OS 206 E1 20131112 Spleen, Pancreas and Small Intestine v2

7/17/2019 OS 206 E1 20131112 Spleen, Pancreas and Small Intestine v2

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TOPIC OUTLINE

I. SpleenA. CharacteristicsB. LigamentsC. Surface FeaturesD. BordersE. VesselsF. Innervation

II. PancreasA. CharacteristicsB. PartsC. VesselsD. InnervationsE. Ducts

III. Small intestineA. CharacteristicsB. Parts

1. Duodenum12 Jejunum and Ileum

I. SPLEEN

A. CHARACTERISTICS

Location• In the left hypochondriac region (left upper

abdominal quadrant) closely related to the leftlung, left pleural cavity, and left ostophrenicrecess

• Under the cover of the left 9th-11th ribs in themidaxillary line

o if the left-side lower ribs and/or upperlumbar transverse processes arefractured, the spleen is also most likelydamaged/ruptured

Fig 1. Anterior View of the Spleen

Fig 2. Lateral View of the Spleen

• Usually not palpable

o in case of hypertrophy/enlargement, doNOT palpate ! possibility of ruptureand can be fatal

• Position assessed by percussion

o Normal: dull area over 9th-11th ribs,

should not go beyond midaxillary lineo Abnormal (i.e. enlargement): dull area

over 9th-10th ribsFunctions

• Prenatal – Hemapoetic organ

• Afterbirth – identifies, removes, and destroysexpende RBC’s and broken down platelets;recylces iron and globin

• Largest lymphatic organ – lymphocyteproliferation and immune response

• Blood reservoir

• Can self-transfuse in times of hemorrhagicstress

Clinical Correlation

• Blunt force trauma to the abdomen (e.g. crushinjury, punch/blow)

•

When diseased, can possibly rupture from mildmechanical stimulation (e.g. palpation)

B. LIGAMENTS

• Attach to the medial aspect of spleen hilum

• Gastrosplenic ligamento From the hilum to the left part of the

greater curvatureo Contains short gastric arteries and left

gastroepiploic artery

• Splenorenal ligamento From the front upper half of the left

kidney to the hilum of spleen

C. SURFACE FEATURES

• Diaphragmatic Surfaceo Convex and smootho Beneath left lead of diaphragm and

adjacent ribs• Visceral Surface

o Gastric Surface

" Upper part of posterior stomach" Adjacent to notch located on

superior bordero Renal Surface

" Lateral upper part of left kidney" Near inferior border, absence

of notch on this side

Fig 3. Surface Impression of the Spleen

• Impressions

o Colic Impression



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" Over phrenocolic ligament andleft flexure of colon

" Supports lower spleeno Pancreatic Impression

" Related to tail of pancreasbelow lateral hilum of spleen

" Forms left boundary ofomentum

D. BORDERS

• Anterior and Superioro Notch in lower thirdo Palpable notch differentiates spleen

enlargement from LUQ tumors

• Posterior (Medial) and Inferioro Smooth and roundedo Separates renal and phrenic surfaces

E. VESSELS Arterial Supply

• Splenic artery – spearates the renal surfacefrom the phrenic surface; originates from theceliac trunk

• Left and right gastroepiploic/gastro-omentalarteries

Fig 4. Arterial Supply of Pancreas, Spleen and Duodenum

Venous Drainage

• Splenic vein

Fig 5. Venous Drainaige of Pancreas, Spleen andDuodenum

Lymphatics

• Splenic hilum - where splenic lymphaticvessesls leave

• Pancreaticosplenic lymph nodes – relate to theposterior and superior boreder of the pancreas

Fig 6. Lymphatic Drainage of Pancreas, Spleen andDuodenum

F. INNERVATION

• Nerves of the spleen (vasomotor) - from thecoeliac nerve plexus distribtued around splenicartery

II. PANCREAS

A. CHARACTERISTICS

• Soft, elongated, lobulated organ

• In epigastric and left hypochondriac regions

• An accessory digestive gland, producingpancreatic juices from acinar cells, and glucagonand insulin from islets og Langerhans

• Retroperitoneal: crosses L1-L2 vertebral bodies

Fig 7. Location of the Pancreas

B. PARTS

• Head

o Expanded part embraced by the C-shapedcurve of the duodenum to the right of thesuperior mesenteric vessels (SMV)

o Fits snugly in the curve of the duodenum " Pancreatic tumor can possibly obstruct

the common bile duct due to pressure onthe 2nd part of the duodenum where thecommon bile duct enters. This presents

as jaundice and chalk-colored stool.



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There may also be referred pain to theipsilateral shoulder, (sub)scapular, and

flank.

o Crossed anteriorly by root of thetransverse mesocolon

o Separated from the body by pancreaticincisures (formed by the SMV)

o Rests posteriorly on inferior vena cava, rightrenal artery and vein, and left renal vein

o Uncinate process (projection from inferior

pancreatic head) extends medially to theleft, posterior to the superior mesentericartery

Fig 8. Parts of Pancreas

• Necko Short (1.5-2 cm)o Overlies SMV, forming a groove

posteriorlyo Anteriorly adjacent to stomach pyloruso Posteriorly, SMV joins splenic vein !

hepatic portal vein

• Bodyo Triangular cross-sectiono Anteriorly covered with peritoneum

and forming part of stomach bedo Posteriorly devoid of peritoneum and

in contact with SMV, aorta, leftsuprarenal gland, left kidney

o Lateral to SMVo Overlies aorta and L2 verterbra, above

transpyloric plane and beneath omentalbursa

• Tailo Anterior to left kidneyo Close to splenic hilum and left colic

flexureo Relatively mobileo Passes between layers of splenorenal

ligament with splenic vessels

C. VESSELS Arterial Supply

• Pancreatic arteries # splenic artery –(forms)! arcades with pancreatic gastroduodenal artery and Superior Mesenteric Artery (SMA)

• Head:o Anterior and posterior

pancreaticoduodenal arteries arebranches of gastroduodenal artery

o Anterior and posterior inferiorpancreaticoduodenal arteries arebranches of SMA

o Shares same blood supply asduodenum (via two arterial arcadesembedded in anterior and posteriorsurface of pancreatic head) , requiring

removal of duodenal part duringpancreatic resection

• Body and Tail:o ~10 splenic artery brancheso Dorsal, inferior, great pancreatic arteries

Venous Drainage

• Pancreatic veins - correspond to pancreaticarteries; tributaries of splenic and superiormesenteric parts

• Mostly empty into splenic vein –(joins)! SMA –(forms)! hepatic portal vein

Fig 9. Venous Drainage of the Pancreas

Lymphatics

• Follow blood vessels

• Most terminate at the pancreaticosplenic lymphnodes lie along splenic artery

• Some terminate at the pyloric lymph nodes

• Drain into superior mesenteric lymph nodes orcoeliac lymph nodes (via hepatic lymph nodes)

D. INNERVATION

• From CN X and abdominopelvic splanchnic

nerves

• Parasympathetic and sympathetic fibers reach

pancreas by passing along the arteries fromceliac plexus and superior mesenteric plexus;also distributed to pancreatic acinar cells andislets

• Parasympathetic fibers: secretomotor, butpancreatic secretion is primarily mediated bysecretin and cholecystokinin (formed by epithelialcells of duodenum and upper intestinal mucosa;stimulated by acid contents

E. DUCTS



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Fig 10. Ducts of Pancreas with related structures

• Duct of Wirsung (Main Pancreatic Duct)o Runs the length of the pancreas

collecting radicles from the entire bodyand tail from the posteroinferior part of

the head including the uncinate process

o Begins in the tail and runs through theparenchyma of the gland to thepancreatic head where it turns inferiorlyand is closely related to the commonbile duct

o Ampulla of Vater# duct of Wirsung +common bile duct

• Duct of Santorini (Minor Pancreatic Duct)o 2 cm superior to main ducto Drains anterosuperior part of the heado Opens into the descending (or 2

nd ) part

of the duodenum at the summit of minorduodenal papilla

o Usually communicates with the mainpancreatic duct (60% of the time)

o Sometimes larger than the mainpancreatic duct and not connected to it

" fusion or lack thereof duringpancreatic developmentexplains variations of the ducts

Clinical Correlations

• Carcinoma of the head of the pancreas usuallyshows itself by painless progressive jaundice anddistention of the gallbladder due to compressionof the common biliary duct

o Compresses and obstructs bile ductand/or hepatopancreatic ampulla

o Effects: Causes: Obstruction,enlargement of gallbladder, and

jaundice (obstructive jaundice)

• 90% of people with pancreatic cancer haveductular adenocarcinoma

•

Carcinoma involving the neck and body involvesportal or IVC obstruction

III. SMALL INTESTINES

A. CHARACTERISTICS

• Site of digestion and food absorption

• 6-7 m long

• From pylorus to ileocecal valve

• Jejunum and ileum: long greatly coiled partsattached to the posterior abdominal wall bymesentery

o jejunum: proximal 2/5o ileum: distal 3/5

B. PARTS

Fig 11. Parts of Duodenum

1. Duodenum

• 20-25 cm long

• First part of the small intestine

•

Shortest, widest, and most sessile part of thesmall intestine

• No mesentery; partially covered by the

peritoneum

• Curves in a “C” around the head of the pancreas

4 PARTS

1st Part/Superior Duodenum

• 5 cm long; extends from the pylorus to the neck

• Most movable of all parts

• Anteriorly covered by peritoneum but bareposteriorly (except near pylorus)

• Relations:

o Anteriorly: quadrate lobe of liver andgallbladder

o Posteriorly: lesser sac, gastroduodenalartery, bile duct, portal vein, IVC

o Superiorly: epiploic forameno Inferiorly: head of pancreas

2nd Part/Descending Duodenum

• 8-10 cm long

• from the neck of the gallbladder to the lowerborder of L3 vertebra

• Relations:o Anteriorly: gall bladder, fundus, right

lobe of liver, tranverse colon, coils ofsmall intestine

o Posteriorly: hilum of right kidney andright ureter

o Laterally: ascending colon, right colicflexure, right lobe of liver

o Medially: head of pancreas, bile ductand main pancreatic duct

3rd Part/Horizontal Duodenum

• 10 cm long

• crossed by SMV

• runs horizontally to the left of the subcostal plane

• begins at the lower border of the L3 vertebra and

ascends at the 4th part in front of the abdominal

aorta

4th Part/Ascending Duodenum

• 2.5 cm long

• ascends to the level of upper border of the leftsuspensory ligament of Treizt (which is attachedto the right crus of diaphragm)



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• marked peritoneal fold from the diaphragm toduodenal termination

Relations:

• Anteriorly: beginning of mesentery root and coilsof jejunum

• Posteriorly: left margin of aorta and medial borderof psoas muscle

CLINICAL

• Radiologically, after a barium meal, the superiorpart appears as a triangular homogenousshadow, known as the duodenal cap

• Plicae circulares (valves of Kerkring) orcircular folds appear about 2.5 to 5 cm from thepylorus, which are large crescentic folds whichproject into the intestinal lumen

ARTERIAL SUPPLY

• 1st

par t: Supraduodenal, retroduodenal, andduodenal branches from the right gastric, rightgastroepiploic, andgastroduodenal/pancreaticoduodenal arteries

• 2nd

-4th

parts: two arterial arcadesVENOUS DRAINAGE

• Superior pancreaticoduodenal vein ! portal vein

• Inferior vein ! superior mesenteric vein

LYMPHATICS

• Upward: lymph vessels ! pancreaticoduodenalnodes ! gastroduodenal nodes ! coeliac nodes

• Downward: lymph vessels ! pancreaticoduodenal nodes! superiormesenteric nodes

INNERVATION

• Sympathetic and vagus nerves from celiac andsuperior mesenteric plexuses

2. JEJUNUM AND ILEUM

• Attached to the posterior abdominal wall by a fan-shaped fold of peritoneum called the mesenteryof the small intestine

• Root of the mesentery permits the entrance andexit of the branches of the superior mesentericartery and vein, lymph vessels, and nerves intothe space between the two layers

DIFFERENCES:

Proximal Jejunum (2/5) Distal Ileum (3/5)

In upper part ofperitoneal cavity, below

left side of thetransverse mesocolon

In lower part ofperitoneal cavity

and in pelvis

Wider, thicker, heavier(because of morenumerous plicaecircularis), redder

intestinal wall

Narrower, thinner,lighter (because of

very small or absentplicae circularis), paler

intestinal wall

Mesentery attachmentin posterior abdominalwall above and to the

left of the aorta

Mesentery attachmentin posterior abdominalwall below and to the

right of the aorta

Form only 1 or 2

arcades of mesentericarteries

3 or more arcades ofmesenteric arteries

Less fat in mesenteryPresence of

translucent areasFat deposited near theroot and scanty near

the intestinal wall

Abundant mesenteryfat

Laden and opaqueUniform deposition of

fat, extending from rootto wall

No Peyer’s PatchesPresence of Peyer’s

Patches

More folds Less folds

More vascular (redder) Less vascular (paler)

• Caliber of the small intestine diminishes as does

the thickness of its muscular wall from theproximal jejunum to the distal ileum

• Peyer’s patches are visible and often palpableon the antimesenteric border of the ileum

• The mesentery of the proximal small bowel isthinner and contains less fat between its leavesand is more translucent than the mesentery ofthe distal small bowel

• There is more of a marked tendency towardarborization and anastomosis of arterial andvenous arcades in the mesentery of the distalileum than in the mesentery of the proximal

jejunum

ARTERIAL SUPPLY

• Branches of SMA

• Intestinal branches ! gut (anastomose to formarcades)

• Ileocolic artery! lowest part of ileumVENOUS DRAINAGE

• correspond to branches of SMA

• drain into superior mesenteric veinLYMPHATICS

• Lymph vessels ! intermediate nodes ! superiormesenteric nodes

INNERVATION

• Sympathetic and vagus nerves from superiormesenteric plexus

CLINICAL

• Although trauma to the jejunum and ileum iscommon, the injury is less serious compared totrauma in the duodenum. This is because theyare able to move freely, reducing crushing impactfrom blunt trauma. Penetrating injuries may self-seal through mucosal plugging.

• Mesenteric arterial occlusion – the superiormesenteric artery supplies an extensive portionof the gut. An occlusion as the result of embolus,thrombus, aortic dissection, or abdominalaneurysm results in death of all or part of the gutfrom the duodenum to the left colic flexure.

End of Transcription

Aldwin: Hello sa mga anatomates ko, sa Sigma Row 7 & 8

at sa A-Band! :D

Almira: Sorry di ako nakalagay ng message sa initial copy.=]] Umm!hello? Also, advanced happy birthday to

Andrea Contreras (11-19)! =D

Documents

OS 206 E1 20131112 Spleen, Pancreas and Small Intestine v2