Small and large intestines Flashcards
foregut
oropharynx to D2
coeliac trunk
mid gut
D2 to distal 1/3 transverse colon
SMA
hindgut
distal 1/3 transverse to anus
IMA
structure of bowel
interior outwards
- mucosa
-muscularis mucosa
- submucosa
- muscle
- serosa
duodenum
c shaped around ehad of pancreas
4 parts
superior D1 - pylorus to right side of L1
intraperitoneal
posterior relations: CBD, PV, gastroduodenal
Descedning D2 - runs inferiorly L1-L2
CBD and pancreatic ducts enter
Inferior
longest
passes infront of IVC and aorta to the left side of L3
Asending
upwards to L2
termiates at DJ flexure - supported by ligamen f triietz (peritoneal fold)
blood supply of duodenum
coeliac and sma
coeliac - superior anterior and inferior pancreaticoduodenal areries
sma - inferior anterior and inferior pancreaticoduodenal arteries
posterior duodenal ulcer
can be compliacted by erosion of the gastroduodenal artery causing haemorrhage
plicae circulares
mucosal folds in the jejunum and ileum
blood supply of jejunum an ileum
sma
hehunal and ileal arteries - form arterial arcades which form the straight vasarecta that pass into the intestine
differences between ileum and jejunum
ileum is longer (3/5)
jejunum has a thicker wall and large diameter
jejunum is dark red and ileum id pale pink
jejunum has less prominent arterial arcades and longer vasa recta
ileum has a thicker mesentry and peyer’s patches
features of large bowel
larger diameter
appendices epiploicae
taenia coli (three bands of longitudinal muscle)
haustra (sacculation caused by contraction of taenia)
meckel’s
congenital remnant of vitelline duct occuring in 2% of population
caecum
intraperitoneal
continuation of ileum
normally in RIF
enters at an oblique angle so has 2 ileal folds that act as a sphincter
blood supply caecum
anterior and posterior caecal arteries from ileocolic branch of SMA
where is bowel perf most likely to occur and why
caecum, largest diameter (7-9cm)
most likely site of obstruction and why
sigmoid, narrowest
position of appendix
posterior medial wall of caecum
suspended from terminal ileum by mesoappendix which contains the appendicular vessels
position is highly variable
- most commonly retrocaecal
can be pelvic, subcaecal or preileal
position of the base is consistent on the caecum where the three bands of taenia converge
blood supply appendix
appendicular artery from ileocolic branches of sma
colon intra vs retroperitoneal
ascending and descending colons are retroperitoneal
transverse and sigmoid are intraperionteal becayse thay have mesentry
symptoms of LBO
absolute constipation
vomiting
distention
colicky pain
common causes of LBO
tunour
hernia
diverticular disease
branches of SMA supplying colon
colic branch of ileocolic
right colic
middle colic
ima branches colon
left colic
sigmoid arteries
marginal artery of drummond
connects SMA and IMA
watershed area colon
splenic felxure
taenia coli in rectum
form a continuous layer of smooth muscle over the rectum
peritoneal coverings of rectum
upper 1/3 - extraperitoneal posteriorly
middle third - extraperitoneal posterior and lateral
lower 1/3 - completely extraperioneal
relations to rectum
posterior - sacrum, coccyx, sacral nerves
anterior - pouch of douglas, small intestine, bladder, prostate, vagina, uterus
lateral - levator ani
pouch of douglas
space between rectum and bladder or uterus
blood supply rectum
superior rectal from ima
internal ilac
middle rectal
inferior rectal
Anal canal
boundary between endoderm and ectoderm
upper 1/2
- columnar epithelium
- superior rectal vessels
- drains to lumbar nodes
lower 1/2
- squamous epithelium
- middle and inferior rectal vessels
- drains to inguinal nodes
lymph drainage
along mesentr to nodes near the origin of coeliac, sma and ima. then superiorly throigh cisterna chyli
