodes
Tonsils: Superior deep cervical nodes and
then to jugulodigastric nodes
Rich submucous lymphatic plexus of
mouth and pharynx: Deep cervical lymph
nodes
Teeth: Submandibular and deep cervical
nodes
Gingiva: Submandibular nodes
28. DRAINAGE OF ORAL STRUCTURES
The node are arranged according to the 7 levels of
neck they are:
Level I : Contains two sub level ie
level IA(sub mental node): all nodes between
margins of anterior digastrics muscles, above
hyoid bone , below mylohyoid muscle.
Level IB( sub mandibular): all nodes below
mylohyoid muscles, above hyoid bone , posterior
and digastrics muscle and submandibular gland.
29. Level II (upper jugular): Also contains two
sublevels
level IIA: All nodes that lies posterior to the
internal jugular vein and inseparable from
the vein or lies anterior , lateral or medial to
the vein.
Level IIB: all nodes that lies posterior to
internal jugular vein and have a fat plane
separating the nodes and the vein.
30. Level III (middle jugular): All node between
hyoid bone and cricoid cartilage arch and
anterior to posterior sternocleidomastoid
muscle, and lateral to the internal carotid
artery.
Level IV (lower jugular): All nodes between
cricoid cartilage arch and clavicle , anterior to
posterior sternocleidomastoid muscle and
posteriolateral to anterior scalene muscle and
lateral to common carotid artery.
31. Level V(posterior triangle): contains two
sub level
Level VA : All nodes between skull base and
cricoid cartilage arch, behind posterior edge
of sternocleidomastoid muscle
Level VB: all nodes between cricoid cartilage
arch and clavicle behind
sternocleidomastoid muscle.
32. Level VI( central compartment): All
nodes inferior to hyoid bone and above top
of manibrium, between medial margins of
common carotid and internal carotid.
Level VII( superior mediastinal) : All the
node behind the manibrium between
medial margins of bilaterally, extending
inferiorly to level of innominate vein.
33. TONSILS
It is a multiple group of large lymphatic
nodules
Location: mucous membrane of oral and
pharyngeal cavities.
Function: to produce lymphocytes and
immunological response against the antigens
in contact with epithelium.
Structure
Externally covered by capsule and underlined
mucous or serum mucosa associated gland.
34. TYPES OF TONSIL
1.Lingual tonsil
Paired, located at the base of the tongue ie
extended from the circumvallated papillae
to base of the epiglottis.
Made up of bunch of non branching crypts.
Capsule is covered by non keratinized
stratified squamous epithelium.
35. 2.Pharyngeal tonsil/ adenoids
Single tonsillar tissue with no crypts but has
many folds in the mucosa. Located in
posterior wall of nasopharynx.
No well defined lymphyoid nodules
Epithelium covering the tonsil is pseudo
stratified squamous epithelium.
Drains to retro pharyngeal nodes.
36. 3. palatine tonsil
Located at posterior lateral walls of
oropharynx
Largest tonsil in waldeyer’s ring
Divided into lobules by the crypts
Contains of aggregation of lymphatic
nodules within the diffuse lymphoid tissue.
This tonsil has only afferent lymphatic
vessels.
37. WALDEYER’S RING
Thus to protect the oropharynx the tonsil
form a lymphatic tissue in ring called as
Waldeyer’s ring.
Posterior and above nasopharyngeal tonsil
laterally and above the root of pharynx.
Inferiorly lingual tonsil over the posterior
part of the dorsum of the tongue.
38. CLINICAL CONSIDERATIONS
SENTINAL LYMPH NODE
Hypothetical first lymph node or group of nodes
draining a cancer. Postulated that these nodes are
the target organ primarily raised by metastasizing
cancer cells from the tumor.
TONSILLITIS
It is an inflammation of palatine tonsil ,common in
children caused by virus or by bacterial infection
like strep throat. with symptoms like sore throat,
fever and swollen tonsil.
39. Lymphadenitis
It is the enlargement of the lymph node
caused by viral bacterial or fungal
infections.
40. Metastasis
Carcinomas metastasize by lymphatic
route.
The wall of lymphatic is readily invaded by
cancer cells and forms a continuous growth
in lymphatic channels called as lymphatic
permeation, or may detach to form tumor
emboli to be carried along to the next lymph
node.
41. CONCLUSION
The lymphatic system in the human body
has a subtle very vital function to play. The
system performs the role of tissue drainage
along with protection by activation of the
defense cells of the body. The former role
helps in maintaining the blood volume and
the latter helps in defense and building up
of immunity.
42. REFERENCE
ORBAN’S ORAL HISTOLOGY AND
EMBRYOLOGY 14TH EDITION
BD CHAURASIA’S HANDBOOK OF
GENERAL ANATOMY
43. MCQ’S
1. Adenoids is an example of:
a. Primary lymphoid organ
b. Secondary lymphoid organ
c. Tertiary lymphoid organ
d. Central lymphoid organ
44. 2. Level I area of neck includes which lymph
nodes?
a) Submental and submandibular nodes
b) Sub mental and parotid nodes
c) Sub mandibular and parotid nodes
d) Parotid and cervical nodes
45. 3. Which is the largest tonsil in waldeyer’s
ring?
a. Lingual tonsil
b. Pharyngeal tonsil
c. Adenoids
d. Palatine tonsil
46. 4. Lymphatic drainage of tip of tongue is by:
a) Superficial cervical node
b) Deep cervical node
c) Submental node
d) Parotid node
47. 5. Which is not a secondary lymphoid organ?
a) Payer’s patches
b) Lymph node
c) Spleen
d) Thymus
