E2D

Question 1

duodenum

Answer 1

C-shaped tube, about 10 inches long, that curves around head of pancreas; located in epigastric and umbilical regions; begins at pyloric orifice and ends at duodenojejunal flexure

its initial segment is intraperitoneal (like stomach): remaining of duodenum is secondary retroperitoneal (only its anterior surface is covered by peritoneum)

Question 2

duodenum parts

Answer 2

1st (superior), 2nd (descending), 3rd (inferior, horizontal or transverse) and 4th (ascending)

Question 3

duodenum relations

Answer 3

gastroduodenal artery passes posterior to 1st part of duodenum: a peptic ulcer in posterior wall of 1st part of duodenum can erode gastroduodenal artery or one of its branches causing a massive hemorrhage

gallbladder is anterior to 1st part and upper portion of 2nd part of duodenum  inflammation of gallbladder can create adhesions or even a fistula between gallbladder and duodenum

superior mesenteric artery and vein pass anterior to 3rd part of duodenum; an aneurysm of SMA can compress 3rd part of duodenum causing intestinal obstruction

Question 4

duodenum internal structure

Answer 4

in approximately the first 2cm, duodenal mucosa is smooth (duodenal ampulla/cap)
remaining of duodenum: mucosal surface has numerous folds  circular folds (plicae circulares)

Question 5

major duodenal papilla

Answer 5

small elevation located approximately half-way down posteromedial wall of 2nd part of duodenum, created by hepatopancreatic ampulla (of Vater); has small orifice at its tip (opening of hepatopancreatic ampulla) that releases bile and pancreatic enzymes into duodenum

Question 6

minor duodenal papilla (inconstant)

Answer 6

located in 2nd part of duodenum, about 2cm above major duodenal papilla; marks opening of accessory pancreatic duct

Question 7

jejunum and ileum

Answer 7

jejunum begins at duodenojejunal flexure and ileum ends at ileocecal junction; each has peculiar features, but there is a gradual change from one to the other (no sharp boundary between them)

coils of jejunum and ileum are intraperitoneal and freely movable; attached to posterior abdominal wall by mesentery of small intestine, which allows branches of superior mesenteric vessels, lymph vessels and nerves to reach jejunum and ileum

root of mesentery of small intestine extends inferiorly and to the right from left side of L2 to right sacroiliac joint

Question 8

jejunum/ileum differences

Answer 8

coils of jejunum lie in upper part of infracolic compartment; coils of ileum are in lower part of infracolic compartment and pelvic cavity

jejunum has larger diameter and thicker walls than ileum

in jejunum circular folds are larger and more numerous than in ileum

jejunal arteries form less number of arcades than ileal arteries; straight arteries (vasa recta), which originate from last series of arcades, are longer in jejunum than ileum

aggregated lymphoid follicles/nodules (Peyer’s patches) are present in ileum along its antimesenteric border (not present in jejunum)

ileum has more mesenteric fat than jejunum

Question 9

large intestine

Answer 9

extends from ileocecal junction to anus

mainly concerned with absorption of water and electrolytes and storage of undigested materials until they can be eliminated from body as feces

parts: cecum with vermiform appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal

Question 10

ileal (ileocecal) orifice

Answer 10

located in medial wall of cecum; guarded by 2 mucosal folds (superior and inferior ileocecal lips, formerly known as ileocecal valve); play little or no role in preventing reflux from cecum to ileum (major role is played by circular muscle at end of ileum)

Question 11

small vs large intestine

Answer 11

teniae coli: 3 bands of longitudinally arranged smooth muscles fibers, approximately equally spaced around circumference of large intestine  named according to their relations to peritoneal attachments of transverse colon (omental tenia, mesocolic tenia and free tenia)

large intestine has fatty appendices (epiploic/omental appendices): not present in small intestine

wall of small intestine is smooth: wall of large intestine is sacculated (haustra)

Question 12

vermiform appendix

Answer 12

narrow muscular tube containing large amount of lymphoid tissue

intraperitoneal: has small mesentery (mesoappendix) that contains appendicular vessels

McBurney’s point: located at junction of lateral and middle thirds of a line joining right ASIS to umbilicus; area of greatest tenderness in appendicitis

3 teniae coli converge at base of appendix (useful in locating appendix during surgery)

position of appendix is variable; retrocecal (most common), hanging down into pelvis against right pelvic wall, below cecum, projecting upward anterior or posterior to terminal part of ileum

sensory fibers carrying pain from appendix terminate in spinal cord at level of T10; pain referred around umbilicus

Question 13

pancreas

Answer 13

exocrine part produces enzymes involved in digestion of proteins, fats and carbohydrates

endocrine part (pancreatic islets [of Langerhans]) produces hormones (main ones are insulin and glucagon)

elongated organ that lies in epigastric and left hypochondriac regions; deeply located on posterior abdominal wall, behind peritoneal sac (most of it is secondary retroperitoneal)

Question 14

pancreas head

Answer 14

lies within concavity of duodenum

uncinate process: tongue-like process of lower part of head that extends to the left, posterior to superior mesenteric vessels

Question 15

pancreas neck

Answer 15

slightly constricted part between head and body

located anterior to origins of portal vein and superior mesenteric artery

Question 16

pancreas body

Answer 16

longest part, extends to the leg and slightly superiorly

Question 17

pancreas tail

Answer 17

located within splenorenal ligament; comes in contact with hilum of spleen (only part of pancreas that is intraperitoneal)

Question 18

pancreas anatomical relations

Answer 18

anteriorly: lesser sac, stomach, root of transverse mesocolon
posteriorly: common bile duct, origin of portal vein, IVC, abdominal aorta with origin of superior mesenteric artery, splenic vein, left kidney, left suprarenal gland
superiorly: splenic artery

Question 19

pancreas ducts

Answer 19

principal (main) pancreatic duct: begins in tail and runs length of organ  opens into 2nd part of duodenum (together with common bile duct) on major duodenal papilla

accessory pancreatic duct: drains upper part of head  opens into 2nd part of duodenum on minor duodenal papilla

two ducts usually communicate with each other

Question 20

superior mesenteric artery (SMA)

Answer 20

unpaired visceral branch of abdominal aorta; originates from anterior aspect of abdominal aorta at level of L1, posterior to neck of pancreas

runs inferiorly and to the right  at its origin it passes anterior to left renal vein, then it passes anterior to uncinate process of pancreas and 3rd part of duodenum and continues along root of mesentery of small intestine (aneurysms of initial part of SMA can compress left renal vein or 3rd part of duodenum)

supplies lower part of head of pancreas, distal part of duodenum, jejunum, ileum, cecum, appendix, ascending colon and proximal ⅔ of transverse colon

Question 21

SMA branches

Answer 21

inferior pancreaticoduodenal artery
jejunal and ileal (intestinal) arteries
ileocolic artery
right colic artery 
middle colic

Question 22

inferior pancreaticoduodenal artery

Answer 22

divides into anterior and posterior branches, which pass to the right supplying lower part of head of pancreas and distal half of duodenum; anastomose with superior pancreaticoduodenal branches of gastroduodenal artery (anastomosis between CT and SMA)

Question 23

jejunal and ileal (intestinal) arteries

Answer 23

12 to 15 in number; originate from left side of SMA, run between 2 layers of mesentery of small intestine to reach coils of jejunum and ileum, form arterial arcades that increase in number from jejunum to ileum; terminal arcades give rise to straight arteries that supply intestinal wall

Question 24

ileocolic artery

Answer 24

lowermost of branches that originate from right side of SMA, runs inferiorly and to the right, toward ileocecal junction, behind peritoneum
its branches supply terminal ileum, cecum, appendix and beginning of ascending colon

Question 25

right colic artery

Answer 25

runs to the right, behind peritoneum, to supply ascending colon and beginning of transverse colon; exhibits considerable variability (may originate from SMA, ileocolic artery, middle colic artery or it may be absent)

Question 26

middle colic

Answer 26

runs between 2 layers of transverse mesocolon; its branches supply proximal ⅔ of transverse colon; anastomoses with left colic artery (branch of IMA)

Question 27

inferior mesenteric artery (IMA)

Answer 27

lowest unpaired visceral branch of abdominal aorta; originates from anterior aspect of abdominal aorta at level of L3

runs inferiorly, posterior to peritoneum, in left infracolic space, crosses left common iliac vessels and continues into pelvis as superior rectal artery

supplies distal ⅓ of transverse colon, descending colon, sigmoid colon, rectum and upper half of anal canal

Question 28

inferior mesenteric artery branches

Answer 28

left colic artery:
sigmoid arteries
superior rectal artery

Question 29

left colic artery

Answer 29

runs to the left, behind peritoneum, its branches supply distal ⅓ of transverse colon and descending colon, anastomoses with middle colic artery (branch of SMA)

Question 30

sigmoid arteries

Answer 30

2 or 3 in number; run between 2 layers of sigmoid mesocolon  supply sigmoid colon

Question 31

superior rectal artery

Answer 31

inferior continuation of IMA; descends into pelvis posterior to rectum; supplies rectum and upper half of anal canal

anastomoses with middle and inferior rectal arteries (branches of internal iliac and internal pudendal arteries, respectively)

Question 32

marginal artery

Answer 32

continuous arterial channel that skirts inner margin of colon from ileocecal junction to rectosigmoid junction

formed by anastomoses between branches of ileocolic, right colic, middle colic, left colic and sigmoid arteries

can serve as a source of collateral circulation to a part of colon after its chief arterial supply has been obstructed or ligated

Question 33

portal vein

Answer 33

drains blood from most of alimentary canal (from lower ⅓ of esophagus to upper ½ of anal canal), spleen and pancreas; terminates in liver

begins posterior to neck of pancreas by union of superior mesenteric and splenic veins

runs superiorly and to the right, passes posterior to 1st part of duodenum, runs within hepatoduodenal ligament (posterior to proper hepatic artery and common bile duct); divides into right and left terminal branches at porta hepatis

Question 34

portal vein tributaries

Answer 34

splenic vein 
inferior mesenteric vein
superior mesenteric vein
R/L gastric veins
superior panrceaticoduodenal veins
cystic veins
paraumbilical veins

Question 35

splenic vein

Answer 35

begins at hilum of spleen, runs to the right, posterior to pancreas, and inferior to splenic artery
joins superior mesenteric vein posterior to neck of pancreas to form portal vein; receives tributaries that correspond with branches of splenic artery (short gastric, left gastroepiploic, pancreatic veins) as well as inferior mesenteric vein

Question 36

inferior mesenteric vein

Answer 36

drains territory supplied by inferior mesenteric artery (receives left colic, sigmoid and superior rectal veins); ascends on posterior abdominal wall, posterior to peritoneum; usually terminates by joining splenic vein posterior to pancreas, but may end at junction of splenic and superior mesenteric veins or drain into superior mesenteric vein

Question 37

superior mesenteric vein

Answer 37

ascends in root of mesentery of small intestine on right side of SMA; passes anterior to 3rd part of duodenum and uncinate process of pancreas; joins splenic vein posterior to neck of pancreas to form portal vein; receives tributaries that correspond with branches of SMA (inferior pancreaticoduodenal, jejunal, ileal, ileocolic, right colic and middle colic veins) and right gastroepiploic vein

Question 38

right and left gastric veins

Answer 38

collect blood from lesser curvature of stomach; drain directly into portal vein

Question 39

superior pancreaticoduodenal veins

Answer 39

drain into portal vein or superior mesenteric vein

Question 40

cystic veins

Answer 40

drain gallbladder directly into liver or join portal vein

Question 41

paraumbilical veins

Answer 41

very small veins that run along round ligament of liver; connect veins of anterior abdominal wall with portal vein (usually its left branch)

Question 42

portal-systemic anastomoses

P-SA

Answer 42

in normal conditions, portal venous blood passes through liver and drains into IVC, which then carries it to heart (direct route)

other routes of communication exist between portal and systemic (SVC, IVC) circulations; become important if direct route is blocked causing portal hypertension (ex.: cirrhosis of liver); in patients with portal hypertension, portal-systemic anastomoses become enlarged (varicose veins), can rupture and bleed

wherever non-peritoneal areas of intestines, liver and pancreas (portal circulation) are in contact with body wall (systemic circulation)

Question 43

esophagus P-SA

Answer 43

in lower part of esophagus, esophageal veins that drain into left gastric vein (portal circulation) anastomose with esophageal veins that drain into azygos venous system (systemic circulation, SVC); enlargement of these veins in portal hypertension causes esophageal varices

Question 44

rectum P-SA

Answer 44

in walls of rectum and anal canal; tributaries of superior rectal vein (portal circulation) anastomose with tributaries of middle and inferior rectal veins (systemic circulation, IVC); enlargement of these veins in portal hypertension causes internal hemorrhoids (most hemorrhoids are NOT associated with portal hypertension)

Question 45

abdominal wall P-SA

Answer 45

in anterior abdominal wall; paraumbilical veins (portal circulation) anastomose with superficial veins of anterior abdominal wall which drain superiorly into axillary vein or inferiorly into femoral vein (systemic circulation); enlargement of these veins in portal hypertension causes caput Medusae