Intestines Flashcards
Plicae circulares
Mucosal folds covering the luminal (inner) surface
Duodenum
. Secondarily retroperitoneal . Adjacent to the pylorus . Thickness of 12 fingers . C-shaped . Cradles the head of the pancreas . Sup. Portion, descending portion, horizontal portion, ascending portion
Sup. Portion of duodenum
. Has mesentery, more mobile
. Has smooth wall area of duodenal cap or bulb
. Plicae circulares begin 3-5cm from pylorus
Duodenal ulcers
. Post wall of sup. Part of the duodenum near the pylorus
. Can lead to peritonitis if stomach contents enters peritoneal cavity
Descending portion of duodenum
. Courses inf. To the right of L1-3 vertebrae
. Located parallel and to the right of the IVC
. Contains combined openings of bile duct and pancreatic ducts
. Major duodenal papilla w/ ostium: assoc. w/ chief or moan pancreatic duct and bile duct forming hepatopancreatic ampulla
. Minor duodenal papilla w/ ostium: assoc. w/ accessory pancreatic duct
Horizontal portion of duodenum
. Crosses lower part of L3 body
. Sup. Mesenteric a. Arises above this
Duodenum ascending portion
. Ascends lat. to L2-3 vertebrae
. Located on the L side of the abdominal
. Turns ventrally to be continuous w/ jejunum at duodenal-jejunal flexure
. Recesses and fossae that can be possible sites for gut herniation
Suspensory ligament of duodenum
. Ligament of Treitz
. Fibromuscular band attached at flexure
. Attaches sup. To crus of diaphragm
Recesses in descending portion of duodenum
. Sup. Duodenal fold/recess: next to flexure
. Inf. Duodenal fold/recess: ant. To angle btw horizontal and ascending portions of duodenum
. Retroduodenal recess: post. To ascending portion
. Paraduodenal fold/recess: left of duodenum, covers, inf. Mesenteric v. And L colic a.
Jejunum
. Intraperitoneal
. No good demarcation from ileum (2/5 of combined length of jejunum and ileum)
. Frequently empty
. Wider diameter
. Thicker walls
. Redder from more vasculature
. Plicae circulares more prominent
. Blood vessels in mesentery (1-2 layers of arcades, long vasa recta)
. Features most prominent at proximal end
Ileum
. Intraperitoneal . Features most prominent at distal end . Narrower, thinner, paler . Small/absent plicae circulares . Inc. mesenteric fat . Blood vessels in mesentery (4-5 layers arcades, short Vasa recta) . Peyer’s patches . Meckel’s diverticula
Peyer’s patches
. Submucosal aggregates of lymph tissue along antimesenteric border
Meckel’s diverticulum
. Common malformation
. Finger-like blind pouch remnant of embryonic Vitelline duct
. 2% individuals 2” long 2 feet from iliocecal junction
. Mimic appendix symptoms if inflamed
Mesentery
. Fan shaped double layer peritoneum containing blood vessels, nerves, lymph
. Short root: 15 cm running obliquely (sup to inf, left to right) across post. A nominal wall from duodenal-jejunum flexure to iliocecal junction
. Long border: 6-7m at point of attachment to jejunum and ileum
Large intestine distinct surface characteristics
. Teniae coli: outer longitudinal muscle layer incomplete, forms 3 equally spaced bands
. Haustra or sacculation: teniae coli 1/6 shorter than rest of colon so gut wall bulges out
. Epiploic appendices: fat-filled appendages
Inner surface of large intestine
. Semilunar mucosal folds that run from teniae coli to teniae coli
Regions of large intestine
. Cecum w/ appendix . Ascending colon . Transverse colon . Descending colon . Sigmoid colon . Rectum . Anal canal
Cecum
. Blind pouch 6-7cm
. Secondarily retroperitoneal
. Ileum enters cecum at ileocecal orifice
Appendix
. Intraperitoneal (mesentery called mesoappendix)
. 2-20 cm long, avg 8 cm
. Appendicular orifice
. Opening 3 cm inf. To ileocecal valve
. Root is only fixed point
. Usually retrocecal (64%) or pelvic rim (32%)
. Frequently inflamed
McBurney’s point
. Junction of lat. and middle thirds of line joining ASIS to umbilicus
. Produces max abdominal pain in appendicitis
Ascending colon
. Secondarily retroperitoneal
. From cecum to R colic (hepatic) flexure
. Narrower than cecum
Transverse colon
. Intraperitoneal
. Largest and most movable part of large intestine
. Courses from R colic flexure to L colic (splenic) flexure
. Mesenteric attachments: post. To transverse mesocolon (courses across duodenum and pancreas) and ant. To gastrocolic ligament of greater omentum
Left colic flexure
. More sup. And post. Than right colic flexure
. Attached to diaphragm by phrenicocolic ligament
Descending colon
. Secondarily retroperitoneal
. From L colic flexure to sigmoid colon
. Narrowest part of colon
Sigmoid colon
. Intraperitoneal
. S-shaped loop
. V-shaped Mesenteric attachment running along post. Abdominal wall and pelvis (sigmoid mesocolon)
Preganglionic sympathetic fibers of intestines
. From sympathetic chain
. Synapse in sup. Or inf. Mesenteric (preaortic) ganglia
Postganglionic sympathetic fibers in intestines
. From sup. Mesenteric ganglia: follow blood vessels to midgut organs (distal 1/2 duodenum through prox. 2/3 transverse colon)
. From inf. Mesenteric ganglia: follow blood vessels to hindgut (distal transverse colon to rectum)
Sympathetic effect on intestines
. Dec. motility and secretion, vasoconstricts, constricts sphincters
. Visceral sensory afferents convey pain
Parasympathetic fibers in intestine
. Preganglionic: vagus to GI tract up to L colic flexure, sacral (pelvic splanchnics) to rest of organs
. Synapse in wall of gut (myenteric/submucosal plexuses)
. Short postganglionic fibers
Parasympathetic effects on intestine
. Inc. motility secretion, vasodilates, dilates sphincters
. Visceral sensory afferents conveys senses of nausea and distension
Sup. Mesenteric a.
. Unpaired, from abdominal aorta (L1)
. Lymph and nerve plexus at base
. Supplies SI, cecum, appendix, ascending colon and R 2/3 of transverse colon
Sup. Mesenteric a. Branches
. Inf. Prancreeaticoduodenal a. . Intestinal a (15-28 in mesentery to jejunum and ileum) forming arcades and vasa recta . Ileocolic a. . R colic a. . Middle colic. A.
Ileocolic a. Branches
. Cecal branches
. Colic branch (anastomoses w/ descending branches of R colic a.)
. Ileal branch (anastomoses w/ ileal branches)
. Appendicular branch
Percentage of ileocolic aa. That arise from common stem w/ R colic a.
40%
R colic a.
. Descending branch (anastomoses w/ colic branch of ileocolic a.)
. Ascending branch (anastomoses w/ middle colic a.)
Inf. Mesenteric a.
. Unpaired from abdominal aorta (L3) above bifurcation
. Lymph and nerve plexus at base
. Supplies left 1/3 transverse colon, descending colon, sigmoid colon, rectum
Inf. Mesenteric a. Branches
. L colic a.
. Sigmoidal aa. (2-3)
. Sup. Rectal a.
Left colic artery branches
. Ascending branch: anastomoses w/ L branch of middle colic a.
. Descending branch
Sigmoidal aa.
. Ascending branch
. Descending branch
Sup. Rectal a. And branches
. Inf. Continuation of inf. Mesenteric a. After last sigmoidal branch is given off
Marginal artery of Drummond
. Extensive anastomoses of branches of sup. And inf. Mesenteric aa.
. Patent arch around large intestines
Veins of intestines
. Sup. Mesenteric v, joins splenic v. To form portal v.
. Inf. Mesenteric v. Terminates in splenic v. (60%) or sup, mesenteric v. (40%)
Lymphatic trunks of intestines
. Abdominal (lumbar, intestinal, descending thoracic) converge to form cisterna chyli
Cisterna chyli
. Collects lymph from lower half of body
. Beginning of thoracic duct
Thoracic duct
. All lymph from lower half of body
. Enters venous system at convergence of L internal jugular and L subclavian vv.
T/F infants w/ pets have high diversity of microbes in gut leading to inc. gut. Immunity
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