Hindgut and Associated Arteries, Liver, Gall Bladder and Biliary Tree Flashcards
Which artery supplies the hindgut?
Inferior mesenteric artery
At what vertebral level is the IMA given off?
L3
What components make up the hindgut?
Distal third of transverse colon, descending colon, sigmoid colon and rectum
Which vessels contribute to the formation of the marginal artery? What does it supply?
SMA: middle colic
IMA: left colic, sigmoid
Supplies area around splenic flexure
Aortic aneurysms can compress the IMA. Why doesn’t this impair gut function?
Due to collateral circulation supplied by the marginal artery
How is the sigmoid attached to the posterior body wall?
Sigmoid mesocolon
At what vertebral level does the sigmoid become the rectum?
S3
From the rectosigmoid junction, what changes can be seen in the structure of the hindgut?
Absence of taenia coli and appendices epiploicae
What is a sigmoid volvulus? Why is it a serious condition?
Obstruction of bowel due to twisting around sigmoid mesocolon
Can lead to chronic constipation, bowel ischaemia
The rectum runs from the __1__ to the __2__, about __3__ cm above the cutaneous margin of the anus
1) rectosigmoid junction
2) ano-rectal junction
3) 3
How many lateral curves are found in the rectum? What marks each curve on the interior?
Three
Each marked by a transverse fold or valve (2 on the left, middle one on the right)
What are the three main vessels (some may be paired) that supply the rectum?
Superior rectal
Middle rectal
Inferior rectal
From where does the superior rectal artery originate?
Inferior mesenteric artery
From where does the middle rectal artery originate?
Internal iliac
From where does the inferior rectal artery originate?
Internal pudendal
What is the definition of a portal vein? Are there any others (other than the hepatic portal vein)?
Blood vessel that takes blood from one capillary bed to a second prior to it entering the vena cava and returning to the heart.
Yes, around the pituitary gland
Which vessels unite behind the neck of the pancreas?
Superior mesenteric vein and splenic vein unite to form the hepatic portal vein
The hepatic portal vein is a continuation of which vessel?
Superior mesenteric vein
The portal vein runs in what structure?
Free edge of lesser omentum
What is the distribution of the inferior mesenteric vein?
Runs superiorly, well to the left of the IMA. Usually joins the splenic vein behind the body of the pancreas, just before the union of the splenic vein with the superior mesenteric vein.
The right gastric vein drains into which vessel?
Portal vein
The left gastric, short gastric, and left gastroepiploic veins drain into which vessel?
Splenic vein
The right gastroepiploic and superior pancreaticoduodenal veins drain into which vessel?
Superior mesenteric vein
What is the purpose of the portal circulation?
To allow blood carrying recently digested chyme to be processed by the liver prior to entering the general circulation
Where to the oesophageal veins drain?
Azygos system
Why is knowledge of the lymphatic drainage of the GI tract important?
Spread of metastasising cancer cells
What are the pre-aortic lymph nodes?
Coeliac, superior mesenteric and inferior mesenteric lymph nodes
True or false: The pre-aortic lymph nodes drain into one another, from below upwards
True
The coeliac lymph nodes drain into which channel? Where does it run and empty its contents?
Cisterna chyli
Empties into thoracic duct
Where does lymph from the rectum go?
Follows the middle rectal artery to the internal iliac lymph nodes
What are Peyer’s patches?
Areas of lymphoid tissue which are located within the walls of the small intestine
In which layers of the gut wall are the intrinsic (myenteric) nerve plexuses located?
Muscularis propria, between the submucosa and the serosa or adventitia
While most of the autonomic fibres to the gut travel via the coeliac plexus, parasympathetic fibres to the hindgut originate from __1__ and and travel via the __2__
1) sacral segments of the spinal cord
2) inferior hypogastric (pelvic) plexus
The coeliac plexus receives its parasympathetic input from what nerves?
Vagus nerves
The coeliac plexus receives sympathetic input from what nerves?
Splanchnic nerves
The splanchnic nerves arise from __1__ and enter the abdomen via the __2__
1) sympathetic chain
2) aortic hiatus
Where would a patient feel pain referred from the foregut?
Epigastric region
Where would a patient feel pain referred from the midgut?
Umbilical region
Where would a patient feel pain referred from the hindgut?
Hypogastric or pubic region
To which area is pain from the appendix referred?
Umbilical region
Why might pain from the gallbladder be referred to the shoulder?
If the pain reaches the diaphragm, then nerves C3-5 will be involved. This is the dermatome of the shoulder
What structure is found in the free edge of the falciform ligament?
Ligamentum teres (vestige of umbilical vein)
What structures pass through the porta hepatis?
Hepatic ducts (left and right)
Hepatic portal vein
Hepatic arteries
(NOT hepatic veins)
How many hepatic veins are usually found in the liver? Where do they drain into?
Usually 3
Drain into IVC
What structures provide anchoring for the liver?
Hepatic veins
Falciform ligament
Triangular ligament
What structures run in the free edge of the lesser omentum?
Hepatic artery (anterior left)
Bile duct (anterior right)
Hepatic portal vein (posterior)
Where does the common bile duct run after it leaves the lesser omentum?
Posterior to the duodenum and head of pancreas, to form the hepatopancreatic ampulla with the main pancreatic duct
What is the hepatopancreatic ampulla (of Vater) and where is the sphincter of Oddi?
Dilation where the bile duct and main pancreatic duct unite, it is surrounded by the hepatopancreatic sphincter (of Oddi). A smooth muscle sphincter so is under control of the ANS
If a gallstone became lodged at the sphincter of Oddi, which other organ would be affected?
Pancreas
Biliary obstruction can cause what symptoms? Why?
Jaundice, pale faeces, dark urine
Bile is reabsorbed into the bloodstream and deposited where the pressure is low (ie surface of the skin). Pale faeces are due to the lack of bile entering the GI tract and therefore colouring the faeces. As it is in the bloodstream it is filtered by the kidney darkening the urine.
What is the blood supply of the gallbladder? Where does it come from?
Cystic artery, from right hepatic artery
