GI Flashcards
approximately how long is the oesophagus?
25cm
from which vertebral levels does the oesophagus extend?
C6-T11
what two parts can the oesophagus be divided into?
thoracic and abdominal
what level does the oesophagus pierce the diaphragm?
T10
which ligament connects the oesophagus to the border of the oesophageal hiatus?
the phrenicoesophageal ligament
what are the three muscular layers of the oesophagus and are they voluntary or smooth muscle?
-superior third- voluntary striated -middle third- voluntary striated and smooth muscle -inferior third- smooth muscle
what level does the oesophagus enter the stomach?
T11
which of the oesophageal sphincters is anatomical?
upper
which of the oesophageal sphincters is physiological?
lower
what forces cause the lower oesophageal sphincter?
-acute angle -positive intra abdominal pressure -folds of the mucosa present -the right crus of the diaphragm has a ‘pinch cock’ effect
what arteries supply the thoracic part of the oesophagus?
-branches of the thoracic aorta and the inferior thyroid arteries
what veins supply the thoracic part of the oesophagus?
azygous veins and the inferior thyroid veins
what arteries supply the abdominal section of the oesophagus?
left gastric artery and left inferior phrenic nerve.
in what two ways is the venous drainage of the abdominal part of the oesophagus supplied?
-to the portal circulation via the left gastric vein -the the systemic circulation via the azygous vein
what is the clinical significance of the different venous drainage of the oesophagus.
it drains into the portal circulation, so when the intra hepatic pressure increases (like in liver failure) the veins can be damaged- oesophageal varicies
what is barrettes’ oesophagus?
metaplasia of lower oesophagus squamous epithelia to gastric columnar epithelia. Usually due to chronic acid exposure.
what are the two major types of oesophageal carcinoma?
-squamous cell carcinoma -adenocarcinoma
where is it most likely to find an adenocarcinoma of the oesophagus? (except from the oesophagus smart ass)
-inferior 1/3 -associated with barrettes’ oesophagus
where is it most likely to find a squamous cell carcinoma of the oesophagus?
any level !
between which vertebral levels does the stomach extend?
T7-L3
what are the 4 main sections of the stomach?
-cardia -fundus -body -pylorus
what arteries supply the greater curvature of the stomach?
the short gastric arteries, the right and left gesture-omental arteries.
Which ligament attaches to the lesser curvature of the stomach and what travels within it?
hepatogastric ligament with the hepatic triad within.
which arteries supply the lesser curvature of the stomach?
left gastric artery and right gastric branch of the hepatic artery.
where is the pyloric sphincter located?
between the pylorus and duodenum
what is the role of the pyloric sphincter?
controls the exit of chyme from the stomach
is the pyloric sphincter an anatomical or physiological sphincter?
anatomical
what characteristic of the pyloric sphincter makes sure food stays in the stomach for a suitable amount of time?
the pylorus in normally tonically contracted so the orifice is small
why is the greater omentum often called the policeman of the abdomen?
it contains lymph nodes and macrophages which help combat infections and wall off infections in the abdomen.
what is the main function of the lesser omentum?
attach the stomach and duodenum to the liver
what do the omen separate the abdomen into?
the greater and lesser sacs
through what structure do the greater and lesser sacs communicate?
the epiploic foramen
which arteries supply the stomach?
-right gastric -left gastric -right gastro-omental -left gastro-omental
which nerve supplies the parasympathetic innervation of the stomach?
posterior vagal trunks derived from the vagus nerve
which nerve supplies the sympathetic innervation of the stomach?
T6-T9 spinal cord segment
what six cells are found in the stomach and what do they secrete?
-mucous neck cells-mucus -parietal cells-HCL and intrinsic factor -enterochromaffin cells-histamine -chief cells- pepsinogen and lipase -D cells- somatostatin -G cells- Gastrin
what are the effects of gastrin?
-stimulates parietal cells to secrete HCL -stimulates chief cells to secrete pepsinogen -contracts the lower oesophageal sphincter -increases stomach motility -relaxes pyloric sphincter -digestion
What is GORD?
-Gastro-osophageal reflux disease -gastric acid and food moves past the lower oesophageal sphincter into the oesophagus
what are the common symptoms of GORD?
-chronic heartburn -dysphagia -unpleasant sour taste in the mouth
what are the three main causes of reflux disease?
-dysfunction of the lower oesophageal sphincter -delayed gastric emptying -hiatal hernia
what are the methods of treatment of GORD?
-lifestyle changes -medication -surgery as a last resort
give a brief description of a hiatus hernia.
when part of the stomach protrudes into he chest through the oesophageal hiatus in the diaphragm.
what are the two types of hiatus hernia?
-sliding hernia- lower oesophageal sphincter slides superiorly -rolling hernia- the lower oesophageal sphincter remains in place, but a part of the stomach herniates into the chest next it
where do the four sections of the duodenum lie in relation to the vertebrae?
-superior-L1 -descending-L1-L3 -inferior-L3 -Ascending-L3-L2
which part of the duodenum are duodenal ulcers most common?
Superior
what marks the descending duodenum?
the major duodenal papilla and sphincter of oddi
which part of the duodenum crosses the aorta and vena cava?
inferior
what vessel passes anteriorly to the front of the inferior duodenum?
SMA
which muscle decreases the angle of the duodenojunal flexure and thus helps movement of intestinal contents into the jejunum?
suspensory muscle of the duodenum
what forms the ilioceacal valve?
ileum invaginate into the ceacum
which of the jejunum and ileum have longer vasa recta?
jejunum
which of the jejunum and ileum have more arcades?
ileum
what are the two most common causes of duodenal ulcers?
-helicobacter pylori infection -chronic NSAIDs
which two arteries supply the duodenum?
-initial part- gasproduodenal artery -distal to the duodenal papilla- inferior pancreaticoduodenal
what does the change in blood supply of the duodenum signify?
the change from the embryological foregut to midgut
which artery supplies the jejunum and ileum?
SMA
which vain drains the jejunum and ileum?
superior mesenteric vein
which vein combines with the SMV to form the hepatic portal vein?
the splenic vein
what are the four sections that the large intestine can be split into?
-cecum and appendix -colon -rectum -anal canal
what are the three tenia coli which can be located on the large bowel?
-free tenia -mesenteric tenia -omental tenia
what is the action of the tenia coli?
contract to shorten the wall of the bowel, producing sacculations known as haustra.
what artery supplies the caecum?
ileocolic artey
which vein drains the caecum?
ileocolic artery
what is the appendix?
acute inflammation of the appendix?
where in the abdomen is most tender in appendicitis?
-McBurneys point -1/3 of the distance from the right anterior superior iliac spine to the umbilicus.
what are the four parts of the colon?
ascending, transverse, descending and sigmoid
what is the change of angle in the colon in the RUQ called?
hepatic flexure (right colic flexure)
what is the change of angle in the colon in the LUQ called?
splenic flexure (left colic flexure)
what are the spaces lateral to and between the ascending and descending colon and the abdominal called?
the left and right parabolic gutters
what is the marginal artery of the colon?
form anastomosis between the superior and inferior mesenteric arteries
what is the arterial supply and venous drainage of the transverse colon?
-artery-ileocolic and right colic (branches of the SMA) -vein-ileocolic and right colic (branches of the SMV)
what is the arterial supply and venous drainage of the ascending colon?
-artery- middle colic -vein- SMV
what is the arterial supply and venous drainage of the descending colon?
-artery- left colic and superior sigmoid (branches of the IMA) -vein- IMV
what is the arterial supply and venous drainage of the sigmoid colon?
-artery-sigmoid arteries (branch of the IMA) -vein- IMV
why is the marginal artery clinically important?
it provides collateral supply to the colon, maintaining blood supply in the case of occlusion or stenosis of one of the major arteries. It also means that if the colon is damaged, there will be a lot of bleeding!
what is the most distal portion of the colon?
the rectum
at what vertebral level does the rectum begin?
S3
where is the pouch of douglas?
-in women -formed between the posterior wall of the uterus and the colon
where is the retro-vesicle pouch?
-in men -between the posterior wall of the bladder and the colon
what is the clinical significance of the retro-uterine/vesicle pouch?
it’s the most inferior portion of the peritoneum, so any fluid in the peritoneal cavity accumulates there and can be sampled for diagnosis.
what are the subphrenic spaces?
recesses in the greater sac of the peritoneal cavity between the anteriosuperior diaphragmatic surface of the liver and the diaphragm.
what separates the subphrenic spaces?
the falciform ligament of the liver
why are subphrenic abscesses more common on the right side?
increased frequency of appendicitis and ruptured duodenal ulcers.
what are the two main roles of peritoneal fluid?
-lubricant, enabling free movement of the abdominal viscera -leukocytes and antibodies fight infection
why is the peritoneal space known as a potential space?
it’s usually only of capillary thinness, but it can fill up with excess fluid resulting in ascites.
where can the lesser sac be found?
posterior to the stomach and lesser omenta?
what divides the greater sac in two again?
mesentery of the transverse colon (transverse mesocolon)
where is the supra colic compartment and what does it contain?
lies above the transverse mesocolon and contains the stomach, liver and spleen
where is the infra colic compartment and what does it contain?
lies below the transverse mesocolon and contains the small intestine, ascending and descending colon.
what structures connect the supra colic and infra colic compartments?
the parabolic gutters
where is the epiploic foramen located?
posterior to the free edge of the lesser omentum (the hepatoduodenal ligament?
the peritoneal cavity is closed of to the outside, true or false?
false, in females the abdominal ostia of the uterine tubes open up into the peritoneal cavity providing a potential pathway between the female genital tract and the peritoneum.
why is it rare for infections to pass through the female genital tract to the peritoneum?
the mucous plug in the external os.
what is culdocentesis?
-extraction of fluid from the retrouterine pouch -through a needle inserted through the posterior fornix of the vagina -can be used to drain a pelvic abscess
what is paracentesis?
-drainage of fluid from the peritoneal cavity -a needle is inserted through the anterolateral abdominal wall into the peritoneal cavity. -the needle is inserted superior to the urinary bladder and avoiding the epigastric artery -used to drain ascitic fluid, diagnosis and to check for metastasis e.g. from liver cancer
what is ascites?
accumulation of excess fluid in the peritoneal cavity.
what are some potential causes of ascites?
can occur in conjunction with infection and peritonitis, however it’s more commonly caused by portal hypertension secondary to liver disease.
what epithelia forms the two layers of the peritoneum?
simple squamous epithelial cells -mesothelium
what are the two layers of the peritoneum?
-parietal -pleural
from what embryonic tissue is the parietal pleura derived?
somatic mesoderm
what sensations is the parietal peritoneum sensitive to?
pressure, pain, laceration and temperature
where does the parietal peritoneum attach?
the abdominopelvic wall
what does the visceral peritoneum attach?
invaginates to cover the majority of the abdominal viscera
from what embryonic tissue is the visceral pleura derived?
splanchnic mesoderm
what sensations is the visceral peritoneum sensitive to?
stretch and chemical irritation
where is pain from the parietal peritoneum referred?
it has the same somatic innervation as the region it lines, so pain is well localised.
where is pain from the visceral peritoneum referred?
areas of skin (dermatomes) which ares supplied by the same sensory ganglia and spinal cord segments as the nerve fibres innervating the viscera.
when can an organ be classed as an intraperitoneal organ?
when it’s completely covered in visceral peritoneum, anteriorly and posteriorly. e.g. stomach, liver and spleen
what can retroperitoneal organs be further subdivided into?
-primary retroperitoneal- develop and remain outside of the parietal peritoneum -secondary retroperitoneal-intitially intraperitoneal, suspended by mesentery, but they become retroperitoneal, with their mesentery fusing with the posterior abdominal wall.
which viscera are retroperitoneal?
S-suprarenal glands A- aorta/IVC D-duodenum P- pancreas U-ureters C-colon K-kidneys E-(o)esophagus R-rectum
what are peritoneal reflections?
double layers of peritoneum caused by the highly folded nature of the peritoneum.
what’s contained in the mesentery ?
it provides a pathway for nerves, blood vessels and lymphatics from the body wall to the viscera
what are the 5 ligaments around the stomach/spleen?
-lesser omentum -greater omentum -gastrophrenic ligament -gastrosplenic ligament -splenorenal ligament
why is pain referred?
-pain from the viscera is poorly localised -it’s referred to areas of the skin (dermatomes) which are supplied by the same sensory ganglia and spinal cord segments as the nerve fibres innervating the viscera.
where is pain from the foregut structures referred to?
epigastric region
where is pain from the midgut structures referred to?
umbilical region
where is pain from the hindgut structures referred to?
pubic region
where is pain from the retroperitoneal structures referred to?
the back
which structures are derived from the embryonic foregut?
-oesophagus -stomach -pancreas -liver -gallbladder -duodenum (proximal to the papilla)
which structures are derived from the embryonic midgut?
from the duodenum (distal to the papilla) to the junction of the proximal 2/3 of the transverse colon with the distal 1/3.
which structures are derived from the embryonic hindgut?
it extends from the distal 1/3 of the transverse colon to the upper part of the anal canal
where can irritation of the diaphragm be referred to?
the shoulder tip
describe the characteristic pattern of pain in appendicitis.
-initially pain from the appendix and visceral peritoneum is referred to the umbilical region. -as the appendix becomes inflamed and irritates the parietal peritoneum the pain becomes localised to the right lower quadrant.
what and where is the inguinal canal?
-short passage extending inferiorly and medially, through the inferior part of the abdominal wall. -superior and medial to the inguinal ligament -pathway for structures to and from the external genitalia
which is more superior, the deep inguinal ring or the superficial inguinal ring?
deep inguinal ring
what is the gubernaculum?
a fibrous cord of tissue which attaches the inferior portion of the gonad to the future scrotum, and guides them during their descent.
what is the processus vaginalis?
an embryonic outputting of peritoneum into the inguinal canal which usually degenerates.
failure of the processus vaginalis to regress can lead to what condition?
indirect inguinal hernia
where is the gubernaculum in the female?
-the ovaries are attached to the uterus by the gubernaculum, they are prevented from descending as far as the testes, instead moving into the pelvic cavity. -it then becomes the ovarian ligament, and round ligament of the uterus.
what is the mid-inguinal point and why is it important??
-halfway between the pubic symphysis and the anterior superior iliac spine. -the femoral artery crosses into he lower limb at this point.
what is the mid point of the inguinal ligament and why is it important?
-duh -runs from the pubic tubercle to the asis -opening of the inguinal canal is located just above this point.
what are the borders of the inguinal canal?
-anterior wall- aponeurosis of the external oblique, and reinforced by the internal oblique muscle laterally. posterior wall- transversalis fascia. -roof - transversalis fascia, internal oblique and transversus abdominis. -floor- inguinal ligament (a ‘rolled up’ portion of the external oblique aponeurosis) and thickened medially by the lacunar ligament.
during periods of high intra-abdominal pressure what stops inguinal herniation?
the muscles of the anterior and posterior wall contract, and ‘clamp down’ on the canal
what structures create the deep inguinal ring?
created by the transversalis fascia, which invaginates to form a covering of the contents of the inguinal canal
label the colours on this diagram of the inguinal canal.
there would be a picuture here, but
what passes throught the inguinal canal in women?
round ligament of the uterus
what passes through the inguinal canal in males?
the permatic cord
what are the two types of inguinal hernia?
- Indirect- where to peritoneal sac enters the inguinal canal through the deep inguinal ring
- direct- where the peritoneal sac enters the inguinal canal through the posterior wall of the inguinal canal
what causes an indirect inguinal hernias?
failure of the processus vaginalis to regress
what causes a direct inguinal hernia?
weakening in the abdominal musculature
What are the 5 main roles of the abdominal wall?
- keeps the abdominal viscera in the abdominal cavity
- protects the abdominal viscera from injury
- maintains the anatomical position of the viscera against gravity
- assists in forceful expiration by pushing the abdomnal viscera upwards
- involved in any action (coughing, vomiting) that increases intra-abdominal pressure.
What are the 4 layers of the abdominal wall?
skin, superficial fascia, muscles and parietal peritoneum
What is the composition of the superficial fascia above the umbilicus?
- a single sheet of connective tissue
- continuous with the superficial fascia of other parts of the body
what is the composition of the superficial fascia below the umbilicus?
- fatty superficial layer (camper’s fascia)
- membranous deep layer (scarpa’s fascia)
- superficial vessels and nerves run between the two layers
the muscles of the abdominal can be split into two categories, what are they?
the vertical muscles and the flat muscles.
what are the three flat muscles of the abdominal wall?
- external oblique
- internal oblique
- transversus abdominis
what are the actions of the flat muscles of the abdominalw all?
flex, laterally flex and rotate the trunk
which direction do the fibres of external oblique run?
inferomedially
what does external oblique become as they enter the midline?
aponeurosis
what is the linea alba?
the aponeurosis of all of the flat muscles combine int he mid-line and become entwined.
it’s a fibrous structure which runs from the xiphoid process of the sternum to the pubic symphysis.
in which direction do the fibres of internal oblique run?
superiormedially
what direction do the fibres of transversus oblique run?
transversely
what splits the rectus abdominus in two?
linea alba
what is the linea sumilunaris?
the lateral borders of the rectus abdominus muscle
what structures intersect the rectus abdominus in multiple places?
tendinous intersections
what is the action of rectus abdominus?
along with the other abdominal muscles it compresses the abdominal viscera, it also stabilises the pelvis during walking, and depresses the ribs.
where is the pyramidalis and what is it’s action?
- a triangular muscle with its base on the pubis bone
- the apex is attached to the linea alba
- acts to tense the linea alba
what forms the anterior wall of the rectus sheath?
the aponeurosis of the external oblique, and half of the internal oblique
what forms the posterior wall of the rectus sheath?
aponeuroses of half the internal oblique and of the transversus abdominus
where does all of the aponeuroses move to the anterior wall of the rectus sheath?
midway between the umbilicus and the pubic symphysis, known as the arcuate line.
below the arcuate line what is in contact with the posterior of the rectus abdominus?
transversalis fascia
what is the transpyloric plane?
horizontal line midway between the xiphoid process and the umbilicus, passing through the pylorus of the stomach.
what is the intertubecular plane?
horizontal line that joins the iliac crests.
what’s the role of the gall bladder?
used as a temporary store for bile fluid produced in the liver.
in what region of the abdomen is the gall bladder found?
right hypochondriac region
what’s the storage capacity of the gall bladder?
30-50ml
describe the biliary tree
- starts with the right and left hepatic ducts forming the common hepatic duct
- the cystic duct joins forming the common bile duct
- the pancreatic duct joins and forms the hepatopancreatic ampulla of vater
- it then empties into the duodenum via the major duodenal pampilla via the sphincter of oddi
what artery supplies the gallbladder?
cystic artery
what vein drains the gall bladder?
cystic vein
what are the basic functions of the liver?
bile synthesis, glycogen storage and clotting factor production
which abdominal regions can the liver be found?
right hypochondrium and epigastric areas, extending into the left hypochondrium
what are the two surfaces of the liver?
diaphragmatic and visceral
what is the ‘bare area’ of the liver?
a section of the liver which isn’t covered in by visceral peritoneum
what are the 4 ligaments from the liver and what do they connect?
- falciform ligament- join the anterior surface of the liver ot the anterior abdominal wall.
- coronary ligaments (left and right)- attach the superior surface of the liver to the diaphragm.
- triangular ligaments (left and right)- attach the superior surface of the liver to the diaphragm.
- lesser omentum-consists of the hepatoduodenal ligament and the hepatogastric ligament
what does the free edge of the falciform ligament contain?
ligamentum teres- a remnant of the umbilical vein
what are the three hepatic recesses?
- subphrenic spaces (left and right)- between the diaphragem and the liver, either side of the falciform ligament
- subhepatic space- between the inferior surface of the liver and the transverse colon.
- Morrison’s pouch- between the visceral surface of the liver and the right kidney
what is the clinical significance of morrison’s pouch?
it’s the deepest part of the peritoneal cavity when supine, this is where fluid is likely to collect in a bedridden patient.
what are the four lobes of the liver?
right and left lobe, the caudate and quadrate lobe
what is the fibrous layer that surrpouns the liver called?
Glissions capsule
