Gastrointestinal ANATOMY Flashcards
What 2 vertical lines divide the abdomen into it’s 9 nine regions?
Mid-clavicular lines that extend to the mid-inguinal point.
What 2 horizontal lines divide the abdomen into it’s 9 nine regions?
Upper - Subcostal: joins lower costal margins.
Lower - Intertubercular: connects the iliac crests.
How would you draw the transpyloric plane?
Half way between the suprasternal notch and the pubic symphysis.
What vertebral level is the transpyloric plane found?
L1.
Name 5 structures found on the transpyloric plane.
- Pylorus of stomach.
- Fundus of gall bladder.
- Pancreas.
- Hilum of Kidneys.
- Duodenojejunal flexure.
How would you draw the transtubercular plane?
Joins the iliac crests of the pelvis.
What vertebral level is the transtubercular plane found at?
L4. (Same level as the bifurcation of the abdominal aorta).
What is the intercristal plane?
It joins the highest points of the pelvis at the back.
What vertebral level is the intercristal plane found at? Why is this important?
Between the L4 and L5 vertebrae. This is important for lumbar punctures and epidurals.
What is the subcostal plane and at what vertebral level does it lie?
It joins the lower points of the costal margins and lies at the L2 level.
What can the subcostal plane (L2) be a marker for?
- The end of the spinal cord.
- The superior mesenteric artery.
What is McBurney’s point?
2/3 of the way along a line extending from the umbilicus to the right anterior superior iliac spine.
What is the significance of McBurney’s point?
Marks the base of the appendix and can act as a guide for the location of the caecum.
Name the 3 flat muscles of the Abdominal wall.
- External Oblique.
- Internal Oblique.
- Transversus Abdominis.
In what direction do the fibres of the flat muscles run in?
- External oblique - inferiorly and medially (down and in).
- Internal oblique - superiorly and medially (up and in).
- Transversus abdominis - transversely.
What is the origin of external oblique?
Lower 8 ribs and thoraco-lumbar fascia.
What is the insertion of external oblique?
Pubic crest, pubic tubercle, iliac crest and linea alba.
What is the origin of internal oblique?
Thoraco-lumbar fascia, iliac crest, lateral 1/2 of the inguinal ligament.
What is the insertion of internal oblique?
Linea alba, pubic tubercle.
What is the origin of transversus abdominis?
Thoraco-lumbar fascia, iliac crest, lateral 1/3 of the inguinal ligament.
What is the insertion of transversus abdominis?
Linea alba, pubic tubercle.
What are the fibrous intersections of the rectus abdominis called?
Tendinous intersections.
What are the attachments of rectus abdominis?
Rectus sheath, pubis, costal cartilages.
Name 5 structures contained within the rectus sheath.
- Rectus Abdominis.
- Sup and inf epigastric arteries.
- Sup and inf epigastric veins.
- Nerves.
- Lymphatics.
What is the inferior epigastric artery a branch of?
The external iliac artery.
What is the internal thoracic artery a branch of? And what does it supply?
It is a branch of the subclavian artery and it supplies the anterior chest and abdominal wall and also the breasts.
Define dermatome.
An area of skin supplied by nerves from a single spinal root.
What are the dermatomes of the abdominal wall?
T7 to L1.
If a disease process involves the peritoneum of the abdominal wall, then the pain is localised. Why is this?
The peritoneum covering the inside of the abdominal wall has the same sensory nerve supply as the overlying skin.
What is the epithelium lining of the abdominal cavity?
Simple squamous epithelium.
Simple squamous epithelium.
A potential space between the visceral and parietal peritoneum. It is filled with peritoneal fluid.
What is a retroperitoneal organ?
An organ that only has it’s anterior surface covered by peritoneum. These organs lie behind the peritoneum.
Name 6 retroperitoneal organs.
Duodenum, ascending colon, descending colon, pancreas, oesophagus, kidneys. (DADPOK).
What is an intraperitoneal organ?
An organ fully covered in visceral peritoneum. It is suspended in the peritoneal cavity.
Name 6 intraperitoneal organs.
Sigmoid colon, appendix, liver, transverse colon, stomach, small intestine. (SALTSS).
What connects the lesser sac to the greater sac?
The epiploic foramen.
What does the lesser omentum attach to?
It extends from the liver and attaches to the lesser curvature of the stomach and the first part of the duodenum.
It extends from the liver and attaches to the lesser curvature of the stomach and the first part of the duodenum.
- Common bile duct.
- Hepatic artery.
- Hepatic portal vein.
Where is attached to the greater curvature of the stomach?
The greater omentum.
Describe the position and folding of the greater omentum in the peritoneal cavity.
It hangs down like an apron and then folds back on itself meaning there are 4 layers. The posterior 2 layers go on to enclose the transverse colon (transverse mesocolon) and then form the parietal peritoneum of the posterior abdominal wall.
What is it called when the peritoneal cavity becomes distended by fluid?
Ascites.
With a patient in a supine (lying down) position, where might fluid collect in the abdomen?
In the right retrohepatic space.
What embryological structure forms the ligamentum teres?
The umbilical vein.
Which structures surround the epiploic foramen?
- Anteriorly: lesser omentum.
- Posteriorly: IVC.
- Inferiorly: duodenum.
- Superiorly: caudate lobe of liver.
What connects the jejunum to the posterior abdominal wall?
Small intestine mesentery.
What parts of the large intestine are intraperitoneal?
The transverse and sigmoid colon.
Define lesser sac.
A peritoneal sac that lies posteriorly to the stomach and lesser omentum. It communicates with the greater sac through the epiploic foramen.
What lies in the free border of the lesser omentum?
The hepatic artery, hepatic portal vein and common bile duct.
What structures lie posteriorly to the stomach?
Pancreas, diaphragm, splenic artery and vein.
Name the 4 main regions of the stomach.
- Cardia.
- Fundus.
- Body.
- Pylorus.
What vertebral levels does the stomach lie between?
T7 to L3.
What are the folds of the internal stomach surface called?
Rugae.
Name the 2 sphincters of the stomach.
- Inferior oesophageal sphincter.
- Pyloric sphincter.
Which sphincter of the stomach is physiological (containing no sphincteric muscle)?
The inferior oesophageal sphincter.
What forces act on the inferior oesophageal sphincter?
- The diaphragm exerts a pressure on the hiatus.
- The lumen is collapsed in the normal state.
- The oesophagus enters the stomach at a right angle; when the stomach is full this is closed off.
What is the function of the pyloric sphincter?
Controls the exit of chyme from the stomach.
What vertebral level is the coeliac trunk found?
T12.
Where does the foregut begin and end?
The mouth to the 2nd part of the duodenum (major duodenal papilla).
What is the blood supply to the greater curvature of the stomach?
The short gastrics, and the right and left gastro-epiploic arteries.
What is the blood supply to the lesser curvature of the stomach?
The left and right gastric arteries.
What is the right gastric artery a branch of?
The proper hepatic artery which arises from the common hepatic artery from the coeliac trunk.
What is the right gastro-epiploic artery a branch of?
It is the terminal branch of the gastroduodenal artery, this arises from the common hepatic artery which arises from the coeliac trunk.
What is the left gastro-epiploic artery a branch of?
The splenic artery which arises from the coeliac trunk.
What vein does venous blood from the GI tract, liver and spleen drain into?
The hepatic portal vein (goes to the liver).
What supplies sympathetic innervation to the stomach (foregut)?
The greater splanchnic nerve (T5-T9).
What supplies parasympathetic innervation to the stomach (foregut)?
The Vagus nerve Cn 10.
Is contraction of the stomach sphincters a sympathetic or parasympathetic action?
Sympathetic. (Parasympathetic = rest and digest).
At what vertebral level does the oesophagus pass through the stomach?
T10.
What structures pass through the diaphragm along side the oesophagus?
Vagus nerves and the oesophageal arteries and veins.
What does the left gastric artery supply?
The superior part of the lesser curvature of the stomach.
What structures lie anterior to the stomach?
The anterior abdominal wall and the left lobe of the liver.
What nerve lies anterior to the abdominal oesophagus and which posterior?
Left vagus - anterior.
Right vagus - posterior.
(LARP)
What are the 3 divisions of the small intestine called?
- Duodenum.
- Jejunum.
- Ileum.
What is the principle function of the small intestine?
Digestion and absorption of food.
What are the folds of mucosa inside the small intestine called?
Plicae circulares.
What are Peyer’s patches?
Large, sub-mucosal, lymph nodules.
Where in the small intestine would you find Peyer’s patches?
Ileum.
Is the duodenum intraperitoneal or retroperitoneal?
Retroperitoneal.
The first part of the duodenum is prone to peptic ulceration. What artery can this affect?
The gastro-duodenal artery. This artery lies in direct contact with the posterior wall of the first part of the duodenum.
Would you describe the jejunum and ileum as intraperitoneal or retroperitoneal?
Intraperitoneal.
What part(s) of the small intestine can become twisted? This results in strangulation and ischaemia.
Jejunum and ileum.
Which has a thicker intestinal wall, the jejunum or the ileum?
Jejunum.
Describe 5 characteristics of the Jejunum.
- Thick intestinal walls.
- Longer vasa recta.
- Less arterial arcades.
- Pronounced plicae circulares.
- Red in colour.
Describe 5 characteristics of the Ileum.
- Thin intestinal walls.
- Shorter vasa recta.
- More arterial arcades.
- Peyer’s patches.
- Pink in colour.
Where might you find Meckel’s diverticulum?
1 meter from the termination of the ileum.
What is Meckel’s diverticulum an embryonic remnant of?
The attachment of the mid-gut to the yolk sac.
Where does the mid-gut begin and end?
3rd part of duodenum to 2/3 along the transverse colon.
What is the blood supply to the midgut?
Superior mesenteric artery (L1).
What is the first branch of the SMA?
Inferior pancreaticoduodenal artery?
Name 3 major branches of the SMA.
- Ileocolic.
- Right colic.
- Middle colic.
What does the right colic artery supply?
The ascending colon.
What does the middle colic artery supply?
The transverse colon.
Into which vein does blood from the jejunum and ileum drain and what is the final destination of the blood?
Drains into the superior mesenteric vein.
This vein combines with the splenic vein to form the hepatic portal vein which then goes on to the liver.
Which foodstuffs are absorbed through the lymphatic system?
Fats.
What is the innervation of the small intestine?
Sympathetic: Lesser splanchnic (T10-11). Parasympathetic: Vagus. No somatic innervation.
Name 4 mechanisms that ensure a high surface area for absorption of nutrients in the intestine.
- Pliae circularis.
- Coiled length.
- Villi.
- Microvilli.
What is the main function of the large intestine?
Water absorption and the formation of faeces.
State whether the caecum is intraperitoneal or retroperitoneal and describe the blood supply and venous drainage.
- Intraperitoneal.
- Ileocolic artery.
- Ileocolic vein; drains into superior mesenteric vein.
State whether the ascending colon is intraperitoneal or retroperitoneal and describe the blood supply and venous drainage.
- Retroperitoneal.
- Ileocolic and right colic arteries.
- Ileocolic and right colic veins.
State whether the transverse colon is intraperitoneal or retroperitoneal and describe the blood supply and venous drainage.
- Intraperitoneal.
- Middle colic artery.
- Superior mesenteric vein.
State whether the descending colon is intraperitoneal or retroperitoneal and describe the blood supply and venous drainage.
- Retroperitoneal.
- Left colic and superior sigmoid arteries.
- Inferior mesenteric vein.
State whether the sigmoid colon is intraperitoneal or retroperitoneal and describe the blood supply and venous drainage.
- Intraperitoneal.
- Sigmoid arteries.
- Inferior mesenteric vein.
What is the marginal artery of Drummond?
An artery that forms important anastomosis between SMA and IMA. It extends the length of the colon.
What vertebral level is the inferior mesenteric artery found at?
L3.
Name 3 characteristic features of the large intestine that allow it to be distinguished from other abdominal organs.
- Haustrations.
- Tenia coli.
- Appendices epiploicae.
What are appendices epiploicae?
Small pouches of peritoneum filled with fat. They mark where blood vessels enter the bowel to supply the mucosa.
What are tenia coli?
3 strips of longitudinally running muscle on the outer surface of the large intestine.
What are haustrations?
Sacculations produced from where the tenia coli contract to shorten the wall of the bowel.
Where does the hind gut begin and end?
Distal 1/3 of the transverse colon to the anal canal.
What is the innervation of the hind gut?
Sympathetic: least splanchnic nerve (T12). Parasympathetic: S2-4. No somatic innervation.
What artery normally supplies the descending colon?
The left colic artery.
What is the importance of the marginal artery of Drummond?
If there is an occlusion to the IMA, blood can still be supplied to the large intestine via the SMA through this artery.
Give 4 locations where the distal end of the appendix may lie.
- In the pouch of Douglas.
- Behind the caecum.
- Behind the umbilicus.
- Below the liver.
Name the intraperitoneal parts of the large intestine.
Caecum, transverse colon, sigmoid colon.
Give 4 functions of the liver.
- Synthesis of bile.
- Glycogen storage.
- Clotting factor production.
- Detoxification of blood.
What is the liver an embryological derivative of and in which mesentery does it develop?
Derivative of the foregut. Develops in the ventral mesentery.
What structure(s) lie anterior to the liver?
The rib cage and the anterior abdominal wall.
What structure(s) lie superior to the liver?
The diaphragm.
What structure(s) lie posterior to the liver?
Oesophagus, stomach, gall bladder, first part of duodenum. (All are foregut derived organs).
What aspects of the liver does the diaphragmatic surface refer to?
The anterior superior aspects. This surface is smooth and convex.
What aspects of the liver does the visceral surface refer to?
The posterior inferior aspects. It is moulded by the shape of surrounding organs and so is irregular.
The posterior inferior aspects. It is moulded by the shape of surrounding organs and so is irregular.
- The falciform ligament.
- The right and left coronary ligaments.
- The right and left triangular ligaments.
What is the function of the falciform ligament?
To attach the liver to the anterior abdominal wall.
What is found in the free edge of this ligament?
The ligamentum teres (remnant of the umbilical vein).
What is the function of the coronary and triangular ligaments?
They attach the superior surface of the diaphragm to the liver.
Name the 4 lobes of the liver.
- Right.
- Left.
- Caudate.
- Quadrate.
What structures bind the Caudate lobe and where is it located?
The IVC and a fossa produced by the ligamentum venosum. It is located on the upper aspect of the right lobe on the visceral surface.
What structures bind the Quadrate lobe and where is it located?
The gall bladder and a fossa produced by the ligamentum teres. It is located on the lower aspect of the right lobe on the visceral surface.
What divides the liver into the right and left lobes?
The falciform ligament.
What vein supplies the liver with dexoygenated blood?
The hepatic portal vein.
What vein supplies the liver with oxygenated blood?
The hepatic artery proper.
What is the function of the gall bladder?
A temporary storage for bile.
What is the storage capacity of the gall bladder?
30-50ml.
What are the 3 divisions of the gall bladder?
Fundus, body and neck. The neck is where the gall bladder tapers and becomes continuous with the cystic duct.
Briefly describe the biliary tree.
Left and right hepatic ducts = common hepatic duct.
Common hepatic duct + cystic duct = common bile duct. Common bile duct + pancreatic duct = hepatopancreatic ampulla of Vater.
What is it called where the common bile duct and pancreatic duct meet?
The hepatopancreatic ampulla of Vater.
What is the orifice called where bile empties into the duodenum?
The major duodenal papilla.
What sphincter regulates the emptying of bile into the duodenum?
The sphincter of Oddi.
What artery supplies blood to the gall bladder?
The cystic artery.
Does parasympathetic or sympathetic innervation result in contraction of the gall bladder and the secretion of bile?
Parasympathetic.
What is the arrangement anterior to posterior of the ducts, artery and portal vein at the porta hepatis?
Anterior: Common bile duct, hepatic artery, hepatic portal vein. (DAV)
What is Calot’s triangle?
An anatomic space bounded by the liver superiorly, the cystic duct laterally and the common hepatic duct medially.
What is the cystic artery a branch of?
The right hepatic artery - hepatic artery proper - common hepatic artery - coeliac trunk.
Where is the bare area of the liver?
Under the tendinous part of the right hemi-diaphragm. This area has no peritoneal covering.
What is the surface marking for the gall bladder?
The tip of the 9th costal cartilage. Where the lateral rectus sheath joins the costal margin.
Where do the hepatic veins drain?
Into the IVC.
What are the 3 major branches of the Coeliac trunk?
The left gastric, the splenic and the common hepatic.
What does the left gastric artery supply?
The lesser curvature of the stomach and lower oesophagus.
What branches does the splenic artery give off?
- The short gastric arteries.
- The pancreatic arteries.
- The left gastroepiploic artery.
- 5 branches just before it reaches the Spleen.
What do the short gastric arteries supply?
The greater curvature of the stomach.
What does the left gastroepiploic artery supply? What does anastomose with?
It supplies the greater curvature of the stomach. It anastomoses with the right gastroepiploic artery.
Name the 2 branches of the common hepatic artery.
- Proper hepatic artery.
- Gastroduodenal artery.
Name the 2 branches of the Gastroduodenal artery.
- Right gastroepiploic artery (supplies greater curvature of the stomach).
- Superior pancreaticoduodenal artery (supplies head of pancreas).
Name the 3 branches of the proper hepatic artery?
- Right hepatic artery.
- Left hepatic artery.
- Right gastric artery.
What does the right gastric artery supply?
The lesser curvature of the stomach.
What is a branch of the right hepatic artery?
The cystic artery (supplies the gall bladder).
Name the 4 divisions of the Duodenum.
- Superior.
- Descending.
- Inferior.
- Ascending.
Where in the duodenum are ulcers most likely? And which artery would they affect?
Most likely in the superior duodenum (1st part). If the ulcers erode through the posterior wall they may effect the gastroduodenal artery and cause haemorrhage.
What does the descending portion of the Duodenum lie posteriorly and anteriorly to?
Posteriorly to transverse colon. Anteriorly to the right kidney.
What vessels lie anteriorly to the inferior part of the duodenum? (3rd part)
The superior mesenteric artery and vein.
Is the duodenum retroperitoneal or intraperitoneal?
The duodenal cap is intraperitoneal but the rest of the duodenum is retroperitoneal.
Is the pancreas retroperitoneal or intraperitoneal?
The tail is intraperitoneal but the rest of the pancreas is retroperitoneal.
Name the 5 parts of the Pancreas.
- The head.
- The uncinate process.
- The neck.
- The body.
- The tail.
What does the tail of the pancreas lie in close proximity to?
The hilum of the spleen.
Why can diseases of the pancreas spread to adjacent tissues?
Because it isn’t contained within a capsule.
What is the blood supply to the head of the pancreas?
The superior and inferior pancraticoduodenal arteries.
What is the superior pancraticoduodenal artery a branch of?
The gastroduodenal artery.
What is the inferior pancraticoduodenal artery a branch of?
The SMA.
What is the blood supply to the rest of the pancreas?
Pancreatic branches of the splenic artery.
What is the venous drainage of the pancreas?
The head drains into the SMV (drains into hepatic portal vein). the pancreatic veins drain the rest of the pancreas (these drain into the splenic vein).
What is the function of the spleen?
In an adult it functions mainly as a blood filter, removing old RBC’s from circulation.
Is the spleen intraperitoneal or retroperitoneal?
Intraperitoneal.
What ligaments of the greater omentum connect the spleen to the stomach and kidney?
Gastrosplenic and Splenorenal.
How far away is the major duodenal papilla from the pylorus of the stomach?
5cm.
What is the embryological significance of the major duodenal papilla?
It marks the junction between the foregut and the midgut.
What is the importance of the plicae circularis?
They increase the intestinal SA available for absorption.
What is the dermatome of the umbilicus?
T10.
You are examining a patient with a large spleen. How do you know on examination that you are palpating the spleen?
- Located in the upper left quadrant.
- Unable to feel an upper border on palpitation.
Hypertrophy of the pyloric sphincter can cause what?
Vomiting of gastric contents.
What is the appendicular artery a branch of?
The ileocolic artery (branch of SMA).
