U2 anatomy B - peritoneum/mesenteries, esophagus/stomach, SI & LI

peritoneum

serous membrane that lines the abdominal cavity

1. parietal peritoneum

>attached to abdominal and pelvic walls

2. peritoneal cavity

>space between parietal and visceral peritoneum

>serous fluid

3. visceral peritoneum

>covers organs

peritoneal folds

form omenta, mesenteries, and ligsments

anchor and suspend organs from abdominal walls

greater omentum

vascularized, apron-like structure that drapes over the small intestine and transverse colon; a site of fat deposition in people who are overweight

contains right and left gastroepiploic arteries/veins

fatty double layered membrane

"policeman" of the abdomen

bowel inflammation and infection

inflamed bowel = no peristalsis

greater omentum migrates via peristalsis of non diseased bowel to site of infection

greater omentum

first structure seen in laparotomy

direct spread common for carcinoma of ovary

omentum thickens as metastases develop

lesser omentum

lesser curvature of stomach and duodenum to inferior surface of liver

contains hepatic artery proper, hepatic portal vein, bile duct, left and right gastric artery/vein

mesenteries

peritoneal folds that attach viscera to the posterior abdominal wall

function

movement, position of organs, conduit for vessels

types of mesenteries

-mesentery proper

-transverse mesocolon

-sigmoid mesocolon

-mesoappendix

mesentery proper

aka mesentery

attaches small intestine (jejunum and ileum) to posterior abdominal wall

runs from junction between duodenum and jejunum, to the left of the vertebral column, runs down on a diagonal to junction between ileum and cecum

contains AVN that supply jejunum/ileum

transverse mesocolon

transverse colon

attaches transverse colon to posterior abdominal wall

contains AVN that supply the transverse colon

anterior portion is attached to greater omentum

sigmoid mesocolon

sigmoid colon

attaches sigmoid colon to pelvic wall

contains arteries that supply the sigmoid colon

mesoappendix

suspends appendix to ileum

contains appendicular AV

ligaments

not really ligaments, but folds of peritoneum that attach an organ to a body wall

falciform ligament

ligament of treitz

intraperitoneal

suspended from the abdominal wall by mesenteries

surrounded by visceral peritoneum

stomach, first part of duodenum, jejunum, ileum, cecum, appendix, transverse colon, sigmoid colon, upper 1/3 rectum, liver, spleen, tail of pancreas, ovaries

retroperitoneal

not suspended from the abdominal wall by mesenteries

lie between the parietal peritoneum and abdominal wall

partial surrounded by peritoneum

last part of duodenum, ascending colon, descending colon, portion of rectum, kidneys, ureters, bladder, uterus, fallopian tubes, adrenal glands, inferior vena cava, aorta

secondarily retroperitoneal

last part of duodenum, ascending colon, descending colon, portion of rectum

during development, suspended by mesentery

later become retroperitoneal in position by secondarily fusing with abdominal wall

alimentary canal organs

esophagus, stomach, small intestine, large intestine

accessory digestive organs

liver, pancreas, gallbladder

esophagus

long muscle posterior to the trachea

C-shaped rings in trachea allow bolus to move through esophagus

passes through diaphragm to abdomen at esophageal hiatus

leads to stomach

ends at cardiac orifice of stomach (opening into stomach)

cardiac sphincter = muscular ring that prevents regurgitation

stomach

dilated part of GI tract

site of mechanical digestion, breakdown of food

left Side of Body

partially covered by liver

stomach

parts

-greater curvature

-lesser curvature

-fundus

-cardial notch

-body

-pylorus

-pyloric antrum

-pyloric canal

-pyloric orifice

-pyloric sphincter

small intestine

the pyloric sphincter is the division btw stomach and small intestine

6-7m long

functions

site of chemical digestion of food

absorption of nutrients

regions

-duodenum

-jejunum

-ileum

duodenum

1st part of small intestine

C-shaped portion following stomach

20-25cm long

above level of umbilicus

A in photo

superior part of duodenum

goes from pyloric orifice to neck of gallbladder to right of body L1

- AKA ampulla or duodenal cap

-common site for duodenal ulcers

descending part of duodenum

goes from neck of gallbladder to lower border L3

anterior surface is crossed by transverse colon

lateral to head of pancreas

contains major duodenal papilla = common entrance of bile and pancreatic ducts

minor duodenal papilla = accessory pancreatic duct

inferior part of duodenum

longest section

-crosses over inferior vena cava, aorta, vertebral column

ascending part of duodenum

passes upward on/to left of aorta

ends at duodenojejunal flexure

duodenojejunal flexure

ascending duodenum bends to become jejunum

very apparent bend

asociated with Ligament of Treitz

ligament of treitz

ligament that supports the duodenojejunal junction.

suspensory muscle of the duodenum

peritoneal fold with muscle fibers

anchors the SI

clinically is a landmark in surgery for finding end of duodneum, start of jejunum, and involved in birth defect causing malrotation of the small intestine

jejunum

2nd portion of small intestine

proximal two fifths of SI

primarily in upper left quadrant

larger diameter, thicker wall than ileum

many prominent folds internally •

long straight arteries supplying it = vasa recta

B

ileum

3rd portion of small intestine

distal three fifths of SI

primarily lower right quadrant

thinner walls, smaller diameter, less folds

short, complex arterial branching >short vasa recta

C

jejunum

long, straight arteries with simple branches

ileum

short, complex arterial branching

ileocecal fold

where ileum opens into large intestine

flaps surrounding opening

project into lumen of large intestine

sphincter to prevent reflux from large intestine to small

large intestine

function = absorption of water

ONLY digestion occurs via enteric bacteria

propulsion of feces towards anus

NOT necessary for life

1.5 m long

large = refers to diameter

five distinct regions

cecum, appendix, colon, rectum, anal canal

found in all quadrants - "frame" around small intestine

large intestine

features include taeniae coli, haustra, omental appendices

cecum

end of ileum and start of large intestine

pouch on right side sitting near iliac fossa and crest

appendix

worm-like extension off cecum made of primarily lymphoid tissue

on the right side

function

storage of "good bacteria?"

appendicitis

-obstructed by fecalith

-enlargement of lymphoid nodules

-bacteria proliferate

appendix placement

highly variable!

-postileal = posterior to ileum

-pre-ileal = anterior to ileum

-pelvic

-subcecal = inferior to cecum

-retrocecal = posterior to cecum

ascending colon

running up the right side of the body

right colic/hepatic flexure

90 degree bend

transition from ascending to transverse colon

transverse colon

2nd part of colon

horizontal

left colic/splenic flexure

90 degree turn

transition from transverse colon to descending colon

descending colon

running down left side of body

ends when it flexes/turns to form sigmoid colon

sigmoid colon

starts at pelvic brim, extends to S3

S shaped

continues with rectum

vertically oriented

rectum

level of S3 to coccyx

pierces pelvic diaphragm

anal canal