GI Anatomy

Question 1

The GI is embryologically derived from this

Answer 1

mesoderm

Question 2

Name the three parts of the GI and what they are supplied from

Answer 2

foregut - celiac trunk, midgut - superior mesenteric, hindgut - inferior mesenteric

Question 3

What does the foregut give rise to

Answer 3

esophagus, stomach, proximal half of dueodenum, liver, gallbladder, and pancreas

Question 4

what does the midgut give rise to

Answer 4

distal half of duodenum, SI, proximal half of large intestine up to proximal 2/3 of transverse colon

Question 5

What does the hindgut give rise to

Answer 5

Distal 3rd of the transverse colon to the proximal half of the anal canal

Question 6

What is Meckel’s diverticulum and its characteristics (2s)

Answer 6

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)

Question 7

Name the 6 layers, external to internal, of the anterior abdominal wall

Answer 7

skin, subcutaneous tissue, muscle, transversalis fascia, extraperitoneal fat, and parietal peritoneum

Question 8

Name the two layers of the subcutaneous tissue

Answer 8

Fatty layer (camper) and membranous (Scarpa) - only exists in lower abdomen

Question 9

The membranous layer of the abdomen extends to these areas

Answer 9

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

Question 10

What muscles are located lateral to the linea semilunaris in the abdomen

Answer 10

external oblique, internal oblique, and trnasversus abdominis

Question 11

what muscels are located in the region medial to the linea simulunaris

Answer 11

rectus abdominis

Question 12

What is the anterior abdominal wall innervated by

Answer 12

lower 5 intercostal nerves (T7-T11), the subcostal nerve (T12) and the iliohypogastric and ilioinguinal nerves (L1)

Question 13

contents of the rectus sheath

Answer 13

rectus abdominis, pyramidalis (absent in 15%), and superior and inferior epigastric a, and v,

Question 14

What is the inner lining of the abdominal cavity called

Answer 14

peritoneum

Question 15

Which layer of the peritoneum is sensitive to pain and what is its innervation

Answer 15

parietal - lower intercostal and subcostal nerves like the anterior abdominal wall

The visceral layer is not sensitive to pain but sensitive to distension

Question 16

Which peritoneum of the abdominal cavity is located behind the stomach

Answer 16

lesser sac

Question 17

Through which opening does the lesser sac communicate with the greater sac

Answer 17

epiploeic foramen of winslow

Question 18

Most of the intra-abdominal organs are covered completely by peritoneum, those that are only covered anteriorly by peritoneum are refereed to as this

Answer 18

retroperitoneal

Question 19

Name the retroperitoneal structures (AS DC PARK AID)

Answer 19

Ascending Colong, Descending Colon, Pacnreas, Adrenals, Rectum (lower2/3), Kidneys, Aorta, IVC, Duodenum (2nd to 4th parts) (AS DC PARK AID)

Question 20

Name the cells of the stomach and the muscular layers

Answer 20

columnar epithelium

outer - longitudinal, inner-circular, and innermost-oblique

Question 21

Name the two main cell types of the stomach and their secretions

Answer 21

Chief cells - pepsinogen

Parietal (oxynitic) - HCL and intrinsic factor

Question 22

Name the arteries that supply the stomach

Answer 22

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

Question 23

What part of the duodenum does the common bile duct of the billiary tree open into

Answer 23

2nd or descending part

Question 24

what part of the duodenum does the superior mesenteric vein and artery pass over

Answer 24

3rd or horzontal

Question 25

what is fixed to the duodeno-jejunal junction

Answer 25

supsensory ligament of Treitz, which is in turn attached to the right crus of the diagram

Question 26

What portion of the duodenum is intraperitoneal

Answer 26

first inch of the first part

Question 27

Callot's triangle located between the cystic duct, common hepatic duct, and the liver contains this artery

Answer 27

cystic

Question 28

what is the proximal part of the small intestine called and what are its characteristics

Answer 28

jejunum - it is thicker, wider, and less vascular

Question 29

what is the distal party of the small intestine called and what are it's chracteristics

Answer 29

ileum - thinner, narrower, and less vascular

Question 30

Describe the mesentery in the different parts of the small intestine

Answer 30

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

Question 31

What is the name of the numerous lymphoid aggregates located in the ileum

Answer 31

Peyer's patches (Gut Associated Lymphoid Tissue)

Question 32

What artery supplies all of the SI and LI up to the proximal 2/3s of the transverse colon

Answer 32

superior mesenteric

Question 33

Differentiate between the small and large intestine

Answer 33

LI - has haustra, teniae coli, appendices epiploica and a large diameter SI - has none of these things

Question 34

What are the locations of the appendix

Answer 34

``` behind cecum (55%) in pelvis (30%) either retro-ileal or pre-ileal (5%) ```

Question 35

Where is the base of the appendix located

Answer 35

McBurney's point - 2/3 along a line from the umbilicus to the asis

Question 36

Name the blood supply to the rectum

Answer 36

superior rectal branch via inferior mesenteric artery

Question 37

the rectum becomes the anal canal once it passes through this

Answer 37

pelvic diaphragm

Question 38

what to embryological origins is the anal canal derived form

Answer 38

endoderm and ectoderm

Question 39

What is the junction between the two embryological origins called

Answer 39

pectinate line

Question 40

What are the longitudinal folds above the pectinate line called

Answer 40

columns of Morgagni

Question 41

columns of Morgagni are connected inferiorly by mucosal folds called this

Answer 41

valves of Ball (anal glands open behind these valves

Question 42

What is the external rectal branch innervated by

Answer 42

inferior rectal branch of the pudendal nerve

Question 43

Differentiate between the upper and lower half of the anal canal separated by the pectinate line

Answer 43

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