GI Anatomy Flashcards
what is the basic structure of the GI tract
mucosa
submucosa
muscularis externa
serosa
what is the GI tract
oesophagus to anus
describe the mucosa of the GI tract
- epithelium
- lamina propria
- muscularis mucosa
describe the epithelium of the GI tract
- includes exocrine cells from invaginated pits secreting digestive products and mucus
- increases SA for absorption and secretion
- covered in microvilli forming brush border
describe the lamina propria of the mucosa of the GI tract
= connective tissue
folded to increase SA
contains small nerves/blood vessels/lymphatics
describe the muscularis mucosa of the GI tract
thin layer of smooth muscle
describe the submucosa of the GI tract
layer of connective tissue containing network of nerves/blood/lymph which pierce layers above and below
describe the muscularis externa of the GI tract
- circular muscle = thick = narrow tube
- myenteric nerve plexus
- longitudinal muscle = thinner = shorten tube
describe the serosa of the GI tract
thin layer of connective tissue continuous with parietal peritoneum
- epithelium
- areolar tissue
where is Meissner’s plexus located
mainly within submucosa
where is auerbachs plexus located
between mucle layers
where is the upper extent of the abdominal cavity
anterior = under surface of diaphragm at 5th intercostal margin
name the 9 regions of the abdominal wall
R hyperchondrium - epigastric - L hyperchondrium
R flank - umbilical - L flank
R iliac fossa - suprapubic/hypogastric
what is the transpyloric plan of addison
halfway between suprasternal notch and superior border of symphysis pubis at level of L1
what is the subcostal plane
lowest point of costal margin at L2 level = origin of superior mesenteric artery
what is McBurney’s point
2/3 along line joining umbilicus to anterior superior iliac spine = base of appendix
what is the intertubular plane
line joining tubercles of iliac crest = L4 = bifurcation of aorta
what is the intercristal plan
line along back between highest points of pelvis = between L4 and L5 = lumbar puncture
what are the 2 layers of superficial fascia on the abdominal wall
camper’s fascia = fatty layer
scarpa’s fascia = membranous
name the 3 flat muscles of the abdomen
- external oblique
- internal oblique
- transverse abdominus
what is aponeurosis
all flat muscles form this flat broad tendon which covers the vertical rectus abdominis muscle
what is the linea alba
apaneurosis of flat muscles become entwined in midline = forms linea alba = xiphoid process - pubic symphysis
where does external oblique attach and inser
originates from 5 - 12 ribs inserts to iliac crest and pubic tubercle
what is the function of external oblique
contralateral rotation of torso
what innervates the external obliques
thoracoabdominal nerves T7-T11 and subcostal nerve T12
where does internal oblique attach and insert
originates from inguinal ligament/iliac crest and insert into 10 - 12 ribs
what is the function of internal oblique
contraction and rotation
what innervates the internal oblique
thoracoabdominal nerve T7-T11 and subcostal nerve T12
where does transversus abdominis attach and insert
originates from inguinal ligament/costal cartilages 7-12/iliac crest and insert into conjoint tendon/xiphoid process/linea alba/pubic crest
what is the function of transversus abdominis
compression of abdominal contents
what innervated transverse abdominis
thoracoabdominal nerves T7-T11/subcostal nerve T12
name the 2 vertical muscles of the abdomen
- rectus abdominis
2. pyramidalis
what is the rectus abdominis
long/paired muscle split by linea alba = lateral borders make linea semilunaris
what creates the appearance of a six pack
rectus abdominis is intersected by fibrous strips = tendinous intersections + linea alba = 6 pack
where does rectus abdominis attach and insert
originate from pubic crest and insert into xiphoid process at costal cartilages of ribs 5 - 7
what is the function of rectus abdominis
compressing abdomen/stabilising pelvis/depresses ribs
what innervates the rectus abdominis
thoracoabdominal nerves T7 - T11
what is pyramidalis muscle
small triangular sitting superior to the pubic bone = tenses linea alba = T12 subcostal nerve
what is the rectus sheath
formed by aponeuroses of 3 flat muscles = encloses rectus abdominis and pyramidalis muscles
what is the anterior wall of the rectus sheath formed of
aponeuroses of external oblique and half of internal oblique
what is the posterior wall of the rectus sheath formed of
aponeuroses of half internal oblique and transverse abdominis
where is there no posterior wall of rectus sheath
midline between umbilicus and pubic symphysis = all aponeuroses move to anterior wall = direct contact with transversalis fascia
what is peritoneal fluid
in peritoneal cavity = water/electrolytes/leukocytes/antibodies
describe intraperitoneal organs
enveloped by visceral peritoneum both anteriorly and posteriorly
describe retroperitoneal organs
covered in parietal peritoneum only covering anterior surface
what is parietal peritoneum
lines internal surface of abdopelvic wall
what is visceral peritoneum
invaginates to cover majority of abdominal viscera
what is a mesentary
double layer of visceral peritoneum connecting intraperitoneal organs to posterior abdominal wall
what is omentum
sheets of visceral peritoneum that extend from stomach and proximal duodenum to other organs
what is the greater omentum
4 layers of visceral peritoneum descending from greater curvature of stomach/prox duodenum then folds back up and attaches to anterior surface transverse colon
what is lesser omentum
double layer visceral peritoneum from lesser curvature of stomach/prox duodenum to liver
what are the 2 parts of the lesser omentum
- hepatogastric ligament = connect liver to stomach
2. hepatoduodenal ligament
what is the peritoneal ligament
double fold of peritoneum connects viscera together/to abdo wall
what do the omentum contain
fat/blood vessels/lymphatics/nerves
the lesser sac is also known as
the omental bursa
what is the epiploic foramen of winslow
an opening in the omental bursa that connects the omental bursa with the greater sac
where is the stomach located
upper part of abdomen from left costal margin into epigastric and umbilical region
what are the 2 openings of the stomach
cardiac and pyloric orifices
at what level is the inferior oesophageal sphincter
T11 = not under voluntary control
what is the blood supply of the stomach
branch of coeliac trunk
greater curvature = gastro-epiploic artery
lesser curvature = gastric artery
where do the right and left gastric veins drain
hepatic portal vein
what innervates the stomach
= autonomic
parasympathetic = for peristalsis = from vagus nerve
sympathetic = from T6-T9 to coeliac plexus via greater splanchnic nerve
at what level does the coeliac trunk branch off the aorta
T12
describe the superior duodenum
L1
connected to liver by hepatoduodenal ligament
intraperitoneal and retroperitoneal
lie in front of gastroduodenal arteries
describe the descending duodenum
L1-L3
curves inferiorly around head of pancreas
marked by internal major duodenal papilla
describe the inferior duodenum
L3
crosses over IVC and aorta
posterior to superior mesenteric artery and vein
describe the ascending duodenum
L3-L2
sharp turn = duodenojejunal flexure
the epiploic foramen is also known as
foramen of Winslow
mneumonic for retroperitoneal organs
SAD PUCKER
describe the mucosa of the duodenum
D1 = smooth, all else = plicae circularis
what part of the pancreas is intraperitoneal
the tail
what is the sphincter of Oddi
muscular valve controlling secretion into the duodenum from the pancreas
what is the ampulla of Vater
union of pancreatic duct and common bile duct = opens into duodenum via major duodenal papilla
what is the blood supply of the pancreas
- pancreatic branches of splenic artery = coeliac trunk
- sup/inf pancreaticoduodenal arteties = gastroduodenal
- superior mesenteric arteries
blood supply of the foregut is
coealiac trunk
what does the foregut consist of
abdominal oesophagus to ampulla of vater
what does the midgut consist of
inferior duodenum to 2/3rds transverse colon
blood supply of the midgut is
superior mesenteric artery
nerve supply of the foregut is
greater splanchnic nerve T5-T9
nerve supply of the midgut is
lesser splanchnic nerve T10-T11
what does the hindgut consist of
distal 1/3rd transverse colon to the rectum
blood supply of the hindgut is
inferior mesenteric artery
nerve supply of the hindgut is
least splanchnic nerve T12
what are the branches of the superior mesenteric artery (clockwise)
jejunal and ileal arteries
ileocolic artery
right colic artery
middle colic artery
what is the path of jejunal/ileal arteries
from superior mesenteric = pass between layers of mesentary and form anastomotic arcades
what are vasa recta
small straight arteries arising from anastomotic arcades of jejunal/ilial arteries
name 5 differences of the jejunum from the ileum
jejunum =
- wider
- thicker wall
- deep red
- few peyers patches
- long/fewer vasa recta
what does the middle colic artery supply
transverse colon
what does the right colic artery supply
ascending colon
at what level does the inferior mesenteric artery branch off the aorta
L3
name the 3 branches of the inferior mesenteric artery
- left colic artery
- sigmoid arteries
- superior rectal artery
what does the left colic artery supply
distal 1/3rd transverse colon and descending colon
what do the sigmoid arteries supply
descending colon and sigmoid colon
what does the superior rectal artery supply
= continuation of inferior mesenteric artery supplying the rectum
what is the colon
large intestine
describe the muscle in the wall of the colon
longitudinally running = teniae coli
which vein drains blood from the colon and where to
inferior mesenteric vein drains to splenic vein
where does lymph from small bowel drain
superior/inferior mesenteric nodes then to lymphs trunks then to cisterna chyli then into thoracic duct
name 4 anatomical features of small bowel that increase SA
- long
- plicae circularis
- villi
- microvilli
mesentery and the small bowel
ascending/descending = retroperitoneal transverse/sigmoid = in a mesentery
what are haustra
small pouches caused by sacculation of teniae coli = give segmented appearance
what are appendices epiploicia
small puches of peritoneum filled with fat along colon
what part of the bowel is supplied by the sacral nerves 2,3,4
= produce pelvic splanchnic nerves = parasympathetic of hindgut
what forms the common bile duct
common hepatic duct and cystic duct
how many pancreatic ducts are there
2 = main and accessory = represent dorsal/ventral buds from foregut in embryology
why is pain from the viscera referred
referred to areas of skin (dermatomes) supplied by same sensory ganglia/spinal cord segments as nerve fibres innervating viscera
