Lopez: Small Intestine, Colon, Anus Flashcards
foregut supplied by what artery
celiac trunk
foregut consists of what structures
(liver, gallbladder, stomach, spleen, pancreas, proximal duodenum, esophagus)
midgut consists of what structures
(distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal 2/3 of transverse colon)
midgut supplied by what artery
superior mesenteric artery
hindgut consists of what structures
distal 1/3rd of transverse colon, descending colon, sigmoid colon, rectum, and upper part of anal canal
hindgut supplied by what artery
inferior mesenteric artery
lymphatic drainage of fore, mid, and hindgut
foregut: celiac nodes
midgut: superior mesenteric nodes
hindgut: inferior mesenteric nodes
4 steps of midgut embryology
herniation of midgut loop
rotation of midgut loop
retraction of intestinal loops
fixation of intestines
herniation of midgut loop happens through ____ duct
omphaloenteric duct
____ limb grows rapidly and forms small intestinal loops
cranial limb
_____ limb develops the cecum and appendix
caudal limb
while in umbilical cord, how much does the midgut loop rotate
90 degrees
how much does the large intestine turn (retraction of intestinal loops)
180 degrees
around 10-12 weeks, this rotation is crucial for normal position of organs in abdominal cavity
270 degree rotation (fixation of intestines)
the ____ and ____ colon become fixated in retroperitoneum
ascending and descending
congenital anomaly that occurs due to an abnormal rotation and fixation of intestines during fetal development
midgut malrotation
small intestine being on the right side; doesn’t rotate fully
incomplete rotation
abnormal fibrous bands leading to obstruction
Ladd’s bands
abnormal positioning and fixation of midgut leaves it prone to ____
volvulus
persistence of the herniation of abdominal contents into proximal part of umbilical cord (herniation of intestines into cord)
congenital omphalocele
congenital abdominal wall defect characterized by the protrusion of abdominal contents through a defect in abdominal wall
Gastroschisis
defect in lateral body folding (mainly on R side) and leads to abdominal contents failing to return to abdominal cavity
Gastroschisis
congenital anomaly resulting from incomplete obliteration of the omphalomesenteric duct (vitelline duct)
Meckel’s Diverticulum
anomaly that leaves a connection from ileum to umbilicus
Meckel’s Diverticulum
has presence of ectopic tissue (gastric or pancreatic) due to incomplete obliteration of vitelline duct
Meckel’s Diverticulum
if gastric tissue surrounds this and gets inside can erode wall due to low pH and perforate
Meckel’s Diverticulum
painless rectal bleeding
abdominal pain
intestinal obstruction
perforation
Meckel’s Diverticulum
2 year-old male with history of constipation presented with one episode of painless hematochezia that occurred 1 hour prior to arrival. He had a benign abdominal exam. POCUS revealed a focal fluid collection in the RLQ with a bowel wall appearance containing a hyperechoic focus
Meckel’s Diverticulum
congenital disorder characterized by failure of neural crest cell migration
Hirschsprung Disease
abscence of ganglion cells in the myenteric and submucosal plexuses in distal colon
Hirschsprung disease
This aganglionosis results in a lack of peristalsis in the affected segment and of the bowel is unable to relax and remains in a contracted state
Hirschsprung disease
megacolon
Hirschsprung disease
RET mutation; lack of ICCs
Hirschsprung disease
clinical features of this include delayed passage of meconium w/in first 48 hours
Hirschsprung disease
progressive abdominal distension
bilious vomiting
failure to thrive
enterocolitis
Hirschsprung disease
megacolon
older individuals
chronic constipation
parkinson’s
surgeries
Volvulus
loop of intestine twists around itself leading to mechanical obstruction
Volvulus
twisting–poor blood supply—edema—blockage—perforation
volvulus progression
abdominal pain
abdominal distension
N/V
constipation
shock
Volvulus
high fiber diet makes this worse
volvulus
“whirlpool sign” on US
volvulus
“coffee bean shape”
sigmoid volvulus
mostly in kids
prior viral infections
congenital anomalies
Intussusception
condition in which part of the intestine telescopes into itself
Intussusception
Intussusception
occurs when a segment of the intestine telescopes into an adjacent segment, leading to obstruction and potential ischemia
intussusception
typically involves the ileum telescoping into the colon at ileocecal junction
intussusception
intermittent abdominal pain
vomiting
“currant jelly” stools
palpable abdominal mass
intussusception
currant jelly stools
sausage shaped palpable mass in RUQ or epigastrium
intussusception
currant jelly stools
target configuration on US
intussusception
lies at level of L1-L3; has segments
duodenum
D1
D2
D3
D4
D1: superior
D2: descending
D3: horizontal
D4: ascending
superior part of duodenum at what vertebral level
L1
horizontal part of duodenum at what vertebral layer
L3
main arteries supplying top part of duodenum
gastroduodenal
anterior superior + posterior superior pancreaticoduodenal
main arteries supplying bottom part of duodenum
posterior inferior + anterior inferior pancreaticoduodenal arteries
layers of duodenum
mucosa
submucosa
muscularis externa
adventitia
this layer of duodenal mucosa consists of enterocytes, goblet cells, and crypts
epithelial
this layer of duodenum has brunner glands
submucosa
duodenum
small intestine has ___% enterocytes and ____% goblet cells
80% enterocytes
20% goblet cells
tumors that grow out of lymphoid tissue
GALT
these glands help change acidic stomach pH to more neutral pH
brunner glands
feathery
duodenum
ileum
connivent valves
part of small intestine located on L side
jejunum
part of small intestine located in lower abdomen
ileum
connivent valves of duodenum and jejunum aid in what
peristaltic movements
blue: ascending colon
white: transverse colon
green: descending colon
orange: cecum
yellow: rectum
vasa recta longer in _____ than in the ileum
jejunum
this artery runs along the whole colon
marginal a.
branches of SMA
iliocolic
right colic
middle colic
marginal
branches of IMA
left colic
sigmoidal
superior rectal
marginal
branches of iliocolic artery off SMA
illeal branch
colic branch
appendicular branch
branches of L colic artery off of IMA
ascending branch
descending branch
arteries that supply rectum
superior rectal
middle rectal
inferior rectal
this pain starts around umbilicus (dull) and travels to RLQ as sharp pain
appendicitis
when there is sharp pain in the abdomen, not referred pain, why?
irritation of peritoneum
rebound tenderness means what
peritoneum is involved
periumbilical visceral pain runs through what nerve to CNS
lesser splanchnic n. (T10-T11)
when peritoneum is inflamed, somatic pain runs through what to CNS
least splanchnic n
lumbar sacral
(T11-L1)
contains valves of Kerckring
mucosa
submucosa
muscularis externa
serosa
Jejunum
no glands seen in this submucosa
jejunum
this layer of jejunum contains immune cells
lamina propria
this layer of jejunum mucosa contains enterocytes w/ goblet cells
epithelial
jejunum
filled with army of lymphoid tissue (GALT); many tumors from this tissue that lines the GI tract arise at the ______
Ileum
this layer of Ileum contains Peyer’s Patches (a lot of lymphocytes–bc ileum is close to colon that has a lot of bacteria)
lamina propria
Peyer’s Patches (of Ileum)
Ileum
not as much villi here (absorption happens mainly in small intestine)
Colon
culprit of diveriticuli formations
colon
huge amount of goblet cells
colon
colon
colon (w/ diverticuli)
___% enterocytes in colon
___% goblet cells in colon
20% enterocytes in colon
80% goblet cells in colon
rectum part of recto-anal junction
anus part of recto-anal junction
anal transition zone
pectinate line
external sphincter composed of what muscle
skeletal
apocrine and sebaceous glands of recto-anal junction
68 yr old pt w/ post prandial pain
hx of A-fib
hasn’t taken warfarin in a few days
acute mesenteric ischemia
if you lose SMA on CT, means a clot (necrosis)
acute mesenteric ischemia
what part of GI tract would be removed in acute mesenteric ischemia where SMA was occluded
all part of proximal small bowel
risk factors include:
A-Fib
advanced age
atherosclerosis
acute mesenteric ischemia
embolic occlusion
thrombotic occlusion
non-occlusive mesenteric ischemia
mesenteric venous thrombosis
pathophys of acute mesenteric ischemia
severe abdominal pain
N/V
diarrhea or bloody stools
acute mesenteric ischemia