Peritoneum, Peritoneal Cavity, and Mesenteries Lecture (Test 1) Flashcards
Organization of GI Tract
1) Foregut
2) Midgut
3) Hindgut
Foregut
Organs:
1) Stomach
2) Liver
3) Gallbladder
4) Pancreas
5) Spleen
6) First half of Duodenum
Arteries:
1) Celiac Trunk
- Ileocolic
- Right Colic
- Middle Colic
Motor Nerve Supply:
- Vagus Nerve
Midgut
Organs:
1) 2nd Half of Duodenum
2) Jejunum and Ileum
3) Cecum
4) Ascending Colon
5) 2/3 Transverse Colon
Arteries:
1) Superior Mesenteric Artery
- Ileocolic
- Right Colic
- Middle Colic
Motor Nerve Supply:
- Vagus Nerve
Hindgut
Organs:
1) Left 1/3 of Transverse Colon
2) Descending Colon
3) Sigmoid Colon
4) Rectum
Arteries:
1) Inferior Mesenteric Artery
- Left Colic
- Sigmoid Branches
- Superior Rectal
Motor Nerve Supply:
- Pelvic Splanchnic Nerves
Peritoneum (General)
- A Serous Membrane
Subdivisions (Think Pleura or Pericardium)
1) Parietal Layer:
- Lines the Body Wall
- Has abundant PAIN FIBERS via nerves from the Body Wall
2) Visceral Layers (Serosa)
- Covers Viscera
- LACKS pain fibers
Nerve Supply to the Parietal Peritoneum
A) Nerves from the adjacent body wall supply Parietal Peritoneum
B) Supply PAIN and VASOMOTOR FIBERS
C) Conduct Sharp, Stabbing pain
- Rigid Abdomen
- Abdominal Rigidity is a stiffness of your stomach muscles that occur when the abdomen is touched
- This is an Involuntary response to prevent pain caused by pressure on your abdomen
- Another term for this protective mechanism is “guarding”
Visceral Peritoneum
- Invests Viscera/ Organs
- Same Blood Supply Lymphatic Vasculature and Visceral Nerve Supply as the Organs it covers
- Insensitive to Touch, Heat, Cold, Laceration
- Sensitive to Stretching and Chemical Irritation
- Pain from Visceral Peritoneum is POORLY LOCALIZED, ex Referred Pain
a) Unmyelinated C-fibers
b) Crampy, Colicky pain
General Relations of Viscera to Peritoneum
A) Intraperitoneal Organs
- Covered on most sides by Visceral Peritoneum
- Suspended by MESENTERY from the Body Wall
B) Retroperitoneal Organs
- Lie deep to the Parietal Peritoneum
- Covered by Parietal Peritoneum on ONE SIDE ONLY!!
Intraperitoneal Organs
- Stomach
- Small Intestine (Jeujenum, Ileum, some of the Superior part of the Duodenum)
- Spleen
- Liver
- Gallbladder
- Cecum with Vermiform Appendix (Portions of Variable size may be RETROPERITONEAL)
- Large Intestine (Transverse and Sigmoid Colon)
Retroperitoneal Organs
PRIMARILY (Never had a Mesentery):
- Kidneys
- Suprarenal Glands
- Uterine Cervix
SECONDARILY (Lost the Mesentery):
- Duodenum (Descending, Horizontal, and Ascending)
- Pancreas
- Ascending and Descending Colon
- Rectum (Upper 2/3)
Peritoneal Reflections (Adult)
- Mesenteries
- 2 layers fold of the Peritoneum
The Mesentery:
- Attaches the “Free” Small Intestine to the POSTERIOR BODY WALL
- Jejunum
- Ileum
Developmentally for the Mesentery
- Dorsal Mesentery
- Ventral Mesentery
a) Mesentery attached to the Stomach = MESOGASTRIUM - DORSAL AORTA and its 3 Branches run through the Dorsal Mesentery
- VENTRAL MESENTERY only Extends from the Respiratory Diaphragm to the Duodenum
Peritoneal Reflections (Adult)
Subdivisions of Mesentery:
1) TRANSVERSE MESOCOLON:
- Mesentery of the Transverse Colon
- Holds the Transverse Colon to the Posterior Body Wall
- Fuses with he Posterior Layer of the Greater Omentum
2) SIGMOID MESOCOLON:
- Mesentery of the Sigmoid Colon
- Holds the Sigmoid Colon to the Posterior Body Wall
3) MESOAPPENDIX
- Mesentery of the Vermiform Appendix
Note: The Mesenteries of the Duodenum, Ascending Colon, Descending Colon and Cecum are usually lost during development. Since they are no longer suspended by a Mesentery, these Organs are SECONDARILY RETROPERITONEAL
Peritoneal Ligaments
- May be Subdivisions of a Larger Structure
- Usually transmit Nerves ad Vessels
- Usually lack Connective Tissue and are NOT the same as Ligaments that Join Bones
1) GASTROSPLENIC Ligament
2) SPLENORENAL (Ileorenal) Ligament
Peritoneal Reflections (Adult)
- Omentum (Epiploon)
- Borad, 2-layered sheet of Peritoneum that attaches the Stomach to other Viscera
- Lesser Omentum (Connects liver to Stomach and Duodenum)
a) Develops from VENTRAL MESOGASTRIUM (Mesentery)
b) Subdivided into parts
1) HEPATOGASTRIC Ligament (Stomach to Liver)
2) HEPATODUODENAL Ligament (Liver to Duodenum)
Lesser Omentum
- Composed of two Ligaments:
1) HEPATOGASTRIC Ligament
2) HEPATODUODENAL Ligaments
- Contains Heportal Triad:
a) Hepatic Portal Vein
b) Common Bile Duct
c) Hepatic Artery
- Develops from VENTRAL MESOGASTRIUM
Peritoneal Reflections (Adult)
Greater Omentum
- Develops from the DORSAL MESOGASTRIUM
- GASTROCOLIC Ligament (Stomach to Transverse Colon)
- GASTROPHRENIC Ligament (Stomach to Diaphragm, and is continuous with Phrenicosplenic Ligament)
- GASTROSPLENIC Ligament
Ligaments associated with the Liver
1) Coronary Ligaments
2) Right and Left Triangular Ligaments
3) Falciform Ligament
- Ligamentum Teres Hepatis
Clinical Note: The Diaphragm is directly connected to the Liver therefore it is easy for the Cancer to Metastasize from either the Lungs down or the Abdomen up
“Minor” Folds and Fossae
1) FOLDS:
- A Ridge or Elevation in the Peritoneum produced by underlying Vessels
2) FOSSAE (Fossa) or Recesses:
- Are depressions between Folds
a) SUPERIOR DUODENAL Fold and Fossa (Recess)
b) PARADUODENAL Fossa
c) INFERIOR DUODENAL Fold and Fossa
d) RETRODUODENAL Fossa
e) Fold is formed by Inferior Mesenteric Vein POSTERIOR to Peritoneum
Fools and Fossae of the Internal Aspect of the Abdominal Wall
- Structures coursing through the Exprateriotoneal Tissue form ELEVATIONS on the Interior Abdominal Wall called PERITONEAL (Umbilical Folds)
1) MEDIAN UMBILICAL FOLD:
- Urachus
- Midline from bladder
2) MEDIAL UMBILICAL FOLDS (2):
- Medial Umbilical Ligaments
- Obliterated UMBILICAL ARTERY
3) LATERAL UMBILICAL FOLDS (2):
- INFERIOR EPIGASTRIC Vessels
- Function Arteries and Veins
Supra umbilical Structures on Anterior Abdominal Wall
- Supraumbilical Structures located on the Internal aspect of the Anterior Abdominal Wall:
1) FALCIFORM LIGAMENT - Curved remnant of the Ventral Mesogastrium
- LIGAMENTUM TERES HEPATIS (Round Ligament of the Liver) in its lower Free Border
- OBLITERATED UMBILICAL VEIN
Peritoneal Fossae
1) SUPRAVESICAL FOSSA:
- Between the Median and Medial Umbilical folds
- Site for Supravesical Hernias (Rare)
2) MEDIAL INGUINAL FOSSA:
- Between the Medial and Lateral Umbilical Folds
- Site for DIRECT INGUINAL HERNIAS
- Also called Inguinal Triangle
3) LATERAL INGUINAL FOSSA:
- Lateral to the Lateral Umbilical folds
- Site for INDIRECT INGUINAL HERNIAS
Greater Sac of the Peritoneal Cavity
- The Greater Sac is most of the “potential” space within the Abdomen
- It can be subdivided into SUPRACOLIC and INFRACOLIC Regions by the Colon and Transverse Mesocolon
SUPRAMESOCOLIC (Supracolic) Region:
- Superior and Anterior to the Liver and Stomach
- Includes Hepatorenal and Subphrenic Spaces and Fossae of the Anterior Wall
Greater Sac of the Peritoneal Cavity Cont
- The Peritoneal Cavity is “Closed” Potential Space between Parietal and Visceral Layers of PERITONEUM
- Recesses and Fossae of the Peritoneal Cavity
a) Subphrenic Recess
b) Subhepatic/ Hepatorenal Recess
c) Rectovesical/ Rectouterine Recess
***Clinically important because ABSCESSES may develop and EXCESS FLUID (Ascites) will pool here!!!!!
Greater Sac of the Peritoneal Cavity Cont
INFRAMESOCOLIC (Infracolic) Region
INFRAMESOCOLIC Region:
- Inferior and Posterior part of the Greater Sac
- Subdivided by Mesenteries and “Ligaments”
- Right and Left PARABOLIC Gutters are Lateral to the Ascending and Descending Colon
- Upper and Lower parts are divided by THE MESENTERY into Right and Left Infracolic Spaces
- Clinically important spaces where Intraperitoneal Infections spread
- The PHRENJICOCOLIC Ligament limits the spread of FLUID SUPERIORLY
Lesser Sac of the Peritoneal Cavity
- Lesse Sac (Mental Bursa) develops sas part of the Greater Sac
a) The Lesser sac is Posterior and Inferior to the Stomach
b) Greater and Lesser Peritoneal Sacs communicate through the EPIPLOIC FORAMEN (of Winslow) - Recesses of the Lesser Sac
a) SUPERIOR RECESS: Posterior to the Liver
b) INFERIOR RECESS: Potential Space between the 2 layers of the Gastrocolic Ligament
c) SPLENIC RECESS: Posterior to and Left of the Stomach
- Clinically important Relationship to the Liver, Pancreas, Stomach and Spleen
Lesser Sac of the Peritoneal Cavity Cont
EPIPLOIC FORAMEN (of Winslow) (Omental Foramen)
Epiploic Foramen:
- The opening between the Greater and Lesser Sacs
- Anterior: Hepatoduodenal Ligament with the Portal Vein, Hepatic Artery and Bile duct
- Posterior: IVC, Diaphragm
- Superior: Liver, Caudate Lobe
- Inferior : Duodenum, 1 st part
