GI System

Question 1

describe the 2 layers of the peritoneum

Answer 1

• parietal peritoneum: lines the internal surface of abdominal wall
• visceral peritoneum: clothes the abdominal organs

Question 2

contrast the innervation of parietal peritoneum vs visceral peritoneum

Answer 2

• parietal peritoneum: somatopleure
  
  • innervated by somatic afferents from the spinal nerves associated with the region of the abdominal wall where it is located; usually well localized
• visceral peritoneum; splanchnopleure
  
  • innervated by visceral afferents which accompany autonomic nerves supplying the organ; pain poorly localized

Question 3

describe ascites

Answer 3

• abnormal fluid within peritoneal cavity between visceral and parietal layers

Question 4

name the intraperitoneal organs (have a mesentery)

Answer 4

• stomach
• liver
• duodenum 1st part
• small intestine (jejunum, ileum)
• spleen
• cecum and appendix
• transverse and sigmoid colon

Question 5

describe primary retroperitoneal organs (posterior body wall behind peritoneum)

Answer 5

• kidneys
• ureters
• aorta
• IVC
• sympathetic trunks

Question 6

name secondary retroperitoneal organs

Answer 6

• pancreas
• duodenum 2nd, 3rd and 4th part
• ascending colon
• descending colon
• rectum

Question 7

which ligaments are formed from the ventral mesentery?

Answer 7

• hepatogastric ligament
• falciform ligament

Question 8

name the ligaments of the greater omentum

Answer 8

• gastrophernic ligament
• gastrosplenic ligament
• gastrocolic ligament: to the transverse colon and mesoclon

Question 9

name the 2 ligaments of the lesser omentum

Answer 9

• hepatogatric ligament contains gastric arteries
• hepatoduodenal ligament contains portal triad

Question 10

explain compression of hepatoduodenal ligament (aka Pringle maneuver)

Answer 10

• clamping of this ligament prevents inflow of blood into the liver thereby reducing bleeding in the liver as a result of traumatic injury

Question 11

perforation of a peptic ulcer of the stomach along its posterior wall will result in ______

Answer 11

perforation of a peptic ulcer of the stomach along its posterior wall will result in blood collecting in the lesser sac which could then communicate with the greater sac through the omental foramen

Question 12

contrast the left paracolic gutter with the right paracolic gutter

Answer 12

• the left paracolic gutter is narrower and partially obstructed by the phrenicolic ligament, therefore it is easier for infections to travel to the right subphrenic space

Question 13

name the boundaries of the omental foramen (which is the communication between the lesser and greater sac)

Answer 13

• anterior: hepatoduodenal ligament w/ the portal triad
• inferior: duodenum (sup. part)
• posterior: IVC
• superior: caudate lobe of liver

Question 14

describe the hepatorenal recess aka Pouch of Morrison

Answer 14

the lowest point in the peritoneal cavity where pathological fluid can collect and can be aspirated to test

Question 15

name the spaces where fluid can collect in females

Answer 15

Question 16

name the space where fluid can collect in males

Answer 16

Question 17

name the 4 sites of esophageal constriction

Answer 17

1. junction of esophagus with pharnyx
2. where esophagus is crossed by arch of aorta
3. esophagus compressed by left main bronchus
4. where it enters the stomach at lower esophageal sphincter

Question 18

name the branches of the celiac trunk

Answer 18

• left gastric (anastomoses with right gastric at lesser curvature)
• splenic (largest a.)
  
  • left gastro-omental (anastomose with RGO to supply greater curv)
  • short gastric (supplies fundus)
• common hepatic a.
  
  • proper hepatic
    
    • gastroduodenal
      
      • right gastro-omental (anastomose with LGO to supply greater curv)
  • right gastric (anastomoses w/ left gastric at lesser curv)

Question 19

describe perforated ulcers

Answer 19

• sudden and severe pain in the abdomen
• board-like rigidity of the abdomen
• abnormal finding of “free air” under the diaphragm
• if ulcer has perforated into a surrounding vessel then excessive bleeding may cause hemodynamic compromise

Question 20

describe peptic ulcers

Answer 20

• ulcers occur most commonly in the first part of the duodenum, called the duodenal bulb
• flow of acid through the pyloric valve is directed toward the posterior wall of the bulb
• deep ulceration can invade the gastroduodenal artery or its branches (posterior superior pancreaticoduodenal artery)
• anterior duodenal ulcers = peritoneal cavity = peritonitis

Question 21

describe stomach perforations and where contents can leak

Answer 21

• posterior perforation:
  
  • contents into lesser sac (omental bursa) can lead to spilling of gastric contents inducing peritonitis –> pancreatitis
    
    • if turns to the left, lesser sac
    • if turns to the right, from lesser sac to hepatorenal recess
• anterior perforation: contents into the greater sac

Question 22

name the arteries

Answer 22

1. proper hepatic
2. common hepatic
3. gastroduodenal (1st branch off common hepatic)
4. splenic

Question 23

describe the 1st part of the duodenum

Answer 23

superior: located at L1 vertebra, proximal part called the duodenal bulb, is suspended by a mesentery

Question 24

describe the 2nd part of the duodenum

Answer 24

• descending: located along the right side of L1-L3 vertebra
  
  • contains the hepatopancreatic duct
  • major and minor duodenal papilla and the accessory pancreatic duct

Question 25

describe the 3rd part of the duodenum

Answer 25

* horizontal: against aorta and vena cava, superior mesenteric vessels run anterior to it

Question 26

describe the 4th part of the duodenum

Answer 26

* ascending: ascends along the left side of the aorta to the level of L2 at the inf. border of the pancreas * **anchored to diaphragm by ligament of Treitz**

Question 27

describe the blood supply/venous draining/lymph drainage of the small intestine

Answer 27

* **superior mesenteric artery** supplies the small intestine * veins correspond to the arteries and these veins drain into the **superior mesenteric vein** * lymphatic channels from small intestine drain into **superior mesenteric nodes**

Question 28

describe the innervation of the appendix

Answer 28

* the appendix is innvervated by T10, as is the periumbilical region * the referred pain to this area initially carried by visceral afferent fibers from appendix to DRG * when appendix becomes inflammed, it makes contact with the body wall (right iliac fossa)

Question 29

describe a psoas test

Answer 29

* **used to diagnose appendicitis** * when the patient actively flexes their thigh at the hip, an inflammed appendix can make contact with the body wall

Question 30

contrast small bowel vs large bowel obstruction

Answer 30

* small bowel = centrally located * "stacks of coins" appearance; plica semilunaris * large bowel = peripherally located * presence of haustra

Question 31

describe importance of pectinate line

Answer 31

* above pectinate line = endodermal origin = visceral afferents * below pectinate line = ectodermal origin = somatic afferents

Question 32

contrast internal vs external hemorrhoids

Answer 32

* internal hemorrhoidal veins = **painless since it travels with visceral afferents** * external hemorrhoidal veins = **painful since it travels with somatic afferents**

Question 33

describe the venous drainage of the rectum

Answer 33

* the internal rectal plexus drains in both directions at the level of the pectinate line * _superior to pectinate line_ the int. venous plexus drains into the sup. rectal vein * _inferior to pectinate line_, the int. venous plexus drains into the inf. rectal veins

Question 34

describe the portal and caval rectal anastomosis and lymph drainage

Answer 34

* lymphatics: * above pect. line = internal ilac nodes * below pect. line = superficial horizontal inguinal nodes * portal hypertension: * the portocaval anastomosis among the superior middle and inf. retal veins become varicosed

Question 35

describe divertuculosis

Answer 35

* outpouching of colonic mucosa and submucosa that herniate through muscular layer * generally found in the sigmoid colon * may erode into colonic vessels causing bleeding * can lead to **diverticulitis** * obstruction of the diverticulum leading to infxn; if rupture occurs, it may lead to peritonitis/fistula formation

Question 36

describe sigmoid volvulus

Answer 36

* sigmoid volvulus is a twisting of the sigmoid colon around its mesentery causing obstruction of the colon * "coffee bean" appearance

Question 37

name arteries of the large intestine

Answer 37

the marginal artery (of Drummond) is an artery that **anastomoses the inferior mesenteric artery with the superior mesenteric artery**