GI Anatomy Flashcards
The GI is embryologically derived from this
mesoderm
Name the three parts of the GI and what they are supplied from
foregut - celiac trunk, midgut - superior mesenteric, hindgut - inferior mesenteric
What does the foregut give rise to
esophagus, stomach, proximal half of dueodenum, liver, gallbladder, and pancreas
what does the midgut give rise to
distal half of duodenum, SI, proximal half of large intestine up to proximal 2/3 of transverse colon
What does the hindgut give rise to
Distal 3rd of the transverse colon to the proximal half of the anal canal
What is Meckel’s diverticulum and its characteristics (2s)
Uncommona congenital anomaly (2% of population, 2x more common in males), 2 inches long, located 2 feet proximal to iliocecal junction, and may contain 2 types of ectopic tissue (gastric and pacreatic)
Name the 6 layers, external to internal, of the anterior abdominal wall
skin, subcutaneous tissue, muscle, transversalis fascia, extraperitoneal fat, and parietal peritoneum
Name the two layers of the subcutaneous tissue
Fatty layer (camper) and membranous (Scarpa) - only exists in lower abdomen
The membranous layer of the abdomen extends to these areas
extends medially and inferiorly to continue with colles fascia in the scrotum and buck’s fascia around the penis
It is attached to the base of the urogenital diaphragm
Extends below inguinal ligament to join the tensor fascia lata
What muscles are located lateral to the linea semilunaris in the abdomen
external oblique, internal oblique, and trnasversus abdominis
what muscels are located in the region medial to the linea simulunaris
rectus abdominis
What is the anterior abdominal wall innervated by
lower 5 intercostal nerves (T7-T11), the subcostal nerve (T12) and the iliohypogastric and ilioinguinal nerves (L1)
contents of the rectus sheath
rectus abdominis, pyramidalis (absent in 15%), and superior and inferior epigastric a, and v,
What is the inner lining of the abdominal cavity called
peritoneum
Which layer of the peritoneum is sensitive to pain and what is its innervation
parietal - lower intercostal and subcostal nerves like the anterior abdominal wall
The visceral layer is not sensitive to pain but sensitive to distension
Which peritoneum of the abdominal cavity is located behind the stomach
lesser sac
Through which opening does the lesser sac communicate with the greater sac
epiploeic foramen of winslow
Most of the intra-abdominal organs are covered completely by peritoneum, those that are only covered anteriorly by peritoneum are refereed to as this
retroperitoneal
Name the retroperitoneal structures (AS DC PARK AID)
Ascending Colong, Descending Colon, Pacnreas, Adrenals, Rectum (lower2/3), Kidneys, Aorta, IVC, Duodenum (2nd to 4th parts) (AS DC PARK AID)
Name the cells of the stomach and the muscular layers
columnar epithelium
outer - longitudinal, inner-circular, and innermost-oblique
Name the two main cell types of the stomach and their secretions
Chief cells - pepsinogen
Parietal (oxynitic) - HCL and intrinsic factor
Name the arteries that supply the stomach
left gastric - from celiac trunk, right gastric - from common hepatic or hepatic artery proper, left gastro-epiploic and short gastric - from splenic artery, right gastro-epiploic - from the gastro-duodenal branch of hepatic artery proper
What part of the duodenum does the common bile duct of the billiary tree open into
2nd or descending part
what part of the duodenum does the superior mesenteric vein and artery pass over
3rd or horzontal
what is fixed to the duodeno-jejunal junction
supsensory ligament of Treitz, which is in turn attached to the right crus of the diagram
What portion of the duodenum is intraperitoneal
first inch of the first part
Callot’s triangle located between the cystic duct, common hepatic duct, and the liver contains this artery
cystic
what is the proximal part of the small intestine called and what are its characteristics
jejunum - it is thicker, wider, and less vascular
what is the distal party of the small intestine called and what are it’s chracteristics
ileum - thinner, narrower, and less vascular
Describe the mesentery in the different parts of the small intestine
jejunum - large translucent windows, few large vascular arcades with longer and fewer vasa recta
ileum - small opaque windows, numerous small arcades and numerous vasa recta
What is the name of the numerous lymphoid aggregates located in the ileum
Peyer’s patches (Gut Associated Lymphoid Tissue)
What artery supplies all of the SI and LI up to the proximal 2/3s of the transverse colon
superior mesenteric
Differentiate between the small and large intestine
LI - has haustra, teniae coli, appendices epiploica and a large diameter
SI - has none of these things
What are the locations of the appendix
behind cecum (55%) in pelvis (30%) either retro-ileal or pre-ileal (5%)
Where is the base of the appendix located
McBurney’s point - 2/3 along a line from the umbilicus to the asis
Name the blood supply to the rectum
superior rectal branch via inferior mesenteric artery
the rectum becomes the anal canal once it passes through this
pelvic diaphragm
what to embryological origins is the anal canal derived form
endoderm and ectoderm
What is the junction between the two embryological origins called
pectinate line
What are the longitudinal folds above the pectinate line called
columns of Morgagni
columns of Morgagni are connected inferiorly by mucosal folds called this
valves of Ball (anal glands open behind these valves
What is the external rectal branch innervated by
inferior rectal branch of the pudendal nerve
Differentiate between the upper and lower half of the anal canal separated by the pectinate line
Upper half - endoderm, insensitive to pain, blood and lymphatic supply/drainage is via inferior mesenteric
Lower half - ectoderm, sensitive to pain, blood supply via inferior rectal branch of internal pudendal, lymphatics drain into the superificial inguinal nodes in the groin
