Small Intestine, Large And Portal System

Front 1

describe general characteristics of jejunum and ileum and differentiate

Back 1

-20 feet long; both intraperitoneal completely enclosed in visceral peritoneum which reflects from intestine to form a 2 layered mesentery attached to posterior abdom wall with vessels (superior mesenteric vessels and lymphatics) run in between
-2/5 jejunum upper left quadrant
-3/5 ilieum right lower quadrant
-2 continuous layers of smooth muscle, jejunum narrower lumen, ileal surface appears smoother
-inner surface (mucosa) of jejunal has modified circular folds- plicae circulares
-Jejunum deeper red, wider lumen, thicker wall, large tall densely packed mucosa, few-none lymphoid elements, root of mesentery superior left of aorta, fat free windows, 1-2 loops and long
-Ileum paler, thinner lumen and wall, mucosa is low sparse and/or absent, Peyer's patches- lymphoid elements (most numerous in terminal), inferior right of aorta root of mesentery, 4 or more arcades, short

Front 2

describe the contents of the mesentery

Back 2

-superior mesenteric vessels give rise to intestinal branches that branch to form networks called arcades
-arcades of the jejunum form 1-2 arches; ileum 4 or more
-terminal arteries called vasa rectae branch from arcades to run to wall of small intestine; jejunum- long, ileum are short

Front 3

describe path of superior mesenteric artery and vein

Back 3

-arises from abdom aorta just below celiac and runs down posterior to neck of pancreas and ant to 3rd part of the duodenum
-12-15 intestinal branches from left side to jejunum and ileum
-ileocolic artery arises from right side, running toward cecum and may supply terminal portion of ileum
-vein ascends on right side of artery; drains into splenic which forms protal vein

Front 4

describe meckel's diverticulum

Back 4

-remnant of vitelline duct of the embryo; in the early embryo, the gut is connected to the yolk sac via this duct
-found in 2% of population, usually 2 ft from ileocecal junction and is 2 in long on anti-mesenteric surface of ileum and may become inflamed and mimic appendicitis

Front 5

describe the large intestine wall and structures

Back 5

-cecum, ascending colon, transverse colon, descending colon
-outer longitudinal muscle layer is discontinuous and forms 2 bands- teniae coli which start at the base of the appendix
-the muscle bands are shorter than the intestine and cause surface to pucker forming saccules called haustra coli
-inner surface mucosa is smooth but has shelf-like folds between hausfrau called semilunar folds
-large intestine has fat tags called epiploic appendices

Front 6

describe the cecum

Back 6

-blind end pouch located inferior to level of ileocecal junction and valve in the right iliac fossa
-ileocecal valve is bordered by 2 folds of mucosa that do not actively control movement of fluid through the valve
-opening to vermiform appendix is on posteromedial side
-appendix is intraperitoneal with its own mesoappendix attaching it to ileum; teniae coli converge at base of appendix

Front 7

describe peritoneal folds and recesses

Back 7

-at the transitions between intraperitoneal ileum and appendix and periotneal covered cecum, peritoneal folds are formed
-superior ileocecal fold is superior to ileum and between cecum and mesentery
-inferior fold is inferior to ileum
-recesses below each fold
-retrocecal recess below cecum

Front 8

describe the blood supply to the cecum

Back 8

-ileocecal branch of superior mesenteric art runs toward cecum and divides into superior and inferior branches
--superior branch runs up to join right colic artery from SAM
--inferior branch gives rise to anterior and posterior cecal art
---anterior cecal art runs in superior ileocecal fold to supply cecum
---post cecal art descends deep to ileum to mesoappendix and supplies appendicular art

Front 9

describe position of appendix and appendicitis

Back 9

-3-5 in long, intraperitoneal
-base is farily stable in position at McBurney's point- 1/3 of distance from anterior superior iliac spine to umbilicus
-tip position is variable, most often found retrocecal position or sometimes pelvic location

-appendicitis most commonly caused by occlusion of orifice followed by infection
-intial pain felt is vague, referred pain due to stretching of visceral peritoneum at T10 around umbilical region
-with inc inflammation and/or infection appendix contacts parietal peritoneum and sharp, localized somatic pain is felt over McBurney's point within right lower quadrant

Front 10

describe ascending and transverse and descending

Back 10

-ascending- 5 in long; contacts right lobe of liver
-transverse 15 in long; in umbilical region; left is superior to right, transition from midgut to hind gut in blood and nerve supply; transverse mesocolon connects transverse colon to post abdom wall
-descending 10 in long; spelnic flexure is attached to phrenicocolic ligament which tethers flexure to diaphragm and forms a support for spleen which also contacts flexure

Front 11

describe blood supply to large intestine and venous drainage and lymphatics

Back 11

SMA- ileocolic art to cecum, appendix and terminal ileum
-ileocolic to right colic art- supplies ascending colon to hepatic flexure
-middle colic art supplies all but distal part of transverse colon
-IMA- left colic art that supplies distal portion of transverse colon and descending colon
-sigmoid branches from IMA supply remainder of descending colon
-marginal art of drummond- arterial channel near mesenteric border of colon; functional anastomosis between SMA and IMA
-SMV- entire colon up to distal end of transverse colon
-IMV- distal of transverse colon to sigmoid
-lymph-IM nodes to intestinal trunk to SM nodes to celiac nodes to cysterna chyli

Front 12

describe nerve supply

Back 12

-stomach- proximal 2/3 of transverse colon- vagal trunks via T5-T9 greater splanchnic nerves-celiac and superior mesenteric plexuses (stomach and duodenum) and T10-11 superior mesenteric plexus sympathetic, vagus trunks parasympathetic
-distal 1/3 transverse colon and descending colon L1-L2 lumbar splanchnics via inferior mesenteric plexus, S2-S4 parasympathetic
-sympathetic fibers origin will indicate level to which pain will refer from these areas since afferents travel with splanchnic nerves