Anatomy Flashcards
What are the boundaries between the foregut, midgut and hindgut?
Foregut ends at the entrance of bile duct in second part of duodenum.
Midgut ends between proximal 2/3 and distal 1/3 of transverse colon
How do all gut structures begin with regards to relationship to mesentery?
They all begin with dorsal mesentery (peritoneal)– Some lose dorsal mesentery to become secondarily retroperitoneal (in midgut/hindgut)
What are secondarily retroperitoneal organs? (5)
Duodenum (2nd/3rd parts) Head/neck/body of pancreas Ascending colon Descending colon Upper rectum
What structure is remnant of umbilical vein?
Round ligament of liver
What are three constrictions of esophagus?
Cervical (around C6)
Thoracic: Where aortic arch is
Diaphragmatic
Describe the muscle breakdown of the esophagus. What is its innervation?
Upper 5%: Voluntary skeletal muscle
Middle 45%: Mixture of skeletal/smooth muscle
Lower 50%: Involuntary smooth muscle
All are innervated by vagus nerve
What is the Z line?
Transition between esophageal and stomach epithelium– squamo-columnar junction
Name some branches of celiac trunk
Common hepatic artery, gastroduodenal artery (can be eroded by ulcer), Left gastric artery, splenic artery (fundus, greater curvature, pancreas, spleen)
What are parts of the duodenum? What is the important landmark?
There are 4 parts of duodenum. The first 1.5 parts are in the foregut– after the entrance of the bile duct, the next 2.5 parts constitute part of the midgut
What is the blood supply for the duodenum?
The GDA supplies much of the duodenum as well as the head of the pancreas– there are anterior/posterior superior pancreatic-duodenal arteries
The midgut portions are supplies by the SMA
What is the name of the entry for the pancreatic/bile duct?
Major duodenal papilla
What is the difference in mucosa between jejunum and ileum?
Ileum is grooved (looks fuzzy on contrast imaging) whereas cecum is smooth
What are Peyer’s patches
Big patches of lymphatic tissue
What is the difference in blood supply between jejunum and ileum?
Jejunum: Simple arcades, long vasa recta
Ileum: Complex arcades, short vasa recta
What are three anatomic features of colon?
Taenia coli: Strips of smooth muscle
Haustrations: Pocket like folds
Epiploic appendages: Little fat things
Describe blood supply for colon
Part SMA, part IMA.
SMA: ileocolic artery (ascending colon) with appendiular artery (appendix), middle colic artery ( transverse colon)
IMA: Left colic artery (distal 3rd of transverse and descending), sigmoid arteries (sigmoid colon), superior rectal artery
If there were a sudden drop in arterial blood pressure where would you se bowel ischemia? Why?
At the splenic flexure– it’s the transition point between blood supply SMA and IMA
What is the difference between the two anal sphincter?
The internal anal sphincter is smooth muscle
External anal sphincter is skeletal muscle under voluntary control (pudendal nerve)
How far does vagal innervation go in GI?
End of midgut
Where does innervation for handgun come from?
Spinal nerves (pelvic splanchnic nerves) from S2-S4
Describe sympathetic innervation for Foregut/midgut and hindgut
Foregut: T5-T9
Midgut: T9-T12
Hindgut: L1-L2
How is pain from abdominal viscera carried back to CNS? How is it referred?
It’s carried by sympathetic nerves and is referred to dermatomes of body wall and is poorly localized.
