normal structure of lymph nodes & their distribution
TRANSCRIPT
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
1/33
NORMAL STRUCTURE OF LYMPHNORMAL STRUCTURE OF LYMPHNODES & THEIR DISTRIBUTION INNODES & THEIR DISTRIBUTION IN
THE HEAD & NECK REGIONTHE HEAD & NECK REGION
DR. MANASA RAVATH .C.J.DEPARTMENT OF ORAL &
MAXILLOFACIAL PATHOLOGY
RAJARAJESWARI DENTAL
COLLEGE & HOSPITAL
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
2/33
OUTLINEOUTLINE
y
Introductiony Lymph nodes
* Structure
- stromal component
- lymphoid component
*Vascularization of nodes
*Histophysiology
*Functions*Clinical correlations
Distribution in H &N region
References
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
3/33
INTRODUCTIONINTRODUCTIONy The lymphatic tissue is the second type of
hematopoietic tissuey Broadly classified as
Central Peripheral
( primary) (secondary)
- New lymphocytes - lymphocytes
autonomously produced respond to Ag- Bone marrow - lymph nodes,
- Thymus - spleen, tonsils
- MALT, GALT etc.,
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
4/33
GENERAL ASPECTSGENERAL ASPECTSLymph originates as the surplus tissue fluid
Collected in lymphatic capillaries
Anastomosing system of lymphatics
Thoracic duct & right lymphatic duct
Open into junction b/n the subclavian & IJV
Lymph returned to bloodstream
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
5/33
LYMPH NODESLYMPH NODES
y Small, encapsulated, kidney shaped structures,
up to 2 3 cm longy Distributed along the course of major
tributaries
y Act as filtersfor removal of bacteria & other
foreign antigens
y Most numerous in the neck, axilla, groin,
along major vessels & in the body cavities
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
6/33
STRUCTURESTRUCTURE
y Vary both in shape & size
y Most of them being bean/ kidney shaped
y Broadly described under:
stromalcomponent lymphoid component
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
7/33
THE STROMAL COMPONENTTHE STROMAL COMPONENT
y Each node surrounded by a dense fibrous
capsule, usually surrounded by adipose
tissue
y Convex surface perforated by affarentlymphatics
y Concave surface hilum
- entry and exit of arteries & veins- exit of efferent lymphatics
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
8/33
y Capsule is thickest at the hilum
y Extensions into the substance of the node
called trabeculae
y From both the convex & concave surfaces
y Provide support & convey blood vessels
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
9/33
Lymph from affarent lymphatics
Subcapsular sinus
Cortical sinuses/ paratrabecular sinuses
Medullary sinuses
Efferent lymphatics
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
10/33
CELLS & LINING OF THECELLS & LINING OF THE
SINUSESSINUSESy A layer of simple squamous endothelium
y Have a network of stellate reticulum
y Macrophages attached to stellate cellsy Dendritic cells / dendritic reticular cells
> pale staining
> non phagocytic
> retain foreign antigens on their surface
> present them to T lymphocytes
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
11/33
THE LYMPHATIC COMPONENTTHE LYMPHATIC COMPONENT
CORTEX MEDULLA
PRIMARYNODULES
SECONDARYNODULES
MEDULLARYCORDS
MEDULLARYSINUSES
GERMINAL CENTRES
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
12/33
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
13/33
CORTEX & MEDULLACORTEX & MEDULLA
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
14/33
PRIMARY & SECONDARY NODULESPRIMARY & SECONDARY NODULES
y PRIMARYNODULES:Spherical aggregates of B lymphocytes
SECONDARYNODULES:
> Have a central pale staining area calledgerminal centres
> B lymphocytes are undergoing active
proliferation> Form due to prolonged or secondary
response to antigen
>Surrounded by follicular mantle
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
15/33
SECONDARY NODULESECONDARY NODULE
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
16/33
PARACORTICAL REGIONPARACORTICAL REGION
yRegion of the lymph node between thecortex & the medulla
yHouses most T cells
yThymus dependent zone of the lymphnode
y Further divided into
mid cortical region
deep cortical region
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
17/33
APCs migrate to paracortical region
Present epitope-MHC II complex to TH cells
TH cells become activated & proliferate
width of the paracortex, extrude deep into
the medulla
Newly formed T cells migrate to the
medullary sinus
Efferent vessels, to the area of Ag activity
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
18/33
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
19/33
HIGH ENDOTHELIAL VESSELSHIGH ENDOTHELIAL VESSELSArteries enter through the hilum, form arterial tree
Fine branches enter cortex, empty into postcapillary venules which have high endothelial lining
Deep cortical region, arch into the cortico -medullary region
Lymphocytes leave the vessels by migrating throughthe cuboidal lining
B cells cortex, T cells - paracortex
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
20/33
MEDULLAMEDULLA
y Medullary cords narrow extensions ofnodules into the medulla
y Subdivided into a no. of wavy columns of
lymphoid cells
y Trabeculae
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
21/33
VASCULARIZATIONVASCULARIZATIONArteries enter at the hilum
Course through medulla within the trabeculae
Lose C.T. sheath, travel within medullary cords
Medullary capillary beds, few reach cortex
Drained by post capillary venules
Larger veins, exit via hilum
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
22/33
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
23/33
HISTOPHYSIOLOGYHISTOPHYSIOLOGY
y Affarent lymphatics outnumber efferent
lymphatics
y Sites of antigen recognition
APCs contact Ag
Follicular dendritic cells trap Ag
Lymphocytes recognize the Ag
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
24/33
Ag recognized & B cell activated
Migrates to primary nodule & proliferates
Forms germinal center secondary nodule
Newly formed cells differentiate into B &
plasma cells
Leave cortex, form medullary cords
10% stay in medulla, rest enter sinuses reach
bone marrow
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
25/33
CLINICAL CORRELATIONSCLINICAL CORRELATIONS
y
Nodes located on the path of lymphaticsy Bacteria or virus particles are trapped
y Become inflammed & very tender
y
Such a node is called buboy Can also be secondary cancer sites
metastasis
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
26/33
DISTRIBUTION OF LYMPH NODESDISTRIBUTION OF LYMPH NODES
IN THE HEAD & NECK REGIONIN THE HEAD & NECK REGION
yThere are up to 300 lymph
nodes in the neckyGenerally grouped into
regional terminal
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
27/33
REGIONAL LYMPH NODESREGIONAL LYMPH NODESy Occipital
y Retro auriculary Parotid
y Buccal
y Submandibulary Submental
y Anterior cervical
y Superficial cervicaly Retropharyngeal
y Laryngeal
y Pretracheal
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
28/33
THE TERMINAL NODESTHE TERMINAL NODES
y Receive all the lymph vessels of the H &N
region either directly or indirectly via one ofthe regional lymph nodes
y Closely related to the carotid sheath, in
particular to the IJVy Is referred to as the deep cervical group
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
29/33
DEEP CERVICAL NODESDEEP CERVICAL NODES
y
Form a chain along the course of the IJV,from the skull to the root of the neck
y Two nodes often referred
to clinically are
jugulodigastric
jugulo-omohyoid
y Efferent vessels join to form
jugularlymphtrunk
y This might drain either into the thoracic
duct/ subclavian trunk/ brachiocephalic vein
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
30/33
CLASSIFICATIONCLASSIFICATION
y Henri Rouvire first classified lymph nodesin 1938
y Based on diagnostic imaging newer systems
have been devisedy Commonly used systems have been devised
by American Academy Of Otolaryngology &
American Joint Committee On Cancer
y Divided into various levels as in surgical
approach
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
31/33
LEVELS OF LYMPH NODES INLEVELS OF LYMPH NODES IN
THE NECKTHE NECKy LEVEL I: Submental and submandibular nodes
LEVEL Ia : submental triangle
LEVEL Ib : submandibular triangle
y LEVEL II : Upper jugular nodes
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
32/33
y LEVEL III : Middle jugular nodes
y LEVEL IV : Lower jugular nodes
y LEVEL V : Posterior triangle group
y LEVEL VI : Anterior compartment group
-
8/8/2019 Normal Structure of Lymph Nodes & Their Distribution
33/33
REFERENCESREFERENCES
y David H. Cormack Hams Histology;Ninth Edition; page no 234 -253
y Leslie P. Gartner Text Book Of Histology;
Third Edition; page no 290 -293y Elaine N. Marieb Human Anatomy &
Physiology; Fourth Edition; page no 748
750
y Richard S. Snell Clinical Anatomy for
Medical Students; Sixth Edition; page no
658 -659