BIOL226Lec07_ the Pancreas

7/31/2019 BIOL226Lec07_ the Pancreas

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THE PANCREAS


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The Pancreas in situ

Right lobe of liver

Falciform ligament

Gallbladder

Pancreas

Duodenum

L-3


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Pancreas, Introduction, continued

D. Head fills concavity of duodenum

E. Body crosses left kidney

F. Tail reaches hilus of the spleen

G. Related anteriorly to transversecolon


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Pancreas in situ

Duodenum

Head of Pancreas


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Pancreas, Introduction, continued

H. Aorta, IVC lie posterior

I. Uncinate process:

a. Lies posterior to SMA and SMV

b. Lies anterior to aortaJ. Neck lies anterior to SMV, with

pylorus just above


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Venous Drainage of the PancreasIVC

SMV


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Introduction, continued

L. Body relatedposteriorly to left

crus, left adrenal,left renal vein, andsplenic vein

K. Celiac Axis(trunk, artery) liessuperior to body


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II. Detailed Anatomy

A. Landmark structures

1. Splenic Artery:

a. Branch of celiactrunk

b. passes right toleft

c. Course is alongupper margin ofbody and tail


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Detailed Anatomy, cont

2. Hepatic Artery:a. Branch of celiac trunk

b. courses left to rightc. along upper margin of neck and

head

3. Superior Mesenteric Artery: at itsorigin from aorta, points at body of

pancreas


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Arterial Supply to Pancreas

Common HepaticArtery

Proper HepaticArtery

SuperiorMesenteric Artery


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Landmark structures, continued

4. Splenic Vein:a. runs parallel

to arteryb. on posterior

surface ofpancreas

c. Terminates inportal vein


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5. Superior & InferiorMesenteric Veins:

a. pass (inferior tosuperior) deepto pancreas

b. merge with splenicvein

c. Terminate in portalvein


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6. Common Bile Duct:a. passes behind first portion of

duodenumb. then through head of pancreas

c. Terminates at ampulla of vater


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Detailed Anatomy continued

B. Head of Pancreas

1. Important clinically because:a. Numerous ducts and vessels traverse it

b. Carcinoma usually located here


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Head of Pancreas, Detailed Anatomy, continued

2. Tumor will compress surrounding

structuresa. First indication may be jaundiceb. Tumor may compress

duodenumc. May involve local vessels

*Metastases may spread through these vessels*


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3. Lymphatics from head of pancreas

a. Drain to celiac nodesb. metastases may follow lymph

c. Metastases may spread vialesser omentum to liver

d. Some terminate in lumbar nodes


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4. Vessels supplying head of pancreasa. Superior & inferiorpancreaticoduodenal arteries

b. Both divide into two parallelvessels

c. one anterior and one posterior tohead


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1. Anterior branch ofpancreaticoduodenal

arterya. superior branch:

anterior superiorpancreaticoduodenalartery

b. inferior branch:anterior inferior

pancreaticoduodenalartery


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2. Posterior branch ofpancreaticoduodenal

arterya. superior branch:

posterior superiorpancreaticoduodenal artery

b. inferior branch:posterior inferior

pancreaticoduodenal artery

**extensive blood supply**


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Anterior Pancreaticoduodenal Artery

Branches arecontinuous withone another

Superiorbranchesoriginate from theGDA

Inferior branchesoriginate from theSMA


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Detailed Anatomy, continued

C. Body & Tail of Pancreas:

1. Supplied by splenic artery2. Have three surfaces:

a. Anterior surface

1. Concave2. Deep to stomach3. Separated from stomach by

lesser sac of peritoneum

(aka omental bursa)


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Anterior surface of pancreas

Anterior surfaceof pancreas

Epiploicforamen


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Lesser sac, continued

4. Lesser sac bounded by:

a. Liver, superiorlyb. Below, extends to

greater omentumc. Anteriorly: lesser

omentum, stomach,greater omentum


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Lesser sac, continued

d. Posteriorly: greateromentum

transverse colon,transverse mesocolon

e. Laterally:

1. Foramen of Winslow onright

2. Spleen on left


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f. Foramen of Winslow (AKA: Epiploic

Foramen):

1. Lies between greater & lesser

sacs of peritoneum

2. posterior to free edge oflesser omentum

3. close to porta hepatis


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Three Surfaces, continued

2. Posterior surface: separated from vertebrae by

a. Aorta

b. Splenic veinc. Left kidney and renal vesselsd. Left adrenal glande. Left Crus of diaphragmf. SMA and SMV


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D. Pancreatic Duct System

1. Pancreatic Duct (of Wirsung)a. Course is left to rightb. Receives numerous small ducts

c. @ neck of pancreas, duct turnsinferior, posterior & to the rightd. AKAmain pancreatic duct


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Duct of Wirsung (Main pancreatic duct)


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Pancreatic Duct System, continued

d. joins CBD at Ampulla of Vater

3 - 4 below pyloruse. results from fusion of ducts during

fetal development

1. One from ventral pancreas2. One from dorsal pancreas

(see Netters Embryology, p. 142, for Pancreasdevelopment)


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Duct of Wirsung

Duct ofWirsung


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Pancreatic Duct System, continued

2. Duct of Santorini:a. accessory pancreatic duct

b. Not universally identified

c. joins duodenum @ minor papilla

d. part of duct from dorsal pancreas


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Duct of Santorini


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III. Scanning AnatomyA. Depends on recognition of pancreatic

margins

B. Sonography best used as screeningprocedure

1. May be interference from bowelgas (especially in tail region)


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Scanning Anatomy, continued

2. Extremely accurate in detectionof pseudocysts

3. U/S can show texture of organ

4. By ID-ing vessels, can delineate

head, portions of body


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C. Head:1. SMV outlines medial head to neck

region2. Duodenum & GB outline lateral

head

3. Superiorly, delineated bygastroduodenal artery (GDA)

4. Inferiorly, bounded by CBD


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D. Further delineation by vascularlandmarks:

1. SMA:

a. Lies immediately posterior to

body, points to it!b. Recognized by echogenic fat

collar surrounding vessel


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Vascular Landmarks of the Pancreas

Pancreaticsonography

depends largelyon identifyingsurroundinglandmark vessels


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2. SMV:a. Delineates medial headb. Larger diameter than SMAc. Lies to right of SMAd. Uncinate process wraps it (and

SMA), lies posterior & medial


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Vascular Landmarks of the Pancreas

Venouslandmarks of the

pancreasinclude the SMVand renal veins


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E. Tail of Pancreas

1. May be visualized through fluid-filledstomach

2. Tail seen as 2-3 cm roundedmass anterior to hilus of left kidney


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Pancreatitis, Pancreatic Disorders, continued

5. Important factor is release of proteinkinins

a. Increase permeability of vessels& cells

b. Releases tissue fluidc. Edema may compress vesselsd. Tissue damage occurs


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Pancreatic Disorders, continued

B. Pseudocysts:

1. False cysts that may arisea. due to tissue necrosis

b. From enzymatic destruction

2. May persist after inflammation subsides

3. Usually near or in pancreas


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Pancreatic Diseases, continued

D. Chronic Pancreatitis

1. organ usually appears as small,atrophic

2. Contains scattered echoes fromcalcifications

3. Primary cause is alcoholism


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E. Dilation of Pancreatic Duct

1. Seen in acute or chronicpancreatitis

2. Frequently associated withneoplasm of pancreas

3. Biliary tract problems


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F. Abscess or Hemorrhagic Pancreatitis

1. Similar in sonographic appearance2. Hemorrhagic:a. Mass with inhomogeneous texture

b. Acute hemorrhage: sonolucent to

echogenicc. CT scan used for differentiation


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G. Pancreatic Tumors

1. Malignant tumors usually ariseas adenocarcinomas

2. In head of Pancreas: Sx

a. Painless jaundiceb. Anorexia


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Pancreatic Tumors, In head, continued

c. Nausea

d. Weight losse. Increased plasma amylase

f. Increased alkaline phosphatase

g. May involve compression ofpancreatic duct, CBD


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Pancreatic Tumors in the Head

Tumors in the headmay compressbiliary ducts orpancreatic ducts


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Pancreatic tumors, continued

3. In Body of Pancreas: Sxa. Gnawing pain radiating to back

b. Pain increases after eating orlying down

c. Weight loss, anorexia

d. Large tumor may compress IVC,portal vein


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4. In Tail ofPancreas: Sx

a. Often silent until localmetastasis occurs

b. May metastasize to:1. para-aortic lymph

nodes2. spleen


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5. Identified by organ enlargement,

subtle echo changes, irregular outline

6. Metastases to stomach, liver & lungsare common

7. Often causes dilation of ducts


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H. Fibrocystic Disease1. Result of cystic fibrosis

2. Diagnosed by methods other than

ultrasound


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I. Pancreaticolithiasis

1. Characteristic stone echoes in pancreatic duct

2. May see atrophied pancreatic parenchyma

3. Associated with chronic alcoholic pancreatitis

4. Contours of body, tail show irregularities


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Pancreatolithiasis, continued

5. Incidence slightly higher in head

6. Associated with occult pancreaticcarcinoma

a. Mass < 2mm diameter

b. Seen with dilation of pancreaticduct or CBD

BIOL226Lec07_ the Pancreas

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