Anatomy Abdomen Flashcards
Calot’s triangle borders
superior: inferior border of liver
medial: common hepatic duct
lateral: cystic duct
located at the porta hepatis of liver
Calot’s triangle contents
cystic artery, right hepatic artery, Lund’s lymph node
inguinal (Hesselbach) triangle borders
inferior: inguinal ligament
medial: lateral border of rectus abdominis muscle
lateral: inferior epigastric vessels
inguinal Hesselbach triangle relevance
no structures within it
demarcates area of weakness through which direct hernia occurs and enters inguinal canal
difference between direct and indirect inguinal hernias
DIRECT: protrudes through inguinal triangle, can exit through superficial inguinal ring, origin medial to inferior epigastric vessels
INDIRECT: protrudes through deep inguinal ring and exits through superficial ring, origin lateral to inferior epigastric vessels
both can reach scrotum
inferior epigastric vessels origin
external iliac artery and vein
subdivisions of peritoneal cavity and what divides them
lesser sac (omental bursa): posterior to stomach and lesser omentum --> connected to greater sac via epiploic foramen of Winslow greater sac: divided into supracolic and infracolic compartments by transverse mesocolon (mesentery of transverse colon) infracolic : divided into right and left infracolic spaces by mesentery of small intestine supracolic and infracolic compartments are connected by right and left paracolic gutters (between posterolateral abdominal wall and lateral aspect of ascending or descending colon)
location of epiploic foramen
posterior to hepatoduodenal ligament (free edge of lesser omentum)
supracolic compartment contents
stomach, liver, spleen
infracolic compartment contents
small intestine, ascending and descending colon
subphrenic recesses
potential spaces in supracolic compartment, between diaphragm and liver
right and left spaces separated by falciform ligament of liver
subphrenic abscesses
accumulation of pus in right or left subphrenic spaces, more common on right due to high frequency of appendicitis or ruptured duodenal ulcers
(pus reaches up to right subphrenic space through right paracolic gutter)
differences between peritoneal cavity in pelvis of males vs females
males: rectovesical pouch
females: rectouterine pouch (Douglas) + vesicouterine pouch
characteristic of lumbar vertbebrae
triangular vertebral foramen
largest in size to support weight
length of esophagus
25 cm
esophagus origin and end levels
cricoid cartilage inferior border C6 - cardiac orifice of stomach T11
esophageal hiatus level
T10
type of epithelium of esophageal muscosa
stratified squamous
upper esophageal sphincter made of
cricopharyngeus muscle, constricts to prevent air into esophagus
lower esophageal sphincter made of
no muscles, at gastro-esophageal junction to the left of T11, “physiological” sphincter (made of acute angle and compression of walls due to high intra abdominal pressure)
4 physiological constrictions of esophagus
ABCD Aortic arch Bronchus (left) Cricoid cartilage Diaphragmatic hiatus
esophagus blood supply
thoracic: thoracic aorta + inferior thyroid artery
abdominal: left gastric artery + left inferior phrenic arterty
barret’s esophagus
long-standing GERD causes metaplasia of lower epithelium - squamous to columnar (like stomach)
esophageal cancer types
squamous cell carcinoma, most common
adenocarcinoma, from Barret’s esophagus, only in inferior third of esophagus
present with dysphagia and weight loss
transpyloric plane level
L1, demarcated by pyloric sphincter
greater curvature of stomach start to end
starts at cardiac notch to reach pyloric antrum - lateral border of stomach
lesser curvature of stomach start to end
medial surface, starts at cardia to reach angular notch (junction between body and pylorus)
attached to hepatogastric ligament
Lesser omentum attachments
from stomach and duodenum to liver
Greater omentum attachments
from stomach to transverse colon
Stomach blood supply
anastomoses of right and left gastric arteries along lesser curvature
Anastomoses of right and left gastro omental arteries along greater curvature
sliding vs rolling hiatal hernia
sliding: lower esophageal sphincter slides up superiorly with part of cardia
rolling: sphincter stays in place while part of cardia slides up next to it
epiploic foramen contents
hepatoduodenal and hepatogastric ligaments
parts of duodenum
D1 superior: hepatoduodenal ligament - common for duodenal ulcers
D2 descending: curves around pancreatic head - posterior to transverse colon - major duodenal papilla (opening of ampulla of Vater)
D3 inferior: crosses over aorta and ICV but posterior to SMA and vein - inferior to pancreas
D4 ascending: duodejejunal flexure - at junction, suspensory muscle of duodenum (ligament of Treitz)
duodenal ulcer causes and complications
H. pylori, chronic NSAID
perforation can cause peritonitis or erosion of gastroduodenal artery –> hypovolemic shock
differences between jejunum and ileum
jejunum has longer vasa recta and less arcades (arterial loops) - red color
ileum - pink color, short vasa recta, more arcades
duodenum blood supply
proximal to duodenal papilla D2: gastroduodenal artery
distal to D2: inferior pancreaticoduodenal artery
transition marks change from foregut to midgut
jejunoileum blood supply
SMA
ileocecal valve importance in large bowel obstruction
if competent (no backflow into ileum): closed loop obstruction (2 points obstructed) - emergency, perforation if incompetent (backflow allowed): less emergent, decompresses the cecum
cecum blood supply
ileocolic artery (from SMA)
most common position of appendix
retrocecal
cecum and appendix embryologic origin
midgut
appendix blood supply
appendicular artery (from ileocolic or right colic artery)
right colic flexure at which organ
liver
left colic flexure at which organ
spleen
colon length
150 cm
large intestine features to distinguish it from small intestine
- omental appendices (small pouches of peritoneum filled with fat on surface)
- teniae coli (3 longitudinal strips of muscle)
- haustra
- wider diameter
- -> these features end at rectosigmoid junction
embryological origin of colon
midgut: ascending + 2/3 transverse
hindgut: 1/3 transverse + descending + sigmoid
colon blood supply
right colic - ascending
middle colic - transverse
left colic - descending
sigmoid arteries - sigmoid (from left colic)
which part of rectum relaxes to accumulate and store feces
ampulla - continuous with anal canal
rectum blood supply
superior rectal artery - terminal continuation of IMA
middle rectal artery - internal iliac artery
inferior rectal artery - internal pudendal artery
what is palpated with DRE
anterior wall of rectum is in direct contact with prostate and seminal vesicles / cervix
anal canal sphincters
internal: surrounds upper 2/3, involuntary smooth muscle
external: surrounds lower 2/3, voluntary muscle, continuous with puborectalis muscle
what is anorectal ring
fusion of internal and external anal sphincters and puborectalis muscle, at junction of rectum and anal canal
what is pectinate line
“dentate line”
divides upper part of anal canal made of columnar epithelium from lower part made of stratified squamous epithelium
anal canal blood supply
above pectinate line: superior rectal artery
below pectinate line: inferior rectal artery
–> anastomosing branches from middle rectal artery supply both
location of liver
right hypochondrium
where is the bare area of the liver
posterior aspect of diaphragmatic surface, direct contact with diaphragm
not covered in any visceral peritoneum
at which level does the aorta bifurcate and into what
L4
right and left common iliac arteries
level of aortic hiatus in diaphragm
T12
normal aorta diameter
less than 3 cm
branches of abdominal aorta
- inferior phrenic arteries
- celiac trunk at T12
- SMA at L1
- middle suprarenal arteries at L1 (adrenals)
- renal arteries between L1 and L2
- gonadal arteries at L2
- IMA at L3
- lumbar arteries from L1 to L4
- median sacral artery at L4 (coccyx, sacrum, lumbar vertebrae)
branches of celiac trunk
- left gastric
- splenic
- common hepatic
left gastric artery branches
esophageal branches
continues to supply lesser curvature and anastomose with right gastric artery
splenic artery pathway + branches
posterior to stomach, along superior margin of pancreas, through splenorenal ligament
branches:
- left gastroepiploic (greater curvature, anastomoses with right)
- short gastrics (5-7 small branches supply fundus)
- pancreatic branches (body and tail of pancreas)
terminates into 5 branches that supply spleen
has tortuous appearance
common hepatic artery branches
- sole arterial supply of liver*
- proper hepatic
- gastroduodenal
proper hepatic:
- right gastric
- right and left hepatic (right hepatic give cystic)
gastroduodenal:
- right gastroepiploic
- superior pancreaticoduodenal (inferior from SMA)
which organ receives blood from the 3 branches of the celiac trunk
stomach
celiac trunk compression syndrome
median arcuate ligament (fibrous anchor of diaphragm that forms aortic hiatus) lies anterior to celiac trunk instead of superior –> compressing it
position of SMA related to pancreas
neck of pancreas is anterior to it
uncinate process is posterior to it along with inferior duodenum
SMA branches
- inferior pancreaticoduodenal (pancreatic head, uncinate process, duodenum)
- jejunal and ileal
- right colic
- middle colic
- ileocolic (gives appendicular)
SMA and IMA supply structures of which embryonic origin
SMA: midgut
IMA: hindgut (distal 1/3 transverse till rectum)
IMA level and location
L3
inferior border of duodenum, 3-4 cm above bifurcation into common iliacs
IMA branches
- left colic (distal 1/3 of transverse, descending colon)
- sigmoid arteries
- superior rectal
they cross OVER left ureter
watershed areas
splenic flexure, rectoigmoid junction
–> blood supply from 2 large arteries - more sensitive to systemic hypoperfusion
falciform ligament
attaches anterior surface of liver to anterior abdominal wall
contains ligamentum teres (remnant of umbilical vein)
coronary ligament
attaches superior surface of liver to diaphragm
has anterior and posterior folds which unite at each side to make right and left triangular ligaments
demarcates the bare area of liver
right and left triangular ligaments
made from union of anterior and posterior coronary ligaments at apex of liver, attach it to diaphragm
lesser omentum attachment to liver
attaches liver to lesser curvature of stomach and D1
consists of hepatoduodenal ligament and hepatogastric ligament
what surrounds the portal triad
hepatoduodenal ligament
what are the hepatic recesses
- subphrenic space: between diaphragm and liver, divided into right and left by falciform ligament
- subhepatic: between liver and transverse mesocolon
- morison’s pouch: between liver and right kidney, deepest part of peritoneal cavity when supine (for bedridden patients)
anatomical structure of liver
left lobe, right (larger) lobe
2 accessory lobes arise from right lobe - on visceral surface: caudate and quadrate
where is caudate lobe
upper part of visceral surface
between IVC and fossa made by ligamentum venosum (remnant of fetal ductus venosus)
where is quadrate lobe
lower part of visceral surface
between gallbladder and fossa made by ligamentum teres
what is the liver covered with
Glisson’s capsule (fibrous layer)
distension of capsule causes sharp pain
where is the porta hepatis
contents
visceral surface, between caudate and quadrate - it runs in the hepatoduodenal ligament
all vessels, nerves (vagus), ducts except hepatic veins
mainly: hepatic artery, portal vein, common hepatic duct
liver blood supply
dual supply:
hepatic artery proper 25% - non-parenchymal part
hepatic portal vein 75% - parenchyma, partially deoxygenated blood with nutrients from small intestine, for detoxification
venous drainage through many small hepatic veins which drain into IVC
gallbladder storage capacity
30-50 mL
what is Hartmann’s pouch
mucosal fold in neck of gallbladder, most common location for gallstone impaction, causing cholestasis
biliary tree pathway
bile made in liver, travels through right and left hepatic ducts which combine to make common hepatic duct
CHD joins cystic duct to form common bile duct which travels posterior to D1 and pancreatic head to reach pancreatic duct and form ampulla of Vater (hepatopancreatic ampulla) which opens in D2 via major duodenal papilla and is regulated by sphincter of Oddi
what stimulates contraction of gallbladder
parasympathetic stimulation causes contraction of GB and relaxation of sphincter of Oddi
+ cholecystokinin (gustatory response)
charcot’s triad
for cholangitis
fever, jaundice, RUQ pain
pancreas level and position in peritoneal cavity
transpyloric plane L1
retroperitoneal EXCEPT its tail
pancreas and vessels relationship
- aorta and IVC pass posterior to head
- SMA passes behind neck but anterior to uncinate
- splenic and superior mesenteric vein unite behind neck of pancreas to form portal vein
- splenic artery traverses superior border of pancreas
pancreatic tail attached to spleen by what
splenorenal ligament with the splenic vessels
pancreas blood supply
pancreatic branches from splenic artery
pancreatic head also from superior and inferior pancreaticoduodenal arteries (from gastroduodenal -celiac- and SMA)
pancreatitis causes
GET SMASHED Gall stones Ethanol Trauma Steroids Mumps Autoimmune Scorpion sting HyperCa, hypertriglycerides, hyperparathyroidism ERCP Drugs (sodium valproate, azathioprine and sulphonamides)
relevance of vascular segments of spleen
arterial branches from splenic artery do not anastomose with each other, enabling subtotal splenectomy without affecting other segments
splenectomy vaccine
Pneumococcal, meningococcal, and Haemophilus influenzae (Hib)
2 weeks before or after surgery
shape of adrenal glands
right: pyramidal
left: semi lunar
adrenal gland layers
outer capsule, cortex, medulla
adrenal gland cortex function
from mesoderm
zona glomerulosa - aldosterone (mineralocorticosteroids)
zona fasciculata - cortisol (corticosteroids)
zona reticularis - DHES (androgens)
adrenal gland medulla function
from ectodermal neural crest cells
contains chromaffin cells, secrete adrenaline (catecholamines)
pheochromocytoma
tumor in adrenal medulla
secretes adrenaline and noradrenaline
phenoxybenzamine - adrenaline antagonist
what encloses the kidneys and adrenal glands
renal fascia “Gerota’s fascia”
avascular plane of kidney
line of Brodel
along lateral slightly posterior border of kidney, important access for open and endoscopic surgeries, minimizes risk of damage to major arteries
lymphatic drainage of kidneys
para-aortic nodes
segmental vascular supply of kidneys relevance
like spleen, branches do not anastomose
can perform partial nephrectomies
NB: if one branch is obstructed, its part of kidney will die because no other supply
pelvic kidney location
kidney that failed to ascend
level of common iliac artery
root of mesentery function and pathway
mesentery: anchors small and large intestine to posterior abdominal wall, provides conduit for vessels
root: bare area, attaches mesentery to posterior abdominal wall
oblique orientation: left side of L2 till right sacroiliac junction
which part of mesentery is most mobile
transverse mesocolon
most common area of volvulus
sigmoid
retroperitoneal organs
SAD PUCKER Suprarenal glands Aorta + IVC Duodenum (except 2cm of D1 "cap") Pancreas (except tail) Ureters Colon (ascending + descending) Kidneys Esophagus Rectum
mesentery vs omentum
both are double layers of visceral peritoneum
omentum comes from stomach mainly and proximal part of duodenum
mesentery for rest of organs (named according to organ its covering, “the mesentery” for small intestine)
lesser omentum consists of
hepatogastric ligament and hepatoduodenal ligament
embryological origin of organs and referred pain
foregut referred to epigastric region:
esophagus, stomach, pancreas, liver, gallbladder, duodenum (proximal to entrance of CBD)
midgut referred to umbilical region:
duodenum to proximal 2/3 of transverse colon
hindgut referred to pubic region:
distal 1/3 of transverse to upper part of anal canal
abdominal muscles
3 flat: external oblique, internal oblique, transversus abdominis
2 vertical: rectus abdominis, pyramidalis
linea alba
aponeuroses of all 3 flat muscles join in midline of abdomen
from xiphoid to pubic symphysis
rectus abdominis structure
split in half by linea alba
lateral borders create linea semilunaris
tendinous intersections are fibrous strips that intersect the muscle horizontally –> intersections + linea alba: 6 pack
pyramidalis location
anterior to rectus abdominis
triangle shape, base at pubis bone, apex at linea alba
rectus sheath
aponeuroses of 3 flat muscles covering rectus abdominis
anterior wall: external oblique + 1/2 internal oblique
posterior wall: 1/2 internal oblique + transversus abdominis
arcuate line
midway between umbilicus and pubic symphysis
below arcuate, rectus sheath has only anterior wall with the 3 aponeuroses of the 3 muscles
no more posterior wall, rectus abdominis in direct contact with transversalis fascia
superficial fascia composition based on location
above umbilicus: single sheet
below umbilicus: Camper’s fascia and Scarpa’s fascia - superficial vessels and nerves run between them
inguinal canal function
allows structures to pass from abdominal cavity to external genitalia
indirect hernia cause
failure of processus vaginalis to regress
sac herniates in canal based on amount of processus vaginalis still present
what is gubernaculum
fibrous cord which attaches to gonads, guides them in their descent, then attaches them to future scrotum or labia
what does gubernaculum become
males: scrotal ligament
females: ovarian ligament + round ligament of uterus
mid-inguinal point vs midpoint of inguinal ligament
mid inguinal: between ASIS and pubic symphysis - femoral pulse
midpoint of inguinal ligament: between ASIS and pubic tubercle - above this point is the opening of inguinal canal
inguinal canal walls
anterior: external oblique aponeurosis
posterior: transversalis fascia
roof: internal oblique, transversus abdominis, transversalis fascia
floor: inguinal ligament, lacunar ligament
inguinal ligament made of
external oblique aponeurosis
deep/internal inguinal ring made of
transversalis fascia
above midpoint of ligament
superficial/external inguinal ring made of
external oblique aponeurosis
inguinal canal contents
spermatic cord (male), round ligament (female), ilioinguinal nerve, genital branch of genitofemoral nerve
ilioinguinal nerve function
sensory innervation of genitalia
genital branch of genitofemoral nerve function
supplies cremaster muscle + anterior scrotal skin
OR skin of mons pubis + labia majora
direct hernia cause
weakness in abdominal muscles
What ligament attaches to lesser curvature of stomach
hepatogastric ligament
