OS 206 E1 20131112 Spleen, Pancreas and Small Intestine v2

OS  206:  Abdomen  and  Pelvis  

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Duodenum,  Pancreas  and  Spleen   Dr.  G.  Teodosio  

November  12,  2013  

 

 

TOPIC OUTLINE I.

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Spleen A. Characteristics B. Ligaments C. Surface Features D. Borders E. Vessels F. Innervation Pancreas A. Characteristics B. Parts C. Vessels D. Innervations E. Ducts Small intestine A. Characteristics B. Parts 1. Duodenum 2. Jejunum and Ileum   I. SPLEEN

A. CHARACTERISTICS Location • In the left hypochondriac region (left upper abdominal quadrant) closely related to the left lung, left pleural cavity, and left ostophrenic recess • Under the cover of the left 9th-11th ribs in the midaxillary line o if the left-side lower ribs and/or upper lumbar transverse processes are fractured, the spleen is also most likely damaged/ruptured

Usually not palpable o in case of hypertrophy/enlargement, do NOT palpate à possibility of rupture and can be fatal • Position assessed by percussion o Normal: dull area over 9th-11th ribs, should not go beyond midaxillary line o Abnormal (i.e. enlargement): dull area over 9th-10th ribs Functions • Prenatal – Hemapoetic organ • Afterbirth – identifies, removes, and destroys expende RBC’s and broken down platelets; recylces iron and globin • Largest lymphatic organ – lymphocyte proliferation and immune response • Blood reservoir • Can self-transfuse in times of hemorrhagic stress •

Clinical Correlation • Blunt force trauma to the abdomen (e.g. crush injury, punch/blow) • When diseased, can possibly rupture from mild mechanical stimulation (e.g. palpation) • •

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Fig 1. Anterior View of the Spleen

Fig 2. Lateral View of the Spleen •

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B. LIGAMENTS Attach to the medial aspect of spleen hilum Gastrosplenic ligament o From the hilum to the left part of the greater curvature o Contains short gastric arteries and left gastroepiploic artery Splenorenal ligament o From the front upper half of the left kidney to the hilum of spleen C. SURFACE FEATURES Diaphragmatic Surface o Convex and smooth o Beneath left lead of diaphragm and adjacent ribs Visceral Surface o Gastric Surface § Upper part of posterior stomach § Adjacent to notch located on superior border o 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 Page  1  of  5  

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Fig 5. Venous Drainaige of Pancreas, Spleen and Duodenum Lymphatics • Splenic hilum - where splenic lymphatic vessesls leave • Pancreaticosplenic lymph nodes – relate to the posterior and superior boreder of the pancreas

D. BORDERS Anterior and Superior o Notch in lower third o Palpable notch differentiates spleen enlargement from LUQ tumors Posterior (Medial) and Inferior o Smooth and rounded o Separates renal and phrenic surfaces

E. VESSELS Arterial Supply • Splenic artery – spearates the renal surface from the phrenic surface; originates from the celiac trunk • Left and right gastroepiploic/gastro-omental arteries Fig 6. Lymphatic Drainage of Pancreas, Spleen and Duodenum

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F. INNERVATION Nerves of the spleen (vasomotor) - from the coeliac nerve plexus distribtued around splenic artery II. PANCREAS

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A. CHARACTERISTICS Soft, elongated, lobulated organ In epigastric and left hypochondriac regions An accessory digestive gland, producing pancreatic juices from acinar cells, and glucagon and insulin from islets og Langerhans Retroperitoneal: crosses L1-L2 vertebral bodies

Fig 4. Arterial Supply of Pancreas, Spleen and Duodenum Venous Drainage • Splenic vein

Fig 7. Location of the Pancreas

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B. PARTS Head o Expanded part embraced by the C-shaped curve of the duodenum to the right of the superior mesenteric vessels (SMV) o Fits snugly in the curve of the duodenum §

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Pancreatic tumor can possibly obstruct the common bile duct due to pressure on the 2nd part of the duodenum where the common bile duct enters. This presents as jaundice and chalk-colored stool.

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                                                                                                                                                                                      Spleen,  Pancreas   and  Small  Intestine   2018 IA There may also be referred pain to the ipsilateral shoulder, (sub)scapular, and flank.

Crossed anteriorly by root of the transverse mesocolon Separated from the body by pancreatic incisures (formed by the SMV)

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

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Uncinate process (projection from inferior pancreatic head) extends medially to the left, posterior to the superior mesenteric artery

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Neck o o o o

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Body o o o o o

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Short (1.5-2 cm) Overlies SMV, forming a groove posteriorly Anteriorly adjacent to stomach pylorus Posteriorly, SMV joins splenic vein à hepatic portal vein Triangular cross-section Anteriorly covered with peritoneum and forming part of stomach bed Posteriorly devoid of peritoneum and in contact with SMV, aorta, left suprarenal gland, left kidney Lateral to SMV Overlies aorta and L2 verterbra, above transpyloric plane and beneath omental bursa

Tail o o o o

Anterior to left kidney Close to splenic hilum and left colic flexure Relatively mobile Passes between layers of splenorenal ligament with splenic vessels

removal of duodenal part during pancreatic resection Body and Tail: o ~10 splenic artery branches o Dorsal, inferior, great pancreatic arteries

Venous Drainage • Pancreatic veins - correspond to pancreatic arteries; tributaries of splenic and superior mesenteric parts • Mostly empty into splenic vein –(joins)à SMA – (forms)à hepatic portal vein

Fig 9. Venous Drainage of the Pancreas

Fig 8. Parts of Pancreas •

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Lymphatics • Follow blood vessels • Most terminate at the pancreaticosplenic lymph nodes lie along splenic artery • Some terminate at the pyloric lymph nodes • Drain into superior mesenteric lymph nodes or coeliac lymph nodes (via hepatic lymph nodes)

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D. INNERVATION From CN X and abdominopelvic splanchnic nerves Parasympathetic and sympathetic fibers reach pancreas by passing along the arteries from celiac plexus and superior mesenteric plexus; also distributed to pancreatic acinar cells and islets Parasympathetic fibers: secretomotor, but pancreatic secretion is primarily mediated by secretin and cholecystokinin (formed by epithelial cells of duodenum and upper intestinal mucosa; stimulated by acid contents E. DUCTS

C. VESSELS Arterial Supply • Pancreatic arteries ß splenic artery –(forms)à arcades with pancreatic gastroduodenal artery and Superior Mesenteric Artery (SMA) • Head: o Anterior and posterior pancreaticoduodenal arteries are branches of gastroduodenal artery o Anterior and posterior inferior pancreaticoduodenal arteries are branches of SMA o Shares same blood supply as duodenum (via two arterial arcades embedded in anterior and posterior surface of pancreatic head) , requiring Almira,  Aldwin,  Jasmine  

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B. PARTS

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 body and tail from the posteroinferior part of the head including the uncinate process

Begins in the tail and runs through the parenchyma of the gland to the pancreatic head where it turns inferiorly and is closely related to the common bile duct o Ampulla of Vater ß duct of Wirsung + common bile duct • Duct of Santorini (Minor Pancreatic Duct) o 2 cm superior to main duct o Drains anterosuperior part of the head nd o Opens into the descending (or 2 ) part of the duodenum at the summit of minor duodenal papilla o Usually communicates with the main pancreatic duct (60% of the time) o Sometimes larger than the main pancreatic duct and not connected to it § fusion or lack thereof during pancreatic development explains variations of the ducts Clinical Correlations • Carcinoma of the head of the pancreas usually shows itself by painless progressive jaundice and distention of the gallbladder due to compression of the common biliary duct o Compresses and obstructs bile duct and/or hepatopancreatic ampulla o Effects: Causes: Obstruction, enlargement of gallbladder, and jaundice (obstructive jaundice) • 90% of people with pancreatic cancer have ductular adenocarcinoma • Carcinoma involving the neck and body involves portal or IVC obstruction o

III. SMALL INTESTINES

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A. CHARACTERISTICS Site of digestion and food absorption 6-7 m long From pylorus to ileocecal valve Jejunum and ileum: long greatly coiled parts attached to the posterior abdominal wall by mesentery o jejunum: proximal 2/5 o ileum: distal 3/5

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Fig 11. Parts of Duodenum 1. Duodenum • 20-25 cm long • First part of the small intestine • Shortest, widest, and most sessile part of the small 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 bare posteriorly (except near pylorus) • Relations: o Anteriorly: quadrate lobe of liver and gallbladder o Posteriorly: lesser sac, gastroduodenal artery, bile duct, portal vein, IVC o Superiorly: epiploic foramen o Inferiorly: head of pancreas 2nd Part/Descending Duodenum • 8-10 cm long • from the neck of the gallbladder to the lower border of L3 vertebra • Relations: o Anteriorly: gall bladder, fundus, right lobe of liver, tranverse colon, coils of small intestine o Posteriorly: hilum of right kidney and right ureter o Laterally: ascending colon, right colic flexure, right lobe of liver o Medially: head of pancreas, bile duct and 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 th ascends at the 4 part in front of the abdominal aorta 4th Part/Ascending Duodenum • 2.5 cm long • ascends to the level of upper border of the left suspensory ligament of Treizt (which is attached to the right crus of diaphragm) Page  4  of  5  

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marked peritoneal fold from the diaphragm to duodenal termination

Relations: • Anteriorly: beginning of mesentery root and coils of jejunum • Posteriorly: left margin of aorta and medial border of psoas muscle CLINICAL • Radiologically, after a barium meal, the superior part appears as a triangular homogenous shadow, known as the duodenal cap • Plicae circulares (valves of Kerkring) or circular folds appear about 2.5 to 5 cm from the pylorus, which are large crescentic folds which project into the intestinal lumen ARTERIAL SUPPLY st • 1 part: Supraduodenal, retroduodenal, and duodenal branches from the right gastric, right gastroepiploic, and gastroduodenal/pancreaticoduodenal arteries nd th • 2 -4 parts: two arterial arcades VENOUS DRAINAGE • Superior pancreaticoduodenal vein à portal vein • Inferior vein à superior mesenteric vein LYMPHATICS • Upward: lymph vessels à pancreaticoduodenal nodes à gastroduodenal nodes à coeliac nodes • Downward: lymph vessels à pancreaticoduodenal nodes à superior mesenteric nodes INNERVATION • Sympathetic and vagus nerves from celiac and superior mesenteric plexuses 2. JEJUNUM AND ILEUM • Attached to the posterior abdominal wall by a fanshaped fold of peritoneum called the mesentery of the small intestine • Root of the mesentery permits the entrance and exit of the branches of the superior mesenteric artery and vein, lymph vessels, and nerves into the space between the two layers DIFFERENCES: Proximal Jejunum (2/5) In upper part of peritoneal cavity, below left side of the transverse mesocolon Wider, thicker, heavier (because of more numerous plicae circularis), redder intestinal wall Mesentery attachment in posterior abdominal wall above and to the left of the aorta Form only 1 or 2 arcades of mesenteric arteries Less fat in mesentery Presence of translucent areas Fat deposited near the root and scanty near the intestinal wall

Distal Ileum (3/5) In lower part of peritoneal cavity and in pelvis

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Peyer’s patches are visible and often palpable on the antimesenteric border of the ileum The mesentery of the proximal small bowel is thinner and contains less fat between its leaves and is more translucent than the mesentery of the distal small bowel There is more of a marked tendency toward arborization and anastomosis of arterial and venous arcades in the mesentery of the distal ileum than in the mesentery of the proximal jejunum

ARTERIAL SUPPLY • Branches of SMA • Intestinal branches à gut (anastomose to form arcades) • Ileocolic artery à lowest part of ileum VENOUS DRAINAGE • correspond to branches of SMA • drain into superior mesenteric vein LYMPHATICS • Lymph vessels à intermediate nodes à superior mesenteric nodes INNERVATION • Sympathetic and vagus nerves from superior mesenteric plexus CLINICAL • Although trauma to the jejunum and ileum is common, the injury is less serious compared to trauma in the duodenum. This is because they are able to move freely, reducing crushing impact from blunt trauma. Penetrating injuries may selfseal through mucosal plugging. • Mesenteric arterial occlusion – the superior mesenteric artery supplies an extensive portion of the gut. An occlusion as the result of embolus, thrombus, aortic dissection, or abdominal aneurysm results in death of all or part of the gut from 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

Narrower, thinner, lighter (because of very small or absent plicae circularis), paler intestinal wall Mesentery attachment in posterior abdominal wall below and to the right of the aorta 3 or more arcades of mesenteric arteries

Abundant mesentery fat Laden and opaque Uniform deposition of fat, extending from root to wall Presence of Peyer’s No Peyer’s Patches 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 the proximal jejunum to the distal ileum

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