SMA and IMA Flashcards
Targets of the SMA
Pancreas, duodenum, jejunum, ileum, cecum, appendix, ascending colon, transverse colon
Which part of the pancreas is retroperitoneal?
All of it except the tip of the tail
What is the relationship of the SMA and SMV to the pancreas
They pass over the uncinate process
Where do pancreatic duct and common bile duct merge
Hepatopancreatic ampulla
Where does the accessory pancreatic duct empty?
The minor duodenal papilla
What is the function of the duodenum?
Major site of chemical digestion because this is where chyme mixes with pancreatic juice and bile
What part of the duodenum is intraperitoneal?
The superior proximal portion
What are the four segments of the duodenum?
Superior, descending, horizontal, and ascending
Hepatoduodenal ligament
In addition to containing the portal triad, it anchors the superior portion of the duodenum to the liver
Suspensory muscle
Anchors ascending portion of duodenum to the diaphragm. Controls flow from duodenum to jejunum
Internal anatomy of superior duodenum
smooth wall because of duodenal ampula
Internal anatomy of the rest of the duodenum
Has folds of mucosa called plicae circulares
What is the relationship of the horizontal portion of the duodenum to the SMA and SMV
The SMA and SMV pass over the horizontal/transverse portion
Blood supply to pancreas
Pancreatic arteries from splenic artery
Superior pancreaticoduodenal arteries from gastroduodenal artery
Inferior pancreaticoduodenal arteries from superior mesenteric artery
Venous drainage of the pancreas
Pancreatic veins drain to splenic vein; pancreaticoduodenal veins drain to SMV
Lymphatics of pancreas
Pyloric nodes, or celiac nodes. Then into cistern chyli
Parasympathetic innervation of pancreas
Vagal trunks, autonomic plexuses
Sympathetic innervation of pancreas
Greater splanchnic nerve, celiac ganglion, autonomic plexuses
Function of small intestine
Majority of nutrient absorption
Is ileum and jejunum intra or retroperitoneal?
Intraperitoneal
Mesentery Proper
Anchors the ileum and jejunum to the posterior wall
Blood supply of ileum and jejunum
Superior mesentery artery runs in mesentery proper. It gives intestinal arteries that form anastomotic arcades and then give off vasa recta to supply the intestines directly.
Superior mesenteric vein
receives all blood from small intestines and delivers to hepatic portal vein
What is special about the blood draining in the superior mesenteric vein from the ileum and jejunum?
It’s very high in nutrient content!!!
Differences in jejunum and ileum
Jejunum is larger diameter, ileum has smaller diameter
Jejunum has very tall plicae circulares, ileum has Peyer’s Patches
Jejunem has very few and large arcades, ileum has small, numerous arcades
Jejunum has long vasa recta, ileum has short vasa recta
Function of large intestines
Absorption of water, vitamins; stores and compacts waste
Hepatic flexure
Right flexure between the ascending and transverse colon
In what space does the ascending colon lie
the right paracolic gutter, which has more communication than the left because the left is stopped by the phrenicocolic ligament
In what space does the descending colon lie?
The left paracocolic gutter
Splenic flexure
Left flexure between transverse and descending colon
Dividing line between midgut and hindgut
About 2/3 of the way across the transverse colon
Taenia Coli
Longitudinal muscle of the colon
Plicae semilunares
Gather colon into pouches called haustra. Semilunares are the folds on the inside
Blood supply to large intestine from SMA
ileocolic arteries, right colic artery and middle colic artery
Marginal artery
Anastomotic loop between ileocolic, right and middle colic arteries and between middle and left colic arteries
Venous drainage of midgut
All venous drainage of midgut follows arteries of the same name and drains into the SMV which merges with splenic vein to form hepatic portal vein
Lacteals
Lymphatics of midgut. They carry all dietary fats. These drain to the superior mesenteric nodes, then continue into cisterna chyli
Parasympathetic innervation of midgut
Parasympathetic vagal trunk
Sympathetic innervation of midgut
Thoracic splanchnic nerve (mostly lesser splanchnic)–> superior mesenteric ganglion.
Blood supply to hindgut from IMA
Left colic artery, sigmoid arteries, superior rectal artery
Location of sigmoid colon (intra or retro)
Intraperitoneal
Venous drainage of hindgut
Veins follow same name as arteries and drain to the inferior mesenteric vein which typically drains to splenic vein
Sympathetic innervation to hindgut
From lumbar splanchnic nerve (L1-L2) to inferior mesenteric ganglion
Parasympathetic innervation to hindgut
Pelvic Splanchnic nerves from S2, 3, and 4
Plicae circulares
Folds of mucosa in the duodenum that increase surface area for absorption
Inferior pancreaticoduodenal artery
Branch to pancreas coming directly off the SMA
Epiploic appendages
Fat filled pockets coming off of the taenia coli
intermesenteric plexus
blending of pelvic splanchnic preganglionic nerves and postganglionic sympathetic nerves.
