Gastro - Anatomy Flashcards
What two blood vessels and one nerve run anterior to the spine at the level of the umbilicus?
The aorta, inferior vena cava, and sympathetic trunk run together along the spine.
What branch of the abdominal aorta supplies the foregut?
Coeliac trunk
What is the most superficial muscle group making up the lateral abdominal wall?
External oblique
What is the deepest muscle group making up the lateral abdominal wall?
Transversus abdominis
What is the name of the connective tissue that lies between the rectus muscles at the midline?
Linea alba
What individual layers of fascia join to make the rectus sheath?
Fascia of the external oblique, internal oblique, and transversus abdominus
Which parts of the duodenum are retroperitoneal?
The second, third, and fourth parts of the duodenum
Name two major organs that lie completely in the retroperitoneal space.
The kidneys and adrenal glands
What part of the pancreas is not found in the retroperitoneal space?
The tail of the pancreas
Which two parts of the urinary system are retroperitoneal?
The kidney and ureters
Which portion of the colon is not retroperitoneal?
Transverse colon
In the gastrointestinal tract, the falciform ligament connects which two structures?
The liver and the abdominal wall
In the gastrointestinal tract, the gastrohepatic ligament connects which two structures?
The liver and the lesser curvature of the stomach
In the gastrointestinal tract, the gastrocolic ligament connects which two structures?
The transverse colon and the greater curvature of the stomach
In the gastrointestinal tract, the gastrosplenic ligament connects which two structures?
The spleen and the greater curvature of the stomach
In the gastrointestinal tract, the splenorenal ligament connects which two structures?
The spleen and the posterior abdominal wall
The _____ ligament connects the liver and the duodenum.
Hepatoduodenal
The falciform ligament contains what structure?
The ligamentum teres
The hepatoduodenal ligament contains what structures?
The portal triad (the portal vein, the portal artery, and the common bile duct)
The gastrohepatic ligament contains what structures?
The gastric arteries
The gastrocolic ligament contains what structures?
The gastroepiploic arteries
The splenorenal ligament contains what structures?
The splenic artery and the splenic vein
From what fetal structure is the falciform ligament derived?
Fetal umbilical vein
The portal triad can be compressed through what opening to control bleeding?
The omental foramen (also known as the epiploic foramen of Winslow)
What gastrointestinal ligament can be cut to access the lesser sac during surgery?
The gastrohepatic ligament
What ligament is part of the greater omentum?
Gastrocolic ligament
What ligament separates the greater and lesser sacs?
Gastrosplenic ligament
Which layer of the muscularis externa is closer to the lumen: the circular layer or the longitudinal layer?
The circular layer
List three components of the gut wall mucosa.
Epithelium, lamina propria, and muscularis mucosa
What is the primary function of the epithelium of the gut wall mucosa?
Absorption
What is the primary function of the lamina propria of the gut wall mucosa?
Support
What is the primary function of the muscularis mucosa of the gut wall mucosa?
Mucosal motility
What structure is found within the submucosa of the gut wall?
The submucosal nerve plexus (Meissner’s plexus)
Meissner’s plexus controls what three functions of the submucosal gut wall?
Secretions, blood flow, and absorption
What lies between the inner circular and outer longitudinal layers of the muscularis externa?
The myenteric nerve plexus (Auerbach’s plexus)
List the four main layers of the gut wall, starting from the inside and going out.
Mucosa, submucosa, muscularis externa, and serosa
What is the rate of basal electrical rhythm in the stomach?
3 waves/min
What is the rate of basal electrical rhythm in the duodenum?
12 waves/min
What is the rate of basal electrical rhythm in the ileum?
8-9 waves/min
Villi are found in which section of the digestive tract?
Small intestine
Describe the epithelium of the esophagus in histological terms.
Nonkeratinized stratified squamous cell epithelium
A patient presents with intractable diarrhea and is found to have celiac disease. What microstructure is damaged and where is it located?
The villi and the microvilli of the small intestine are likely damaged resulting in decreased absorptive capacity and diarrhoea
What part of the small intestine has the highest concentration of villi and microvilli?
Duodenum; villi increase the surface area of the epithelium to maximize absorption
Name a submucosal structure that is unique to the duodenum.
Brunner’s glands
These epithelial glands are found throughout the small intestine.
Crypts of Lieberkühn
Goblet cells are highly concentrated in this area of the small intestine.
Jejunum
Which immunologic structures are unique to the Ileum?
Peyer’s patches
Name a major histological difference between the duodenum and the colon.
The duodenum has villi whereas the colon only has crypts
The primary function of the myenteric plexus is to coordinate what function?
Motility along the entire gut wall
The myenteric plexus is located between what two smooth muscle layers?
The inner circular layer and the outer longitudinal layer (remember: AUerbach’s is on the Autside)
The submucosal plexus is located between what two layers?
The mucosa and the inner layer of smooth muscle
What are the functions of the submucosal nerve plexus?
Regulation of secretions, blood flow, and absorption
The upper one-third of the esophagus is composed of _____ muscle.
Striated
The lower one-third of the esophagus is composed of ______ muscle.
Smooth
What type of muscle fibers make up the middle one third of the esophagus?
Both striated and smooth muscle
This branch of the aorta supplies the foregut.
Coeliac trunk
Which branch of the aorta comes off at the level of L1?
The superior mesenteric artery
Which paired arteries come off the aorta at the level of L2?
The ovarian or testicular arteries
Which paired arteries come off the aorta at the level of L1?
The renal arteries
At what level does the abdominal aorta bifurcate?
L4
Which two arteries does the aorta become after the bifurcation?
Left and right common iliac arteries
An elderly patient presents with bright red bleeding per rectum and is found to be hypotensive. On colonoscopy, she is found to have necrotic mucosa at the splenic flexure. What is the blood supply to this region?
Inferior and superior mesenteric arteries
What are the three embryologic divisions of the gastrointestinal tract?
The foregut, midgut, and hindgut
Which artery supplies the foregut?
Coeliac trunk
Which artery supplies the midgut?
The superior mesenteric artery
Which artery supplies the hindgut?
Inferior mesenteric artery
What are the main gastrointestinal structures derived from the embryonic foregut?
The stomach, proximal duodenum, liver, gallbladder, and pancreas
What portion of the gastrointestinal tract is derived from the embryonic midgut?
From the distal duodenum to the proximal two-thirds of the transverse colon
What portion of the gastrointestinal tract is derived from the embryonic hindgut?
From the distal one-third of the transverse colon to the upper rectum
What organ supplied by the celiac trunk is not an embryonic gut derivative?
Spleen
Which segments of the gastrointestinal tract receive parasympathetic innervation from the vagus?
Foregut (stomach to proximal duodenum, liver, gallbladder, pancreas, spleen) and midgut (distal duodenum to proximal 2/3 of transverse colon)
The stomach receives its main blood supply from branches of what structure?
The coeliac trunk
Name the three main branches of the celiac trunk.
Common hepatic artery, splenic artery, and left gastric artery
From what artery does the cystic artery arise?
The right hepatic artery, a branch of the common hepatic artery; the cystic artery supplies the gallbladder
What are the main branches of the common hepatic artery?
The right gastric artery, gastroduodenal artery, and hepatic artery proper
What are the two branches of the gastroduodenal artery?
Superior pancreaticoduodenal and right gastroepiploic arteries
What arteries feed the greater curvature of the stomach?
The right and left gastroepiploic arteries
What arteries feed the lesser curvature of the stomach?
The right and left gastric arteries
The short gastric arteries have poor anastomoses if the _____ artery is blocked.
Splenic
Strong anastomoses exist between what two sets of arteries of the celiac trunk?
Left and right gastroepiploics and left and right gastrics
What are the branches of the splenic artery?
The short gastrics and left gastroepiploic artery
If the abdominal aorta is blocked, blood can travel through the subclavian artery into the internal thoracic artery and then through an anastomosis to which artery?
Superior epigastric (internal thoracic)
If the abdominal aorta is blocked, the superior pancreaticoduodenal artery of the celiac trunk can anastamose with what vessel?
Inferior pancreaticoduodenal artery (of the superior mesenteric artery)
If the abdominal aorta is blocked, which artery can anastamose with the left colic artery (of the inferior mesenteric artery)?
Middle colic artery (of the superior mesenteric artery)
The superior rectal artery (of the inferior mesenteric artery) can anastamose with what artery?
Middle rectal artery (of the internal iliac)
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: _____ _____ (from the subclavian) to the superior epigastric (internal thoracic) to the inferior epigastric (normally fed by the external iliac).
Internal mammary
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: internal mammary (from the subclavian) to the _____ _____ (internal thoracic) to the inferior epigastric (normally fed by the external iliac).
Superior epigastric
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: internal mammary (from the subclavian) to the superior epigastric (internal thoracic) to the _____ _____ (normally fed by the external iliac).
Inferior epigastric
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: _____ _____ (from the celiac trunk) to the inferior pancreaticoduodenal (normally fed by the superior mesenteric artery).
Superior pancreaticoduodenal
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: superior pancreaticoduodenal (from the celiac trunk) to the _____ _____ (normally fed by the superior mesenteric artery).
Inferior pancreaticoduodenal
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: _____ _____ (from the inferior mesenteric artery) to the middle rectal (normally fed by the internal iliac).
Superior rectal
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: superior rectal (from the inferior mesenteric artery) to the _____ _____ (normally fed by the internal iliac).
Middle rectal
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: _____ _____ (from the superior mesenteric artery) to the left colic (normally fed by the inferior mesenteric artery).
Middle colic
If the abdominal aorta is blocked, there are several anastomoses that will provide collateral flow. Complete this one: middle colic (from the superior mesenteric artery) to the _____ _____ (normally fed by the inferior mesenteric artery).
Left colic
Give three examples of clinical manifestations of portosystemic anastomoses seen in patients with portal hypertension.
Esophageal varices, internal hemorrhoids, and caput medusae
remember: gut, butt, and caput
A chronic alcoholic patient presents with mental status change, tense ascites, and hematemesis. What is a likely cause of his hematemesis?
Portal hypertension from his cirrhosis (as evidenced by his ascites) created esophageal varices that ruptured, causing hematemesis
A patient with portal hypertension presents with discomfort on defecation and bright red blood per rectum. Physical examination shows prolapsed dilated veins around the anus that are not tender. What is the explanation of these findings?
A portosystemic anastomoses between the superior and middle rectal arteries created internal hemorrhoids, which are painless
Portal-systemic anastomoses from the paraumbilical vein to the inferior epigastric and superior epigastric veins can manifest as what?
Caput medusae at the navel
What condition causes portal-systemic anastomoses?
Portal hypertension
What is the underlying principle in surgical treatment of portal hypertension?
Creation of anastomoses to shunt blood from portal circulation into systemic circulation, thereby bypassing the liver
Name two potential shunts that can be created surgically to relieve portal hypertension.
Splenic vein to left renal vein; portal vein to inferior vena cava
The pectinate line is formed where the embryonic _____ derivatives meet the _____ derivatives.
Hindgut; ectodermal
What type of hemorrhoids occur above the pectinate line? Below the pectinate line?
Internal; external
True or False? Internal hemorrhoids are painful.
False; internal hemorrhoids are not painful whereas external hemorrhoids are painful
What type of cancer occurs above the pectinate line in the rectum? Below the pectinate line?
Adenocarcinoma; squamous cell carcinoma
Above the pectinate line, there is what type of innervation: visceral or somatic?
Visceral innervation
Above the pectinate line, the arterial supply comes from what artery?
The superior rectal artery
The superior rectal artery is a branch of what artery?
The inferior mesenteric artery
Below the pectinate line, there is what type of innervation, somatic or visceral?
Somatic innervation
Below the pectinate line, the arterial supply is from what artery?
The inferior rectal artery
The inferior rectal artery is a branch of what artery?
The internal pudendal artery
_____ hemorrhoids receive somatic innervation and are therefore _____.
External; painful
A patient with hepatocellular carcinoma and tense ascites presents with mental status change and bright red blood per rectum. On physical exam, you see dilated veins but cannot deduce if they are painful given the patient’s mental status. What is the likely diagnosis of the rectal exam findings?
Internal hemorrhoids, which can result from portal hypertension
The apical surface of hepatocytes face which space?
The bile canaliculi
The basolateral surface of hepatocytes face what space?
The sinusoids
Describe the venous blood flow of the liver in order.
Portal circulation, portal vein, liver sinusoids, central vein, inferior vena cava
What fluid drains through the space of Disse in the liver?
Lymph (in the liver)
Describe bile flow through the liver.
Hepatocytes secrete bile via their apical surfaces into the bile canaliculi, which then drain into the bile ductule
Zone I of the liver is also known as the _______ zone.
Periportal
What structures are found in Zone I of the liver?
The portal triad (the portal vein, the portal artery, and the common bile duct)
Zone III of the liver is also known as what?
Pericentral vein zone (centrilobular zone)
What major structure is found in Zone III of the liver?
Branches of the central vein
Which zone of the liver contains the P450 enzyme system?
Zone III (pericentral vein/centrilobular zone)
Which zone is affected most by viral hepatitis?
Zone I
A patient presents with elevated alanine aminotransferase and aspartate aminotransferase levels with an alanine aminotransferase to aspartate aminotransferase ratio > 2.0. What zone of his liver is likely affected?
Zone III; alcoholic hepatitis usually affects Zone III
A patient presents with jaundice, encephalopathy, and oliguria. He has elevated liver enzymes. What zone of his liver is likely affected?
Zone III
Why is Zone II of the liver most affected by ischemia?
It is furthest away from the hepatic artery
Whereas portal veins drain from ____, the central vein drains to ____.
Splanchnic (gut) circulation; hepatic vein and systemic circulation
Liver sinusoids are lined with what kind of endothelium?
Fenestrated
Notably, the sinusoids of the liver are lacking what structure that most capillaries have?
Basement membrane
Why is it advantageous to have fenestrated capillaries in the liver sinusoids?
They allow macromolecules to have access to the hepatocytes, thereby facilitating appropriate metabolism of these macromolecules
En route from the liver sinusoids to the hepatocytes, plasma macromolecules must pass through what space?
The perisinusoidal space (the space of Disse)
A patient presents with right upper quadrant abdominal pain. Further work-up reveals a gallstone obstructing the common bile duct. Which two biliary ducts drain directly into the common bile duct?
The cystic duct and common hepatic duct
What is the name of the structure formed by the common bile duct and the pancreatic duct as they empty into the duodenum?
The ampulla of Vater
What is the name of the sphincter through which bile passes to enter the duodenum?
The sphincter of Oddi
Blockage of which biliary structure would cause a dilated gallbladder but no other blockage?
The cystic duct
A gallstone in what location would lead to elevated amylase and lipase as well as serum bilirubin and alkaline phosphatase?
Ampulla of Vater
A patient presents with right upper quadrant pain, fever, and jaundice. She has elevated liver enzymes but normal pancreatic enzymes. If a gallstone is the cause of these findings, where is it likely to be located?
In the common bile duct
What structure forms the superior border of the femoral triangle?
The inguinal ligament
What structure forms the lateral border of the femoral triangle?
The sartorius muscle
What structure forms the medial border of the femoral triangle?
The adductor longus muscle
What three main structures are contained within the femoral sheath?
Femoral artery, femoral vein, and femoral canal
What femoral triangle structure lies outside of the femoral sheath?
The femoral nerve
Going from lateral to medial, list the components that are found within the femoral triangle.
Nerve, artery, vein, empty space, lymphatics (remember: the contents lateral to medial are NAVEL as well as venous near the penis)
What is the site of protrusion of an indirect hernia into the inguinal canal?
The internal inguinal ring
Name the layers that compose the spermatic cord, from the most superficial to the deepest layer.
External spermatic fascia, cremasteric muscle and fascia, and internal spermatic fascia
From the most superficial layer to deep, what are the three muscles that cover the internal (deep) inguinal ring?
External oblique, internal oblique, and transversus abdominis
Between which two structures would you find a direct inguinal hernia?
The inferior epigastric vessels and the rectus abdominus
Diaphragmatic hernias in infants are often a result of the defective development of what membrane?
The pleuroperitoneal membrane
What type of inguinal hernia is seen in infants?
Indirect, especially in males
What is the difference between sliding and paraesophageal hernias?
Sliding hernias result in a displaced gastroesophageal junction, resulting in increased risk for gastroesophageal reflux disease, whereas paraesophageal hernias lead to displacement of the gastric cardia increasing risk of gastric incarceration
Which type of hiatal hernia is associated with gastroesophageal reflux disease refractory to medical treatment?
Sliding hernias result in a displaced gastroesophageal junction, resulting in increased risk for gastroesophageal reflux disease
What structures are displaced in a paraesophageal hernia?
The cardia of the stomach is displaced into the thorax whereas the gastroesophageal junction is unaffected
Trace the path of an indirect inguinal hernia.
Internal (deep) inguinal ring, through external (superficial) ring, into scrotum
What structure do both direct and indirect inguinal hernias pass through?
The external (superficial) inguinal ring
What structure is useful for spatially differentiating direct inguinal hernias from indirect inguinal hernias?
The inferior epigastric artery (remember: MDs don’t LIe: Medial to inferior epigastric artery = Direct hernia and Lateral to inferior epigastric artery = Indirect hernia to recall locations
An indirect inguinal hernia enters the internal inguinal ring _____ to the inferior epigastric artery.
Lateral
Indirect hernias occur in infants as a result of the failure of the _____ _____ to close.
Processus vaginalis
Which type of hernia is much more common among males?
The indirect inguinal hernia
A direct inguinal hernia bulges directly through the abdominal wall _____ to the inferior epigastric artery.
Medial
Which type of hernia usually occurs among older men?
The direct inguinal hernia
Hesselbach’s triangle is defined by what structures?
The inguinal ligament, rectus abdominus muscle, inferior epigastric artery
Relative to the pubic tubercle, where is a femoral hernia typically located?
Below and lateral to the pubic tubercle (through the femoral canal)
Are femoral hernias more common in men or women?
Women
What type of hernia is most likely to become incarcerated?
Femoral
How many layers of the spermatic cord cover the sac of an indirect hernia? A direct hernia?
Only the superficial layer; all layers
The G cells of the antrum produce which hormone?
Gastrin
From lateral to medial, list the five structures that are found in the femoral triangle.
Nerve, Artery, Vein, Empty space, Lymphatics (the contents lateral to medial are NAVEL )
