Normal Structure of Lymph Nodes & Their Distribution

8/8/2019 Normal Structure of Lymph Nodes & Their Distribution

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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


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OUTLINEOUTLINE

y

Introductiony Lymph nodes

* Structure

- stromal component

- lymphoid component

*Vascularization of nodes

*Histophysiology

*Functions*Clinical correlations

Distribution in H &N region

References


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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.,


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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


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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


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STRUCTURESTRUCTURE

y Vary both in shape & size

y Most of them being bean/ kidney shaped

y Broadly described under:

stromalcomponent lymphoid component


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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


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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


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Lymph from affarent lymphatics

Subcapsular sinus

Cortical sinuses/ paratrabecular sinuses

Medullary sinuses

Efferent lymphatics


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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


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THE LYMPHATIC COMPONENTTHE LYMPHATIC COMPONENT

CORTEX MEDULLA

PRIMARYNODULES

SECONDARYNODULES

MEDULLARYCORDS

MEDULLARYSINUSES

GERMINAL CENTRES


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CORTEX & MEDULLACORTEX & MEDULLA


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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


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SECONDARY NODULESECONDARY NODULE


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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


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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


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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


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MEDULLAMEDULLA

y Medullary cords narrow extensions ofnodules into the medulla

y Subdivided into a no. of wavy columns of

lymphoid cells

y Trabeculae


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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


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HISTOPHYSIOLOGYHISTOPHYSIOLOGY

y Affarent lymphatics outnumber efferent

lymphatics

y Sites of antigen recognition

APCs contact Ag

Follicular dendritic cells trap Ag

Lymphocytes recognize the Ag


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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


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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


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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


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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


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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


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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


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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


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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


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y LEVEL III : Middle jugular nodes

y LEVEL IV : Lower jugular nodes

y LEVEL V : Posterior triangle group

y LEVEL VI : Anterior compartment group


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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

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Normal Structure of Lymph Nodes & Their Distribution