Hulka Flashcards
Which section is the shortest portion of the small bowel? What are the boundaries of this portion of bowel?
Dudoenum
Begins @ pylorus of stomach & ends at ligament of Trietz (this is the beginning of the jejunum)
What are the 3 branches off of the celiac trunk?
left gastric
common hepatic
splenic
Is the duodenum intraperitoneal or retroperitoneal?
The first 2-3 cm are intraperitoneal…
the rest of the duodenum is retroperitoneal.
How many divisions are there to the duodenum?
4
Where is the ligament of Treitz found?
This is a suspensory muscle that marks the division b/w the duodenum & the jejunum.
What is the first portion of the duodenum?
This is the 2-3 cm that is intraperitoneal. It begins after the pylorus.
It is also referred to as the duodenal bulb.
What 3 vessels run behind the first part of the duodenum?
common bile duct
gastroduodenal artery
IVC
What is the clinical significance of the first portion of the duodenum?
This is the site for duodenal ulcer disease.
They can develop here b/c of the increased acidity of the stuff leaving the stomach & going straight here.
What are the 2 things that ulcers in this region can do? Where do they often do it?
Perforate: bile & acids into intraperitoneal space
–>usu happens on the anterior portion
Bleed: a ton of blood can leave the gastroduodenal artery b/c close to the aorta
–>usu happens on the posterior portion
–>needs to be ligated to stop the bleeding
What is the area behind the stomach called?
the lesser sac
How long is the second portion of the stomach? What is it commonly referred to as? Is it intraperitoneal or retroperitoneal?
Retroperitoneal now!!
8-10 cm
C-loop
**the pancreas kind of snuggles up in there.
What important thing drains here?
This is where the pancreatic duct & common bile duct come together as the ampulla of Vater & drain.
What is another name for the ampulla of Vater?
hepatopancreatic ampulla
How long is the third portion of the duodenum? What is it also referred to as? What significant thing happens here? Intra or retroperitoneal?
5-8 cm in length
Retroperitoneal
Horizontal portion
**proceeds horizontally from right to left
**the SMV & SMA cross anterior to the duodenum @ the third portion.
How long is the fourth portion of the duodenum? Intra or retroperitoneal? Where does it begin & end?
2-3 cm
Retroperitoneal
Begins to the left of the SMV/SMA
Ends @ ligament of trietz (beginning of the jejunum)
What is the journey of the fourth portion of the duodenum? What is another name for it?
Ascending portion
It begins left of the SMV/SMA & has a short journey where it hikes superiorly & to the left. Then it takes a perilous dive after the ligament of trietz at which point it is the jejunum.
What is the blood supply to the duodenum very similar to? What are the 2 main arteries that are responsible?
very similar to the pancreas
- superior pancreaticoduodenal artery
- inferior pancreaticoduodenal artery
Starting w/ the abdominal aorta…& ending with the superior pancreaticoduodenal artery…describe the branching pathway.
Abdominal Aorta Celiac Trunk Common Hepatic Artery Gastroduodenal Artery Superior Pancreaticoduodenal Artery
Starting w/ the abdominal aorta…& ending with the inferior pancreaticoduodenal artery…describe the branching pathway.
Abdominal Aorta
Superior Mesenteric Artery
Inferior Pancreaticoduodenal Artery
Describe the venous drainage of the duodenum.
Most of the drainage of the duodenum goes into the superior mesenteric vein. This drains into the portal vein. It goes into portal circulation–>cycles thru the liver.
Describe the lymphatic drainage of the duodenum.
the lymph first drains into the pancreaticoduodenal lymph nodes. It then drains into the celiac nodes.
What’s the deal w/ a malrotation of the small bowel?
@ 7-8 weeks the intestine exits the fetus to become properly rotated and goes back in. This is where a 270 degree rotation forms the C loop of the duodenum. This is also when the duodenum tucks underneath the superior mesenteric vessels. When it doesn’t do this properly–>malrotation & problems.
What are the problems with malrotation?
the malrotation can make the mesentery very tight & easily turned about to strangle a blood vessel. This is called a mid gut volvulus. It can kill the bowel & cause short bowel syndrome.
What are the symptoms of malrotation & when do they usu show up?
could show up in a newborn, but not necessarily
bilious vomit (green)
This makes you think–>oh no! mid gut volvulus
What is a crus of the diaphragm? Plural–crura of the diaphragm?
tendinous structures that extend inferiorly into the diaphragm & attach to the vertebral column & create a tether for muscle contraction
What is the ligament of treitz really a continuation of?
the crus of the right diaphragm
What is the blood supply of the jejunum & ileum?
the SMA
The last chunk of the small intestine (jejunum & ileum) begins where & ends where? How long is the portion all together?
Begins @ ligament of Trietz
Ends @ ileocecal valve
6-7 meters
Which portion of the last chunk of small intestine (jejunum & ileum) is jejunum? What is the point of division?
The first 2/5 of this last chunk is jejunum. However, there is no structure that demarcates this.
What are important external differences b/w the jejunum & the ileum?
The jéjunum is thicker & more muscular than the ileum.
Generally…where is the jejunum found in the body? How about the ileum?
Jejunum: upper abdomen, more toward the left
Ileum: lower abdomen & pelvis, more toward the right
What is the internal difference b/w the jejunum & ileum?
The jéjunum has more well developed plicae circulares in the mucous membrane. This provides an absorptive surface.
Note: if a portion of the SI is removed…other portion can adapt & develop their plicae.
The jéjunum & ileum are suspended from what structure?
Mesentery
What does the mesentery carry w/i it?
blood vessels & lymphatics
If the mesentery is a skirt…what is at the waist? What is at the hem?
Waist: root of the mesentery–>emanates from the superior mesenteric vessels & fans out along the bowel…begins underneath the transverse colon
Hem: bowel
What is the border of the bowel called that is closest to the mesentery? The part of the bowel that is furthest from the mesentery?
Closest to the mesentery: mesenteric border
Furthest from the mesentery: anti-mesenteric border
When you are looking at whether or not you need to remove a section of the bowel…do you look at the mesenteric border or the anti-mesenteric border?
The anti-mesenteric border b/c that is furthest from the blood supply & shows the true health of the bowel. Remember: when you remove bowel–>there is still collateral flow that will keep the remaining bowel healthy.
Describe the blood supply to the jejunum & the ileum.
It begins @ the SMA, which gives off 15-18 branches, called jejunal & ileal intestinal arteries. Then these form loops called arcades (help w/ collateral flow).
Then it forms the straight arteries aka vasa recta.
The vasa recta enter the mesenteric side of the bowel.
Describe the venous drainage of the jejunum & ileum.
It mirrors the arterial supply. It even has arcade-like loops. It drains into the SMV & then into the portal vein.
Describe the lymphatic drainage of the small intestine.
Lacteals in the intestinal villi drain into the lymphatic plexus (which is a part of the mesentery). This plexus drains into the mesenteric lymph nodes.
Then they drain into the cisterna chyli and into the thoracic duct.
What are the 3 levels of mesenteric lymph nodes?
Those @ 3 locations:
Next to the intestine
Along arterial arcades
Along the SMA
What is the embryological roots of Meckel’s diverticulum?
It begins embryologically as the omphalomesenteric duct, which connects the distal small bowel to the umbilicus. It drains the intestinal contents.
What is Meckel’s diverticulum?
A 3-6 cm pouch in the ileum, w/i 2 feet of the ileocecal valve.
Can present as a persistent omphalomesenteric duct (somewhat common) OR w/ a fibrous cord connecting it to the umbilicus (very rare) OR just a little pouch (very common).
Does the Meckel’s diverticulum have a blood supply? If so, where?
Yes. On the anti-mesenteric border.
What are the 3 ways that you might find Meckel’s diverticulum?
Just randomly during a cadaver dissection or abdominal surgery…
B/c it caused an obstruction by telescoping during peristalsis (intussusception).
B/c it is bleeding from an ulceration to the gastric mucosa inside. Note: gastric mucosa isn’t always inside.
What is the rule of 2s with Meckel’s diverticulum?
2% of the population has it.
Only 2% of the people who have it are symptomatic.
The pouch is 2 inches long.
The diverticulum is found w/i the 2 feet proximally of the ileocecal valve.
Where does the large intestine begin & end? How long is it? What are its 2 functions?
Begins @ ileocecal valve Ends @ anus 1.5 meters long (5-6 feet) Absorbs water Stores feces
What is the order of sections of the LI from beginning to end?
Ileocecal valve Right colon/Ascending colon Hepatic Flexure Transverse Colon Splenic Flexure Left Colon/Descending Colon Sigmoid Colon Rectum Anus
What are the 3 distinguishing features of the LI?
Teniae Coli: 3 longitudinal muscle bands that run the full length of the colon
Haustra Coli: circular muscle that creates little pouch-looking things along the length of the colon…
Appendices Epiploicae: fatty appendages attached to the teniae coli.
Do the small intestines have longitudinal & circular muscle or only the LI?
Both have longitudinal & circular muscles. It is just much more obvious in the LI.
Does the SI have fat hanging off of it in portions?
NO. Only the LI as a sort of fat store.
Where does the cecum begin? What is it a part of? What is its blood supply?
Begins @ the ileocecal valve
A part of the ascending colon
sac-like structure
Blood supply: ileocolic artery (branch of SMA)
Where is the appendix found? What is its blood supply? What is its function?
found @ base of cecum & confluence of teniae coli.
Blood supply: ileocolic artery (branch of SMA)
Function: unknown, vestigial structure, is full of lymphoid tissue
T/F The appendix has its own mesentery.
True.
How does somebody get appendicitis?
When stool or something blocks the appendix & inflammation of the lymphoid tissue occurs.
What age group is appendicitis most often present in?
Age 10-19.
What is the classical presentation of appendicitis?
Starts off as periumbilical pain at first.
Nausea & Vomiting present.
Pain becomes localized & moves to the RLQ as it becomes more inflamed & peritoneal irritation occurs–> somatic neurons here.
Fever may occur later if it ruptures.
What are the 2 sources of the nerves of the small intestine?
Vagus nerve & splanchnic nerves
What does the parasympathetic nerve supply promote & what nerve is associated w/ this?
Promotes motility
Vagus nerve
Where does the sympathetic nerve supply come from?
Superior Mesenteric Ganglion
T9 & T10 segments
Visceral pain of the bowel is mediated by what? What does this feel like?
Mediated by thoracic nerve segments, not the vagus nerve…
More general, nonspecific pain.
Irritation of the actual peritoneum can be caused by what? What does this feel like? How is this information carried?
Blood, air, acid, infection
localized pain
somatic neurons
Where does the ascending/right colon begin? Where does it end? How long is it? Is it intra or retro?
It begins @ the cecum
It ends @ the hepatic flexure or right flexure
It is 12-20 cm long.
It is retroperitoneal.
What is the blood supply to the ascending colon?
The right colic artery, which is a branch of the SMA.
Where does the transverse colon begin? Where does it end? How long is it? Intra or retro?
Begins @ the hepatic flexure/right flexure
Ends @ the splenic flexure/left flexure
30-50 cm long
Intraperitoneal
What is the course of the transverse colon?
Intraperitoneal.
From the right side of the abdomen to the left…
What is the blood supply to the transverse colon?
Middle colic artery (branch off of the SMA)
Where does the descending colon/left colon begin & end? How long? Intra or retro?
Begins @ the splenic flexure/left flexure
Ends @ sigmoid colon/pelvic brim
15-20 cm long
Retroperitoneal
What is the blood supply of the descending colon?
Left colic artery (branch off of the IMA)
Where does the sigmoid colon begin & end? How long is it? Intra or retro?
Begins @ pelvic brim
Ends @ rectum
15-80 cm long
Intraperitoneal (in the LLQ)
What is a complication of the sigmoid colon being as long as 80 cm in some people?
In elderly patients who already struggle with their bowels…having a super long sigmoid colon can create a sigmoid volvulus where it turns in on itself…this can create terrible constipation.
What is the blood supply to the sigmoid colon?
2 or 3 sigmoid arteries off of the IMA
What are diverticuli?
pouches off of the colon in b/w teniae coli
usu occur in the sigmoid colon
What are 3 possible results when you have diverticuli?
Diverticulitis: infection of your diverticuli
Diverticular Hemorrhage: bleeding of the diverticuli
Perforation of the diverticuli: stuff spills out
Where does the rectum begin & end? How long is it? Intra or retro?
Begins @ S3 vertebrae (end of sigmoid)
Ends @ anus
12-15 cm
Retroperitoneal in the pelvis
Describe the blood supply to the rectum. Note: this is an area with collateral flow.
Superior Rectal Artery (branch off of IMA)
Middle & Inferior Rectal Arteries (branches of the internal iliacs)
What are 2 things that the rectum doesn’t have that the sigmoid colon does have?
Doesn’t have:
teniae coli
diverticuli (b/c of the support of the pelvic floor)
What is the function of the rectum?
to support & store feces before defecation.
What does the rectum have that the sigmoid colon doesn’t have?
Does have:
internal transverse rectal folds
**they help break up the feces
**they are continuations of the teniae
What is the lymphatic drainage of the cecum & appendix?
periappendiceal lymph node
to the
superior mesenteric lymph node
What is the lymphatic drainage of the ascending colon?
paracolic lymph node
to the
superior mesenteric lymph node
What is the lymphatic drainage of the transverse colon?
Superior mesenteric lymph node
What is the lymphatic drainage of the descending colon?
Inferior Mesenteric lymph node
What is it important to do during oncologic surgery of the colon?
Remove the mesentery which has the blood supply & lymph drainage…
this is the way that cancer spreads.
Blood vessels are often removed up to the IMA
What is the lymphatic drainage of the sigmoid colon?
Inferior Mesenteric Lymph node
What is the lymphatic drainage of the superior portion of the rectum?
pararectal lymph nodes
to the
inferior mesenteric lymph nodes
What is the lymphatic drainage of the inferior portion of the rectum?
internal iliac lymph nodes
What are the 2 innervations of the large intestine?
The colon is supplied by both the superior mesenteric plexus (the portion supplied by SMA)
& the inferior mesenteric plexus (portion supplied by IMA)
What is the innervation of the rectum?
the middle rectal plexus (from the inferior hypogastric plexus)
Where does the anus begin? How long is it?
begins @ the puborectalis muscle
2.5-5 cm or 1-2 inches long
What’s the deal with the anal sphincters?
Internal anal sphincter involuntary
External anal sphincter voluntary
What’s the change of tissue in the anus?
there is a transition from intestinal mucosa to anoderm (skin).
What is the innervation of the anus?
The external anal sphincter is innervated by the inferior rectal nerve.
What are distinguishing features of the superior portion of the anus?
mucosa similar to the rectum
folds called anal columns that allow for stretching for feces
What are distinguishing features of the inferior portion of the anus?
the anal columns seen in the superior portion end @ the anal valves…around this section is the pectinate line & the division b/w the superior & inferior
What are hemorrhoids?
dilations of the veins in the anal region
Describe the venous drainage of the anus.
The middle & inferior portions of the anus are drained by iliac veins…
The superior portion of the anus is drained by the superior rectal vein
What is the arterial supply for the superior portion of the anus?
Superior rectal artery
What is the arterial supply for the inferior portion of the anus?
inferior rectal artery
Internal hemorrhoids are dilations of what vein? External hemorrhoids are dilations of what vein?
Internal: superior rectal vein
External: inferior rectal vein
SMA & SMV cross over which part of the duodenum?
the 3rd portion
