Wikia

Psychology Wiki

Peritoneum

Talk0
34,142pages on
this wiki
Revision as of 19:57, December 18, 2009 by Dr Joe Kiff (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)


Peritoneum
The peritoneum, coloured in blue
Latin '
Gray's subject #246 1149
System
MeSH A01.047.025.600
The epiploic foramen, greater sac or general cavity (red) and lesser sac, or omental bursa (blue). (Areas outlined in blue and red correspond to above diagram.)

The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal (or coelomic) organs — in higher vertebrates and some invertebrates (annelids, for instance). It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the abdominal organs and serves as a conduit for their blood and lymph vessels and nerves.

StructureEdit

LayersEdit

The abdominal cavity (the space bounded by the vertebrae, abdominal muscles, diaphragm and pelvic floor) should not be confused with the intraperitoneal space (located within the abdominal cavity, but wrapped in peritoneum). For example, a kidney is inside the abdominal cavity, but is retroperitoneal.

Although they ultimately form one continuous sheet, two types or layers of peritoneum and a potential space between them are referenced:

  • The outer layer, called the parietal peritoneum, is attached to the abdominal wall.
  • The inner layer, the visceral peritoneum, is wrapped around the internal organs that are located inside the intraperitoneal cavity.
  • The potential space between these two layers is the peritoneal cavity; it is filled with a small amount (about 50 ml) of slippery serous fluid that allows the two layers to slide freely over each other.
  • The term mesentery is often used to refer to a double layer of visceral peritoneum. There are often blood vessels, nerves, and other structures between these layers. It should be noted that the space between these two layers is technically outside of the peritoneal sac, and thus not in the peritoneal cavity.

SubdivisionsEdit

There are two main regions of the peritoneum, connected by the epiploic foramen:

The mesentery is the part of the peritoneum through which most abdominal organs are attached to the abdominal wall and supplied with blood and lymph vessels and nerves.

Structures include:

SOURCES STRUCTURE FROM TO CONTAINS
OMENTA
dorsal mesentery * greater omentum greater curvature of stomach (and spleen)
dorsal mesentery ** gastrosplenic ligament stomach spleen short gastric artery, left gastro-omental artery
dorsal mesentery ** gastrophrenic ligament stomach diaphragm left inferior phrenic artery
dorsal mesentery ** gastrocolic ligament stomach transverse colon right gastro-omental artery -
dorsal mesentery ** splenorenal ligament spleen kidney splenic artery, tail of pancreas
ventral mesentery * lesser omentum lesser curvature of the stomach (and duodenum)
ventral mesentery ** hepatogastric ligament stomach liver right & left gastric artery
ventral mesentery ** hepatoduodenal ligament duodenum liver hepatic artery proper, hepatic portal vein, bile duct
MESENTERIES
dorsal mesentery * Mesentery proper small intestinejejunum and ileum posterior abdominal wall superior mesenteric artery
dorsal mesentery * transverse mesocolon transverse colon posterior abdominal wall middle colic
dorsal mesentery * sigmoid mesocolon sigmoid colon pelvic wall sigmoid arteries
dorsal mesentery * mesoappendix mesentery of ileum appendix appendicular artery
OTHER LIGAMENTS AND FOLDS
ventral mesentery * falciform ligament liver thoracic diaphragm, anterior abdominal wall round ligament of liver, paraumbilical veins
left umbilical vein * round ligament of liver liver umbilicus
ventral mesentery * coronary ligament liver thoracic diaphragm
ductus venosus * ligamentum venosum liver liver
* phrenicocolic ligament left colic flexure thoracic diaphragm
ventral mesentery * left triangular ligament, right triangular ligament liver
* umbilical folds urinary bladder
* ileocecal fold ileum cecum
* broad ligament of the uterus uterus pelvic wall mesovarium, mesosalpinx, mesometrium
* ovarian ligament uterus inguinal canal
* suspensory ligament of the ovary ovary pelvic wall ovarian artery

In addition, in the pelvic cavity there are several structures that are usually named not for the peritoneum, but for the areas defined by the peritoneal folds:

Name Location Genders possessing structure
Rectovesical pouch between rectum and urinary bladder male only
Rectouterine pouch between rectum and uterus female only
Vesicouterine pouch between urinary bladder and uterus female only
Pararectal fossa surrounding rectum male and female
Paravesical fossa surrounding urinary bladder male and female

DevelopmentEdit

The peritoneum develops ultimately from the mesoderm of the trilaminar embryo. As the mesoderm differentiates, one region known as the lateral plate mesoderm splits to form two layers separated by an intraembryonic coelom. These two layers develop later into the visceral and parietal layers found in all serous cavities, including the peritoneum.

As an embryo develops, the various abdominal organs grow into the abdominal cavity from structures in the abdominal wall. In this process they become enveloped in a layer of peritoneum. The growing organs "take their blood vessels with them" from the abdominal wall, and these blood vessels become covered by peritoneum, forming a mesentery.

Clinical aspectsEdit

Peritoneal dialysisEdit

In one form of dialysis, the peritoneal dialysis, a glucose solution is run through a tube into the peritoneal cavity. The fluid is left there for a prescribed amount of time to absorb waste products, and then removed through the tube. The reason for this effect is the high number of arteries and veins in the peritoneal cavity. Through the mechanism of diffusion, waste products are removed from the blood.

Classification of abdominal structuresEdit

The structures in the abdomen are classified as intraperitoneal, retroperitoneal or infraperitoneal depending on whether they are covered with visceral peritoneum and whether they are attached by mesenteries (mensentery, mesocolon).

Intraperitoneal Retroperitoneal Infraperitoneal / Subperitoneal
Stomach, First part of the duodenum [5 cm], jejunum, ileum, Cecum, appendix, transverse colon, sigmoid colon, Rectum, upper 1/3 The rest of the duodenum, ascending colon, descending colon, Rectum (middle 1/3) Rectum (lower 1/3)
Liver, Spleen Pancreas
Kidneys, adrenal glands, proximal ureters, renal vessels Urinary bladder, distal ureters
In women: Uterus, Fallopian tubes, ovaries Gonadal blood vessels
Inferior vena cava, Aorta

Structures that are intraperitoneal are generally mobile, while those that are retroperitoneal are relatively fixed in their location.

Some structures, such as the kidneys, are "primarily retroperitoneal", while others such as the majority of the duodenum, are "secondarily retroperitoneal", meaning that structure developed intraperitoneally but lost its mesentery and thus became retroperitoneal.

EtymologyEdit

Peritoneum is derived from Greek via Latin. Peri- means around, while -ton- refers to stretching. Thus, peritoneum means stretched around or stretched over.

Additional imagesEdit

ReferencesEdit

  • Tortora, Gerard J., Anagnostakos, Reginald Merryweather, Nicholas P. (1984) Principles of Anatomy and Physiology, Harper & Row Publishers, New York ISBN 0-06-046656-1

External links Edit


This page uses Creative Commons Licensed content from Wikipedia (view authors).

Around Wikia's network

Random Wiki