anatomy of spleen and it's applied aspect

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DEPARTMENTAL PRESENTATION OF

ANATOMY

Presentor-Satendra kumar dwivedi

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*SUBJECT*

Anatomy of spleen & its applied aspect

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INTRODUCTIONSpleen(Greek splen and Latin lien) is a lymphatic

organ connected to the blood vascular system. it acts as a filter for blood and plays an important role in the immune responses of the body.

The Spleen develops as part of the vascular system in the part of dorsal mesentery that suspends the developing stomach from the body wall.

The spleen  is an organ found in virtually all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter.

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POSITION

The spleen lies obliquely along the long axis of the 10th rib.Thus it is directed downwards, forward and laterally, making an angle of about 45 degrees with the horizontal plane.

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DIMENSIONS

The spleen is soft , highly vascular and dark purple in

colour.The size and weight of spleen are markedly variable.On an

average the spleen is 1 inch thick, 3 inch broad,5 inch long,7

ounces in weight, and is related to 9th to 11th ribs.

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*LOCATION*The Spleen is a wedge-shaped organ lying mainly

in the left hypochondrium, and partly in the epigastrium, it is wedged in between the funds of the stomach and the diaphragm.

The spleen lies against the diaphragm,in the area of rib 9th,to rib 10th.

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EXTERNAL FEATURESThe spleen has two ends ,three borders and two

surfaces and 2 angles and hilum.TWO ENDS-1 -The anterior or lateral end is expanded and is

more like a border.It is directed downwards and forwards, and reaches the midaxillary line.

2-The posterir or medial end is rounded.it is directed upwards,backwards and medially.

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…………EXTERNAL FEATURESThree borders-1-The superior border is charcteristically notched

near the anterior end.2-The inferior border is rounded.3-The intermediate border is also rounded and is

directed to the right.Two surfaces-1.The diaphragmatic surface is convex and smooth.2.The visceral surface is concave and irregular.

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Two Angles-1.Anterobasl angle-It is the junction of superior

border with lateral or anteriror end.2.Posterobasal angle-junction of inferior border

with lateral or anterior end of spleen.Hilum-hilum lies between superior and

intermediate borders it is peirce by branches and tributaries of splenic vessels.

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*RELATIONS*(a)Peritoneal relations(b)Visceral relations Peritoneal relations

The spleen surrounded by peritoneum and is suspended by following ligaments.

1-Gastrosplnic ligament extends from the hilum of the spleen to the greater curvature of the stomach.

2-Lienorenal ligament extends from the hilum of the spleen to the anterior surface of the left kidney.

3-phrenicocolic ligament is not attached to the spleen, but supports its anterior end.

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………….. Relations Visceral RelationsVisceral surface-

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Four impression present are visceral surface of spleen for abdominal organ and other structure-

1.Gastric impression2.Renal impression3.Colic impression4.Pancreatic impressionHilum lies on the inferomedial part of the gastric

impression along the long axis of the spleen.Diaphragmatic surfaceThe surface separates the spleen from the

costodiaphragmatic recess of pleura, lung and 9th ,10th ,11th ribs of the left side.

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Blood supply of the spleenArterial supply-the spleenic artery the largest branch of

coeliac trunk takes tortuous course to the left along the superior border of the pancreas. It travels in the splenorenal ligament and divides in to numerous branches,which enter the hilum of the spleen.As the splenic artery passes along the superior border of the pancreas.It gives off numerous small branches to supply the neck, body and tail of the pancreas.

Approaching the spleeen the splenic artery gives off short gastric arteries,which pass through the gastrosplenic ligament to supply the fundus of the stomach. It also gives off the left gasto-omental artery,which runs to the right along the greater curvature of the stomach and anastomoses with the right gasto-omental artery.

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Venous supplyThe splenic vein is formed at the hilum of the spleen.it runs

a straight course behind the pancreas.it joins the superior mesenteric vein behind the neck of the pancreas to form of portal vein.its tributaries are the short gastric,left gastroepiploic,pancreatic and inferior mesentric veins.

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Histology of spleen

There two main types of tissue in the spleen are specialised for its two main functions:

White pulp contains lymphoid aggregations, mostly lymphocytes, and macrophages which are arranged around the arteries. The lymphocytes are both T (mainly T-helper) and B-cells.

Red pulp is vascular, and has parencyhma and lots of vascular sinuses. These are sinuosoids - a specialised type of capillary, which is very leaky.

The lining endothelial cells have wide slits between their lateral margins, that act as a filter. The blood cells have to move through these slits, before they can leave the spleen and worn out, or defective blood cells are damaged during this process. The damaged cells are then phagocytosed by the numerous macrophages in the red pulp, that lie just next to the sinusoids. The spleen is covered by a dense capsule, and there are connective tissue trabeculae, which provide internal support for the spleen, and carry the blood vessels into the spleen.

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Nerve supply –sympathetic fibres are derived from the coeliac plexus. they are vasomotor in nature. They also supply some smooth muscle present in the capsule.

Functions of spleen-1.Phagocytosis-The spleen is an important component of the

reticuloendothilial system.2.Haemopoiesis-The spleen is an important haemopoietic organ during

life.Lymphopoiesis continues through life.in adult spleen haemopoisis can restart in certain diseases,like chronic

myeloid leukemia and myesclerosis.3.Immuneresponses-Under antigenic stimulation, there occurs

increased lymphopoiesis for cellular responses and incrased formations of plasma cells fo the humoral responses.

4.Storage of RBCs-Red blood cells can be stored in the spleen and released in to the circulation when needed.

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DEVELOPEMENT

Spleen develops in the mesoderm in the cephalic part of left layer of dorsal mesogastrium.The development occurs during sixth week of intrauterine life.Number of nodules develop which soon fuse to form a lobulated spleen notching of the superior border of the adult spleen is an evidence of its multiple origin.

Accessory spleens or Spleniculi-These may be found In the derivatives of the dorsal

mesogastrium i.e. gastrosplenic ligament,lienorenal ligament,gastrophrenic ligament and greater omentum.

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APPLIED ANATOMY

1-Palpation of spleen-A normal spleen is not palpable. An enlarged spleen can be felt under the left costal margin.

2-Splenomegaly-Enlaregement of the spleen is called splenomegaly. sometimes the spleen becomes very large.it then projects towards the right iliac fossa in the direction of the axis of the tenth rib.

3.-Splenctomy-Surgical removal of the spleen is called splenctomy.During this operation damage to tail of the pancreas has to be carefully avoided.

4.-Splenic puncture-Spleen can be punctured through the 9th or 10th intercostal space in the mid axillary line using a lumbar puncture needle.

Intrasplenic presuure is an indirect record of the portal presssure.splenic venography reveals and confirm the enlarged portosystemic communicatiuon in cases of portal hypertention.

Splenic infarction-the smaller branches of splenic artery are end artery.Their obstruction (embolism) result kher’s sign.

Spleen is a danger of trauma to the lower thoracic cage especially 9th, 10th and 11th ribs.

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…..APPLIED ANATOMYPain of splenic tissue is poorly localised.it is also

reffered to the epigastrim region.Stretch of the splenic capsule produces localized pain posteror part of left upper(quadrant).

Partial splenectomy-since there are segmental branches of the splenic artery,only one segment can be removed according to the state of spleen.

After splenectomy ,spleen can be cut in to small pieces and these can be implanted within the greater omentum.

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CLINICAL ANATOMY OF SPLEEN AYUREDA A C