07.Lymphatic Sysytem 18

8/3/2019 07.Lymphatic Sysytem 18

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LYMPAHTIC SYSTEMLYMPH, LYMPHATICS AND ORGANS


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LYMPHATIC SYSTEM

The lymphatic system, consisting of lymphatic vessels and variouslymphoid tissues and organs, helps maintain fluid balance in tissues andabsorb fats from the gastrointestinal tract. It also is part of the bodysdefense system against disease.

The lymphatic system is closely related to the circulatory system,both structurally and functionally. A network of lymphatic vessels drains

excess interstitial fluid (the approximate

15% that has not been returned directly to the capillaries) and returns itto the bloodstream in a one-way flow that moves slowly toward thesubclavian veins. Additionally, the lymphatic system functions in fatabsorption and in the bodys defense against microorganisms and otherforeign substances.

In short, the lymphatic system has three principal functions.

It transports excess interstitial (tissue) fluid, which was initially formedas a blood filtrate, back to the blood.

It serves as the route by which absorbed fats and some vitamins aretransported from the small intestine to the blood.

Its cells (called lymphocytes), located in lymphatic tissues, help provideimmunological defenses against disease causing agents.


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FIGURE:The schematic relationship between the circulatory & lymphatic systems.Interstitial (tissue) fluid is an extract of blood plasma formed at the pulmonary &systemic capillary networks. Lymph is the interstitial fluid that enters the lymphaticcapillaries to be transported by lymphatic vessels to the venous bloodstream.

LYMPH AND LYMPHATIC VESSELS

The lymphatic network of vessels begins with the microscopiclymphatic capillaries. Lymphatic capillaries are closed-ended mosttissues. Within the villi of the small intestine, for example, lymphaticcapillaries called lacteals, transport the products of fat absorption away

from the GI tract. Because the walls of lymphatic capillaries are composedof endothelial cells with porous junctions, interstitial fluid, proteins,microorganisms, and absorbed fats (in the small intestine) can easilyenter. Once fluid enters the lymphatic capillaries, it is referred to aslymph. Adequate lymphatic drainage is needed to prevent theaccumulation of interstitial fluid, a condition called edema.

From merging lymphatic capillaries, the lymph is carried into largerlymphatic vessels called lymph ducts.The walls of lymph ducts are muchlike those of veins. They have the same three layers and also containvalves to prevent backflow. The pressure that keeps the lymph moving

comes from the massaging action produced by skeletal musclecontractions and intestinal movements, and from peristaltic contractions


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of some lymphatic vessels. The valves keep the lymph moving in onedirection.

FIGURE:A Photomicrograph of valve (arrow) within a lymph vessel.

Interconnecting lymph ducts eventually empty into one of the twoprincipal vessels: the thoracic ductand the right lymphatic duct. Thelarger thoracic duct drains lymph from the lower extremities, abdomen,left thoracic region, left upper extremity, and left side of the head andneck. The main trunk of this vessel ascends along the spinal column anddrains into the left subclavian vein. In the abdominal area, there is asaclike enlargement of the thoracic duct called the cisterna chyli, whichcollects lymph from the lower extremities and the intestinal region.

The smaller right lymphatic duct drains lymphatic vessels from theright upper extremity, right thoracic region, and right side of the head and

neck. The right lymphatic duct empties into the right subclavian vein nearthe internal jugular vein.


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FIGURE:The Lymphatic system showing the principal lymph nodes andother lymphoid organs. Lymph from the upper right extremity. The right side of the headand neck, and the right thoracic region drains through the right lymphatic duct into theright subclavian vein. Lymph from the remainder of the body drains through the thoracicduct into the left subclavian vein.


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LYMPH NODES


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FIGURE:The Structure of a Lymph node. (a) A photograph of a lymph node positionednear a blood vessel, (b) a diagram of a sectioned lymph node and associated vessels and(c) a photomicrograph of a lymph node.

Lymph filters through the reticular tissue of hundreds of lymphnodesclustered along the lymphatic vessels. The reticular tissue containsphagocytic cells that help purify the fluid. Lymph nodes are small bean-shaped bodies enclosed within fibrous connective tissue capsules.

Specialized connective tissue bands called trabeculae divide thenode.Afferent lymphatic vessels carry lymph into the node, where it is

circulated through the sinuses, a series of irregular channels. Lymphleaves the node through the efferent lymphatic vessel, which emergesfrom the hiluma depression on the concave side of the node. Lymphaticnoduleswithin the node are the sites of lymphocyte production, and arethus important in the development of an immune response.

Lymph nodes usually occur in clusters in specific regions of thebody. Some of the principal groups of lymph nodes are the poplitealandinguinal nodesof the lower extremity, the lumbar nodes of the pelvicregion, the cubital and axillary nodes of the upper extremity, the thoracicnodes of the chest, and the cervical nodes of the neck. The sub mucosa of

the small intestine contains numerous scattered lymphocytes andlymphatic nodules, and larger clusters of lymphatic tissue calledmesenteric (Peyers) patches.

OTHER LYMPHOID ORGANS

In addition to the lymph nodes just described, the tonsils, spleen,and thymus are lymphoid organs.

TONSILS

The tonsilsform a protectivering of lymphatic tissue around theopenings between the nasaland oral cavities and the pharynx.

SPLEEN

The spleenis located on the left side of the abdominal cavity, to theleft of the stomach from which it is suspended. The spleen is not a vitalorgan in an adult, but it does assist other body organs in producinglymphocytes, filtering the blood, and destroying old erythrocytes. In aninfant, the spleen is an important site for the production of erythrocytes.

In an adult, it contains redpulp, which serves to destroy old erythrocytes,


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and white pulp, which contains germinal centers for the production oflymphocytes.

THYMUS

The thymusis located in the anterior thorax, deep to themanubrium of the sternum. Because it regresses in size during puberty, itis much larger in a fetus and child than in an adult. The thymus plays akey role in the immune system.


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FIGURE:The structure of the spleen (a) A medial view, (b) A diagram of the pulp, and(c) a photomicrograph (10x)

FIGURE:The Thymus is located in the mediastinum, medial to the lungs.

The lymphoid organs are summarized in table below.

LYMPHOID ORGANS

ORGAN LOCATION FUNCTION

Lymph

Nodes

In clusters or chains

along the paths of larger

lymphatic vessels

Sites of lymphocyte production;

house T lymphocytes and B

lymphocytes that are responsiblefor immunity; phagocytes filter

foreign particles and cellular debris

from lymph.

Tonsils In a ring at the junction

of the oral cavity and

pharynx

Protect against invasion of foreign

substances that are ingested or

inhaled.

Spleen In upper left portion of

abdominal cavity,beneath the diaphragm

Serves as blood reservoir;

phagocytes filter foreign particles,cellular debris, and worn


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and suspended from thestomach

erythrocytes from the blood;houses lymphocytes

Thymus Within the mediastinum,

behind the manubrium

Important site of immunity in a

child; houses lymphocytes;

changes undifferentiated

lymphocytes into T lymphocytes

THORACIC DUCT

DEFINITION: It is the largest and elongated common lymphatic channel,

conveys lymph from the whole part of the body into the blood stream

except the -

Right side of head and neck.

Right side of the face.

Right superior extremity

Right side of chest wall

Right lung and Pleura

Right of the heart and pericardium

Right dome of the diaphragm

Right surface of the liver

LENGTH: 38 to 45 cm

BREADTH: 0.5 CM ( at its origin)

BEGINNING: Thoracic duct starts as an upward continuation of cisterna

chyle, which is situated infront of the bodies of L1 & L2 vertebrae.

Vertebral Level At the lower border of T12 vertebrae.

END: It ends in the left Brachiocephalic vein at the site of its formation,

behind the left sterno clavicular joint.

VARIATIONS IN TERMINATION:


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1) Sometimes thoracic duct divides into a number of new vesselswhich ends separately into the left internal jugular and left

subclavian veins.

2) Occasionally, the duct divides in the mid thoracic region where the

right duct opens at the junction of right internal jugular and right

subclavian veins after joining with the right lymphatic duct and left

duct ends at the junction of left internal jugular and left subclavian

vein.

3) The duct may terminate into either of the great veins.

COURSE

1) After its origin, it enters into the thorax through the aortic opening

of the diaphragm.

2) Then, it ascends upwards behind the oesophagus in the posterior

mediastinum of the thorax.

3) At the level of T5 vertebra the duct inclines to the left.

4) Then, it further ascends upwards through the superior mediastinum

along the left margin of the oesophagus.

5) At the root of the neck the duct arches laterally opposite the

transverse process of C7 vertebrae.6) Finally, the duct turns downwards to terminate usually, at the

junction of left internal jugular vein and left subclavian vein.

CHARACTERISTICS OF THE THORACIC DUCT

I. It is flexible in character.

II. Beaded in appearance.

III. It has many valves on those sides which are exposed to pressure.

RELATIONS

1. AT THE AORTIC OPENING:

INFRONT Median Arcuate ligament.

BEHIND TV 12

ON THE RIGHT Azygos vein

ON THE LEFT Aorta

2. IN THE POSTERIOR MEDIASTINUM

INFRONT

Posterior sloping surface of the diaphragm


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Oesophagus Right pleural recess.

BEHIND

T5 to T12 vertebrae with their intervertebral discs and

anterior longitudinal ligament.

Terminal parts of accessory Azygos and Hemiazygos veins.

Right posterior intercostal arteries.

ON THE RIGHT SIDE -

1) Azygos vein2) Right Splanchnic nerves

3) Right Sympathetic trunk

4) Right Lung and Pleura

ON THE LEFT SIDE -

1) Descending thoracic aorta.

2) Hemiazygos vein

3) Left Splanchnic Nerves

3. IN THE SUPERIOR MEDIASTINUM

INFRONT

1) Arch of Aorta

2) Left subclavian artery

BEHIND T1 to T4 vertebrae with intervertebral discs and anterior

longitudinal ligament.

ON THE RIGHT SIDE - Oesophagus

ON THE LEFT SIDE Left lung and pleura

4. AT THE ROOT OF THE NECK

INFRONT Left carotid sheath containing Left internal jugular vein,

Left common carotid artery, Left vagus nerve. (Artery medially, vein

laterally and nerve between and behind them)

BEHIND

a. Left sympathetic trunk with inferior cervical ganglion.

b. Vertebral artery and vein

c. Thyro cervical trunk and its branches.i. Inferior thyroid artery.


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ii.Transverse cervical artery.iii.Suprascapular artery.

d. Left phrenic nerve

e. Left Scalenus anterior muscle

f. Left subclavian artery (1st part)

TRIBUTARIES

1) Confluence of lymph trunk (Cisterna Chyle)

2) Descending thoracic lymph trunks from the lower 6 or 7 intercostal

spaces of both sides.

3) Ascending lumbar lymph trunks from the upper lateral aortic lymph

nodes.

4) Upper intercostal trunks from upper 5 or 6 left intercostal spaces.

5) Mediastinal trunks from the convex diaphragmatic aspect of the

liver, the pericardium, heart and oesophagus.

6) Left subclavian trunk (usually) but may drain into the left subclavian

vein.

7) Left Jugular trunk (usually) but may drain into the left internal

jugular vein.

8) Left broncho mediastinal trunk (occasionally).


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FIGURE:The course of the thoracic duct.

LYMPHATIC DRAINAGE OF BREAST

INTRODUCTION: Lymphatic drainage of the mammary gland are dividedinto 3 ways. They are

I. Lymphatics of the parenchyma of the breast and also from the skinof the Nipple and Areola.

II. From the skin except Nipple and the Areola.III. From the Stroma

I. LYMPHATICS OF THE PARENCHYMA OF THE BREAST AND ALSO

FROM THE SKIN OF THE NIPPLE & THE AREOLA:

1. These originate in a plexiform network from the interlobular spacesand walls of the lactiferous ducts and ends into the sappeys plexussituated beneath the nipple and areola.

Sappeys plexus also receives lymph from the nipple and theareola.

2. Some of the lymphatics run deeper along the ligaments of cooper todrain into the lymphatic lake of Haller situated on the fasciacovering the pectoralis major.

From the lymphatic lake of Haller lymph vessels are drain into thefollowing directions:

a. From the upper part ends in the apical group of axillary lymphnodes.

b. From the Lower and Lateral part ends in the pectoral group oflymph nodes to the Anterior abdominal parietes.

c. From the Upper and Lateral part ends in pectoral group of theaxillary lymph nodes.

d. From the Lower and medial part ends in the sternal lymph nodes ofthe same side and some joining with the lymphatics of the oppositesides. Some drains into the mediastinal group of lymph nodes.

e. From upper and medial part drains into the sternal lymph nodes ofthe same and opposite sides.

f. From the lowest part of the medial area pass through the lymphplexus in the rectus sheath then pass along the falciform ligamentto the hepatic lymph nodes. This is the dangerous area.

II. FROM THE SKIN EXCEPT NIPPLE AND THE AREOLA.

Lymphatics drain in the following ways:


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a. From the upper marginal area. A) Apical group of Axillary lymphnodes.

B) Infra clavicular lymph nodes.

b. From the upper and lateral areas including axillary tail ends in thepectoral group of the Axillary lymph nodes.

c. Lower and Lateral area ends in the A) Pectoral group of axillarylymph nodes.

B) To the anterior abdominal parietesd. Medial area ends in the sternal group of lymph nodes at the same

and opposite side runs along the internal mammary artery.

III. FROM THE STROMA

SUPERFICIAL PART Along the lymphatics of the skin

DEEP Along the lymphatics of the glandular tissue. Axillary lymph nodesreceive more than 75% of the lymph from the mammary gland.


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FIGURE:The Lymphatic drainage of the breast.

FIGURE:The Lymphatic drainage of the breast.

AXILLARY LYMPH NODES

DEFINATION: Axillary lymph nodes carry the lymph from the wholeupper limb, the breast and from the body. (From the umbilicus to theclavicle)

NUMBER OF LYMPH NODES: 20 TO 30 in number.

DIVISION:

I. ANTERIOR OR PECTORAL GROUP

SITUATION Along the lower border of the pectoralis minor near thelateral thoracic vessels

NUMBER 4 or 5 in number

AFFERENTS (RECEIVE)

1. From the skin and muscle of supraumblical and Anterolateral part ofthe body wall.

2. From the lateral part of the breast.

EFFERENTS (DRAIN)

1. Partly to the apical axillary nodes.2. Partly to the central axillary nodes

II. POSTERIOR OR SUBSCAPULAR GROUP


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SITUATION Inferior margin of the posterior Axillary wall, Along thesubscapular vessels.


AFFERENTS (RECEIVE) From the skin and muscles of the

1. Lower part of the back of the neck.2. Dorsal aspect of the trunk down to the iliac crest.

EFFERENTS (DRAIN) Apical and central axillary nodes.

III. LATERAL GROUP

SITUATION Posteromedially to the axillary veinNUMBER 4 to 6 in number

AFFERENTS (RECEIVE) Whole upper limb except those going alongthe cephalic vein.

EFFERENTS (DRAIN)

1. Partly to the central and apical axillary groups.2. Partly to the lower deep cervical lymph nodes.

IV. CENTRAL GROUP

SITUATION It is embedded in Axillary fat.


AFFERENTS (RECEIVE) From all preceding groups (Anterior, Posterior,Lateral)

EFFERENTS (DRAIN) Drain to the apical nodes.

V. APICAL GROUP

SITUATION Deep to the clavipectoral fascia along the axillary vessels

extending to the apex of the axilla.

NUMBER 6 to 12 in number.

AFFERENTS (RECEIVE)

1. Directly some of the lymph vessels accompany the cephalic vein.2. From the mammary gland.3. From the Anterior, Posterior, Lateral and central group of axillary

lymph nodes.

EFFERENTS (DRAIN)

1. Its afferents unite to form subclavian lymph trunk and drains intoany of the followings


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a. At the site of formation of Brachiocephalic vein.b. Subclavian veinc. Jugular lymphatic trunkd. Right Lymphatic duct (Right side)e. Thoracic duct (Left side)

2. Few efferent usually ends in the inferior deep cervical nodes.

FIGURE:The lymph nodes of the axilla

INGUINAL LYMPH NODES

DEFINATION: The inguinal lymph nodes are situated immediately belowthe inguinal ligament. They mostly carry lymph from lower limb eitherdirectly or indirectly through the popliteal and anterior tibial nodes.

CLASSIFICATION:

Superficial Inguinal Lymph NodesDeep Inguinal Lymph Nodes


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I. SUPERFICIAL INGUINAL LYMPH NODESSITUATION Mostly over the fascia late.

They are further divided into:

1. PROXIMAL OR HORIZONTAL SET:

SITUATION Immediately below and parallel to the inguinal ligament.

NUMBER 5 or 6 in number.

These groups further consist of:

A. LATERAL GROUP:

AFFERENTS (RECEIVE): Buttock, Lateral part of Lower ofAbdomen, Below the umbilicus.

B. MEDIAL GROUP

AFFERENTS (RECEIVE):

a. Skin of the penisb. Scrotumc. Perineumd. Mucous membrane of the anterior part of the Urethrae. Anal canal

f. Medial of the lower part of the Abdomen below theumbilicus

g. Lymph vessels which accompanying the round ligament ofuterus (female)

h. Labia majora (Female)i. Lower part of the Vagina (Female)

2. DISTAL OR VERTICAL SET:

SITUATION Along the upper end of the Great Saphenous vein.

NUMBER 4 to 5 in number.

AFFERENTS (RECEIVE)

a. Skin and fascia of the lower limb, except the buttock and the shortsaphenous tributaries.

b. Few lymphatics from the accompany the short saphenous vein.

EFFERENTS (DRAIN) - All superficial inguinal lymph nodes drain into theexternal iliac group of lymph nodes some into the deep inguinal lymphnodes.

II. DEEP INGUINAL LYMPH NODES

SITUATION Beneath the fascia lata on the medial to the upper part ofthe femoral vein.


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NUMBER 2 to 3 in number (most proximal mode of the group in femoralcanal called CLOQUETS lymph node.

AFFERENTS (RECEIVE) Superficial inguinal nodes.

Popliteal nodes Glans penis (or) clitoris Deep lymphatics accompany the femoral vein

EFFERENTS (DRAIN) External iliac group of lymph nodes.

FIGURE:The inguinal lymph nodes.

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