Abdominal Cavity

peritoneal cavity: subset of the abdominal cavity lined by continuous serous membrane called peritoneum

peritoneal cavity is really only a potential space; may be filled in pathologic conditions (i.e. ascites)
peritoneum is separated from the transversalis fascia by a fatty layer (extraperitoneal fat)
visceral and parietal peritoneum and mesentaries are all one continuous membrane
arietal peritoneum: lines the abdominal wall
visceral peritoneum: forms outer, serous covering of organs

greater and lesser sacs (bursa): the peritoneum is divided into two developmental spaces

greater sac is larger and contains the peritoneal organs (remnant of left pleuroperitoneal space)
lesser sac is retrogastric and is a potential space (remnant of right pleuroperitoneal space)

Omental Foramen (Epiploic Foramen of Winslow): connects the sacs Þ potential herniation site

anterior boundary: free edge of lesser omentum (portal vein, hepatic artery, bile duct)

posterior boundary: IVC, crus of diaphragm

superior boundary: liver

inferior boundary: duodenum, portal vein, hepatic artery, bile duct

mesentaries: double layer of peritoneum formed by punching in of organs during development (see fig)

named for organs it covers (i.e. mesocolon, mesogastrium)
connects organs to abdominal wall, but allows them to be mobile
blood vessels, nerves and connective tissue are sandwiched between the two layers of the mesentary

peritoneal ligaments: structures analogous to mesentaries connecting two organs (i.e. gastrosplenic ligament connnects stomach to spleen)

intraperitoneal structures: enveloped by the peritoneum and attached to abdominal wall by mesentaries

stomach, 1^st part of duodenum, jejunum, ileum, cecum, appendix, transverse colon, sigmoid colon, liver (except bare area), spleen

primarily retroperitoneal: never surrounded by peritoneum

kidneys, aorta, IVC, rectal canal, ureters, suprarenal glands

secondarily retroperitoneal: initially were intraperitoneal, but through development became apposed and fused to the abdominal wall either directly or through apposition of the mesentary

ascending and descending colon, duodenum (parts 2-4), head and body of pancreas

peritoneal recesses: blind pouches (potential spaces) formed by the complex folding of the peritoneum

potential sites of fluid (or pus, feces, etc) accumulation; provide surgical access; potential hernia sites

greater omentum: fatty, 4-layered ‘apron’ formed by a large flap of mesentary folded onto itself and fused together (see fig)

connects stomach to posterior abdominal wall and diaphragm
hangs down off greater curvature of stomach and covers intestines
secretes and absorbs peritoneal fluid; source of macrophages
has mobility, can seal off inflamed areas of the peritoneum to prevent spread of infections; remnant of dorsal mesentery

lesser omentum: connects lesser curvature of stomach and duodenum to the liver

contains hepatogastric ligament, hepatoduodenal ligament
remnants of ventral mesentary

four parts of duodenum – 1^st is movable, others are immobile

accessory and main pancreatic duct (pancreatic and bile duct) – into 2^nd part of duodenum

suspensory ligament (ligament of Treitz) – smooth and striated muscle at junction of duodenum and jejunum

Structures

peritoneum: lines the abdominal cavity

peritoneal cavity: formed by peritoneum (closed sac except in infundibulum of each uterine tube in females)

serous coat: outer lining of peritoneum that covers an organ when it invaginates the peritoneum

peritoneal folds (plicae): peritoneum with a free edge raised up off of the abdominal wall, usually by a vessel or

ligament running between the peritoneum and the abdominal wall

medial umbilical folds: cover medial umbilical ligaments (obliterated umbilical arteries)

median umbilical fold: covers median umbilical ligament (remnant of urachus)

lateral umbilical folds: cover inferior epigastic arteries

lesser omentum: connects lesser curvature and duodenum to the liver – has two parts:

hepatogastric ligament: connects liver and stomach

hepatodudenal ligament: connects liver and duodenum

greater omentum: hangs from greater curvature; mesentary doubled back to give a four-layer flap of peritoneum

mesentary: double layer of peritoneum formed by punching in of organ from posterior abdominal wall

attaches organ to abdominal wall; allows movement; blood vessels and nerves run between folds

ligamentum teres: free edge of falciform ligament (remnant of umbilical vein)

diaphragm: note the extent of the doming Þ wounds can potentially penetrate both the peritoneum and pleura

liver:

falciform ligament: divides liver into two lobes (right and left); attaches liver to anterior abdominal wall

bare area of liver: pertioneum reflects away from the liver in the posterior leaving an uncovered area

coronary ligament: peritoneal reflections around bare area; ligament running along superior margin of liver

right and left triangular ligament: right and left portion of coronary ligament, respectively

gall bladder: protrudes beyond the inferior border of the liver; projects to the lateral margin of the rectus abdominus also contacts duodenum and large bowel

stomach:

pylorus: connects the stomach to the duodenum; identified as firm area by palpation

greater and lesser curvatures

spleen: posterior to stomach, in contact with diaphragm

gastrolineal (gastrosplenic) ligament: double layer of peritoneum; connects spleen and stomach

head, neck, body, tail

small intestine: total length is 6 m

duodenum: begins at pylorus; first part is intraperitoneal; second, third and fourth parts are retroperitoneal

ligament of Treitz: suspends fourth part of the duodenum at the duodenal-jejunal junction – connects to diaphragm at right crus

jejunum: proximal 2/5 of the mobile part of the small intestine

ilium: distal 3/5 of the mobile part of the small intestine; opens into superior part of cecum

large intestine:

cecum: blind pouch at proximal end of large bowel; ileocecal junction is at superior part

veriform appendix: narrow, blind tube that connects to the cecum inferior to the ileocecal junction

ascending colon: retroperitoneal; has no mesentary

transverse colon: intraperitoneal; extends from right colic flexure to left colic flexure

decending colon: smaller diameter than ascending colon; retroperitoneal

sigmoid colon: has long mesentary and is very mobile

rectum: stores feces; only partially covered by peritoneum; actually considered part of pelvic region

teniae coli: muscles that run longitudinally along the colon; derived from longitudinal smooth muscle (three)

haustra: sacculations along the colon resulting because the teniae coli are shorter than the colon

epiploic appendices: small bags of visceral peritoneum filled with fat; hang off the colon along its length

right colic flexure: junction of ascending and transverse colon - at inferior tip of left lobe of the liver

left colic flexure: junction of transverse and descending colon - at inferior border of spleen

epiploic foramen of Winslow: connects greater and lesser peritoneal sacs (potential herniation site)

anterior boundary: free edge of lesser omentum (portal vein, hepatic artery, bile duct)

posterior boundary: IVC, crus of diaphragm

superior boundary: liver

inferior boundary: duodenum, portal vein, hepatic artery, bile duct

root of mesentery: refers to mesentery of small intestine; runs obliquely from left side of L2 to the right sacroiliac joint

peritoneal gutters: mesentaries can form gutters that can conduct fluid around the peritoneal cavity

right paracolic gutter: to the right of the ascending colon

left paracolic gutter: to the left of the descending colon

right infracolic gutter: to the left of the ascending colon

left infracolic gutter: to the right of the descending colon

hepatorenal recess: posterior to the liver, anterior to right kidney; site of fluid accumulation in supine position

subphrenic recess (right and left): anterior to liver, posterior to anterior abdominal wall