25-01-23 - Peritoneum and peritoneal cavity Flashcards
Learning outcomes
- Describe the arrangement of the peritoneal cavity and “mesenteries”
- State the function of the peritoneum
- Describe the regions, spaces and recesses of the peritoneal cavity
- Describe peritoneal folds and ligaments and list their contents
- Describe the meaning of intraperitoneal and retroperitoneal
- Describe the nerve supply of the peritoneum and the concept of referred pain
- Discuss the clinical implications of the peritoneal cavity and its recesses
What is the peritoneum?
What do the visceral and parietal peritoneum line?
What forms the peritoneal cavity?
How do surgeons see the peritoneal cavity during endoscopic surgery?
How does the peritoneal cavity differ in men and women?
Why is this problematic for women?
How is the peritoneal cavity divided up?
What fluid is present in the peritoneal cavity?
What 3 structures does the peritoneum form?
- The peritoneum is a thin serous membrane
- Parietal peritoneum lines the walls of the abdominal & pelvic cavities
- Visceral peritoneum covers the viscera (organs)
- The potential space between the parietal & visceral peritoneum is called the peritoneal cavity
- To see the peritoneal cavity during endoscopic surgery, surgeons will inject air (normally CO2) because the peritoneal cavity is a potential space
- In males, the peritoneal cavity is a completely closed cavity
- In females, there is a potential, indirect communication with the exterior
- This can be problematic in women as infection can spread from the exterior to inside the peritoneal cavity in females
- The peritoneal cavity is divided into the greater and lesser sacs
- In the peritoneal cavity, there is lubricating peritoneal fluid secreted from the peritoneum that allows organs (viscera) to move and contract
- 3 structures the peritoneum forms:
1) Omenta (greater & lesser)
2) Mesenteries
3) Ligaments
How large is the peritoneal cavity?
What is the peritoneal divided into?
Where does the greater sac extend between?
Where does the lesser sac extend between?
What 2 medical procedures can the peritoneal cavity be used for?
What can spread in the peritoneal cavity?
- The peritoneal cavity is the largest cavity in the body
- It is divided into the greater sac and lesser sac (omental bursa)
- The greater sac is the main compartment extending from the diaphragm down into the pelvis
- The lesser sac lies posterior to the stomach & lesser omentum
- The peritoneal cavity can be used for peritoneal dialysis or fluid administration
- The peritoneal cavity can lead to the spread of infection, cells or bleeding
Where is the diaphragm located in the peritoneal cavity?
- The diaphragm is located at the superior wall and, partially, posterior walls of the peritoneal cavity
What is the phrenic the sole motor supply of?
What might occur is the phrenic nerve is severed?
What 3 things does the phrenic nerve supply sensory fibres to?
What is the supraclavicular nerve?
What does it supply?
How can this cause referred pain?
- The phrenic nerve is the sole motor supply of the diaphragm
- If the phrenic nerve is severed, the person can still live, but can’t exercise
- The phrenic nerve supplies sensory fibres to:
1) Mediastinal pleura
2) Peritoneum and pleura related to the central tendon of the diaphragm (sensory fibres don’t go to the periphery of the diaphragm)
3) Parietal pericardium - The supraclavicular nerve is made from nerve roots C3 and C4
- The supraclavicular nerve supplies the skin over the shoulder, which is the C4 dermatome
- This will mean structures with a sensory supply via the phrenic nerve may refer pain to the back of the neck, the supraclavicular region
What plexus is the phrenic nerve part of?
What ventral rami does it arise from?
What muscle does it sit over?
How does the phrenic nerve enter the mediastinum?
What structures does the phrenic nerve pass in the mediastinum?
Where does the right phrenic nerve go from here?
What does it innervate?
- The phrenic nerve is a branch of the cervical plexus
- It arises from the ventral (anterior) rami of C3, C4, C5
- The phrenic nerve goes over the scaleneus anterior muscle
- The phrenic nerve enters the mediastinum between the venous (subclavian vein) and arterial planes (subclavian artery)
- In the mediastinum of the thoracic cavity, the phrenic nerve passes anterior to the root of the lung, and lies between the fibrous pericardium and parietal pleura
- Right phrenic nerve
- The right phrenic nerve passes adjacent to the superior vena cava, then the inferior vena cava in the mediastinum
- It passes through the caval opening, which is an opening on the diaphragm that allows the right phrenic nerve to move into the abdominal cavity
- From here, it turns around and supplies the inferior surface of the diaphragm, which innervates the right hemidiaphragm
- Left phrenic nerve
- The left phrenic nerve crosses the aortic arch and goes over the left ventricle
- It travels between the pericardium and mediastinal pleura
- It descends towards the diaphragm but not into the abdominal cavity
- The left phrenic nerve is distributed on the superior surface of the hemidiaphragm, which innervates the left side of the diaphragm
What is the diaphragm?
What does it close?
What is its structure like at the periphery and centrally?
What does the diaphragm consist of?
How high is each dome compared to each other?
Where does the diaphragm sit on full expiration?
Where is it intersected by the ribs on full inspiration?
- The diaphragm is the musculotendinous structure that separates the thoracic cavity from the abdominal cavity
- It closes the inferior thoracic aperture
- The diaphragm is muscular at its periphery, but tendinous centrally at the central tendon
- The diaphragm consists of 2 domes/hemidiaphragms, with the right hemidiaphragm sitting about 1cm higher than the left
- The diaphragm sits at the 4th/5th intervertebral space at full expiration
- The intervertebral disc space is typically defined on an X-ray photograph as the space between adjacent vertebrae
- The diaphragm should be intersected by the 5th to 7th anterior ribs in the mid-clavicular line on full inspiration
What are crura of the diaphragm?
What is their role?
How many crura are there?
What do they form together?
What 6 things does the diaphragm attach to?
- The crus of diaphragm (pleural is crura), refers to one of two tendinous structures that extends below the diaphragm to the vertebral column.
- There is a right crus and a left crus, which together form a tether for muscular contraction.
- 6 things the diaphragm attaches to:
1) Xiphoid process of the sternum (attaches at vertebral level T8/9)
2) Deep surface of the last 6 ribs and costal cartilages (costal margin)
3) Lumbar vertebrae
* Left crus is located at (L1-2)
* Right crus is located at (L1-3)
4) Median arcuate ligament
* Located at the medial borders of the crura
5) Medial arcuate ligament
* Condensation of psoas fascia – covers psoas major muscle
* Medial arcuate ligament is attached to transverse process of L1 (or L2)
6) Lateral arcuate ligament
* Condensation of thoracolumbar fascia
* Lateral arcuate ligament is attached to transverse process of L1 – rib 12
Where does the diaphragm insert?
Where is the central tendon located?
What type of joint is the xiphisternal joint?
What sits on the central tendon?
What is the central tendon fused to?
What does this prevent during forced inspiration?
What does further contraction of the diaphragm pull?
- The diaphragm inserts on the central tendon (Centrum tendineum)
- The central tendon is at the level of xiphisternal synchondrosis joint (T9)
- The heart sits on the central tendon
- The central tendon is fused to the pericardium
- This prevents the pericardium’s descent during forced inspiration
- Further contraction of the diaphragmatic muscle pulls on ribs 7 to 10 from the anchored central tendon
What is the level of the caval opening?
What does it pass through?
What 2 structures pass through the caval opening?
What is the level of the oesophageal opening?
What 3 structures pass through the oesophageal opening?
- The caval opening is At T8 level, through central tendon
- 2 structures that pass through the caval opening:
1) Inferior vena cava
2) Right phrenic nerve - The oesophageal opening is at T10 level, through the right crus (sphincter)
- 3 structures that pass through the oesophageal opening:
1) Oesophagus
2) Both vagus nerves
3) Left gastric vessels (part of control centre of stomach)
What level is the aortic hiatus?
What does is pass behind?
What 3 structures pass through the aortic hiatus?
What level are the crura?
What 3 structures pass through the crura?
What is the level of attachment of the medial arcuate ligament?
What structure passes behind the medial arcuate ligament?
- The aortic hiatus is At T12 level and passes behind median arcuate ligament
- 3 structures pass through the aortic hiatus:
1) Aorta
2) Thoracic duct
3) Azygos and Hemiazygos (±) - Left crus is at level L1-2
- Right crus is at level L1-3
- 3 structures pass through the crura:
1) Branches of left phrenic nerve
2) Splanchnic nerves
3) Azygos and Hemiazygos (±) - The medial arcuate ligament is attached to transverse process of L1 (or L2)
- The sympathetic trunk passes behind the medial arcuate ligament
What are the 4 different arterial supplies of the diaphragm?
- 4 different arterial supplies of the diaphragm:
1) Superior phrenic arteries
* Branch of thoracic aorta
2) Branches of musculophrenic arteries
* Supplies some of the anterior intercostal arteries
3) Branches of pericardiacophrenic arteries
4 Inferior phrenic artery
* Branch of abdominal aorta
What is the lesser sac?
Where is it located?
How does the lesser sac communicate with the greater sac?
- The lesser sac is part of the peritoneal cavity that lies posterior to the stomach & lesser omentum
- The lesser sac communicates with the greater sac via the epiploic foramen
What is the lesser omentum embryologically derived from?
What structures does it pass between?
What 2 structures can the lesser omentum be subdivided into?
What structures do they each run between?
What does the hapetoduodenal ligament form?
What 3 structures does the lesser omentum contain?
What can also be considered the portal triad?
- The lesser omentum is embryologically derived from the ventral mesentery anterior to the gut tube
- The lesser omentum passes from the lesser curvature of the stomach & 1st part of duodenum to the inferior border of the liver
- 2 structures can the lesser omentum be subdivided into:
1) Hepatogastric ligaments
* Loose membrane structure
* Runs from the greater curvature of the stomach to the liver
2) Hepatoduodenal ligaments
* Runs from the 1st part of the duodenum to the liver
* The hepatoduodenal ligament is the free edge of the lesser omentum
- The lesser omentum contains the portal triad (3 structures):
1) Hepatic portal vein
2) Hepatic artery proper
3) Common bile duct - The hepatic lobules each contain branches of the portal triad, and so may also be referred to as portal triads
What is the epigloic (omental) foramen a connection between?
What is another name for it?
What are the 4 boundaries of the epigloic foramen?
- The epigloic (omental) foramen is a connection between the greater and lesser sacs (divisions of the peritoneal cavity)
- Another name for it is the Foramen of Winslow
- 4 boundaries of the epigloic foramen:
1) Anterior boundary – hepatoduodenal ligament
2) Posterior boundary – IVC
3) Superior boundary – Caudate process of caudate lobe of liver
4) Inferior border – First part of duodenum
How can the lesser sac be approached during surgery?
Why is this done?
What is the name for this manoeuvre?
- During surgery the lesser sac may be approached via the epiploic foramen
- During surgery, the hepatic artery proper & portal vein can be compressed with fingers/haemostat to control bleeding while structures are being fixed
- This is known as Pringle’s manoeuvre
What is the greater omentum derived from?
What is the greater omentum attached to?
What structure might it fuse with?
What does the greater omentum consist of?
What structures does it lie over?
What structures does the greater omentum contain?
- The greater omentum is derived from the dorsal mesentery (posterior to the gut tube), which is derived from 2 layers of peritoneum
- The greater omentum is attached to the greater curvature of the stomach & 1st part of duodenum
- The greater omentum may fuse with the transverse colon, as it hangs like an apron anterior to the small intestine
- The greater omentum Consists of a double layer of visceral peritoneum folded upon itself
- It overlies the transverse colon & much of the small intestine
- The greater omentum contains fat and gastro-epiploic arteries (supply the stomach), which can found between the 2 layers of the greater omentum
What edges of the greater omentum are attached/free?
Why can the greater omentum be referred to as “Policeman of the Abdomen”?
- The greater omentum is attached superiorly, but the inferior and lateral borders are free
- Why the greater omentum can be referred to as “Policeman of the Abdomen”:
- When there is an infection in the peritoneal cavity, the greater omentum will move towards it to try and contain it e.g appendicitis will cause the greater omentum to rap around the appendix
- A mass called by the greater omentum is called a plastron
What is mesentery?
What is it formed by?
What are the roles mesenteries?
What can also fill this role?
How are mesentery/mesos formed in embryology?
What are the exceptions?
What is mesentery of the small intestine referred to as?
What are mesenteries of other abdominal regions referred to as?
- Mesentery is tissue formed by a double layer of visceral peritoneum
- The role of mesenteries it to attach the abdominal organs to the posterior abdominal wall and also serve as a passage for blood vessels, nerves & lymphatics to go into organs
- Other organs can also be attached to the posterior abdominal wall by peritoneum – these are technically mesenteries but are not referred to as such
- Mesentery/mesos are derived from dorsal mesentery of the embryo, which is posterior to the gut tube
- Exceptions to this are the falciform ligament of the liver (connects liver to posterior abdominal wall)
- Mesentery of the small intestine is known as “the mesentery”
- Mesenteries of other abdominal regions should be named according to the corresponding organ (mesocolon, mesoappendix, mesometrium)
What is the mesentery?
What organs does it connect to the posterior abdominal wall?
Where does the mesentery start and end?
How long is the base?
What 5 structures does the mesentery cross?
What 3 structures can be found within the mesentery?
- The mesentery is a fan shaped double layered fold of visceral peritoneum
- The mesentery connects the jejunum & ileum to the posterior abdominal wall
- Its base starts just left of L2 & passes obliquely downwards to the right ending just above the right sacroiliac joint
- The base is approximately 20 cm long
- structures the mesentery crosses:
1) 3rd part of the duodenum
2) Aorta
3) Inferior vena cava
4) Right gonadal vessels
5) Right ureter - 3 structures can be found within the mesentery:
1) Superior mesenteric vessels
2) Nerves
3) Lymphatics
What is the transverse mesocolon?
What is its role?
Where is its route located?
What structures does the transverse mesocolon carry?
What 3 structures does the transverse mesocolon cross?
- The transverse mesocolon is the mesentery of the transverse colon
- Its role is to suspend the transverse colon from the posterior abdominal wall
- Its root is just inferior to the pancreas
- The transverse mesocolon carries branches of the middle colic vessels, which is the first branch of the superior mesenteric artery and supplies the mesocolon
- 3 structures the transverse mesocolon crosses:
1) Aorta
2) IVC
3) 2nd part of duodenum
What is the sigmoid mesocolon?
What shape is it?
What is it formed by?
What is its role?
Where is the sigmoid mesocolons root?
What 2 structures does the sigmoid mesocolon cross?
What 3 structures does the sigmoid mesocolon transmit?
- The sigmoid mesocolon is the mesentery of the sigmoid colon
- Like the sigmoid colon, the sigmoid mesocolon is s-shaped
- It is a Double-layered fold of visceral peritoneum
- The sigmoid mesocolon connects the sigmoid colon to the posterior abdominal wall
- Its root is in the left iliac fossa
- 2 structures the sigmoid mesocolon crosses:
1) The bifurcation of the left common iliac vessels
2) Left ureter - 3 structures the sigmoid mesocolon transmits:
1) Sigmoid branches of the inferior mesenteric vessels
2) Nerves
3) Lymphatics
How does the transverse mesocolon divide the peritoneal cavity (greater sac)?
What 5 structures does the supracolic compartment contain?
What 5 structures does the infracolic compartment contain?
How do the supracolic and infracolic compartments communicated (connect)?
Where can these structures be found?
- The transverse mesocolon divides the peritoneal cavity (greater sac) into the supracolic & infracolic compartments
- 5 structures the supracolic compartment contains:
1) Duodenum
2) Liver
3) Gallbladder
4) Stomach
5) Spleen - 5 structures does the infracolic compartment contain:
1) Duodenum
2) Jejunum
3) Ileum
4) Ascending colon
5) Descending colon - The supracolic and the infracolic compartments communicate (connect) with each other through the paracolic gutters
- Paracolic gutters can be found on the lateral sides of the ascending and descending colon between the colon and the posterior abdominal wall
What do peritoneal reflections create?
What are the purpose of these structures?
What are paracolic gutters?
Where are they located?
What do they allow for?
Where will fluid in the peritoneal cavity when a patient is supine?
Where will peritoneal fluid go in the peritoneal cavity when a patient is semi-recumbent?
Where will a large excess of fluid in the peritoneal cavity go?
- Peritoneal reflections create important recesses, spaces and gutters
- These structures can be the sites for the collection and movement of peritoneal fluid
- Paracolic gutters are grooves between the lateral aspects of the ascending or descending colon and the posterolateral abdominal wall
- There is free communication between the supracolic and the infracolic compartments through the paracolic gutters
- When a patient is supine (lying flat on back), fluid in the peritoneal cavity will go through paracolic gutters into the left and right posterior subphrenic spaces and the pelvic cavity
- When a patient is semi-recumbent (half sitting up), fluid in the peritoneal cavity will flow down into the pelvic cavity
- If there is a large excess of fluid (about 2 litres) in the peritoneal cavity, the fluid can go through the paracolic gutters and enter the left and right anterior subphrenic space
What is another name for the hepatorenal recess?
What part of the peritoneal cavity is the hepatorenal recess?
Where is the subphrenic recess located?
How is it divided?
How are both these recesses linked?
Where will excess fluid accumulate first in the peritoneal cavity if the patient is supine?
- The hepatorenal recess is also known as the right posterior subhepatic space or Morison’s pouch
- The hepatorenal recess is the part of the peritoneal cavity on the right side between the liver and the right kidney and right suprarenal gland (only present on the right side)
- The subphrenic space/recess is between the diaphragm and the liver
- The subphrenic space is divided by the falciform ligament
- The subphrenic and hepatorenal recesses are continuous anteriorly
- If the patient is supine, excess fluid (e.g from haemorrhage) will first accumulate in the hepatorenal recess
What are the deepest parts of the abdomino-pelvic cavity in men and women?
What do they each separate?
How are each of these structures formed?
What does the rectouterine pouch separate in females?
Where will fluid in the peritoneal cavity accumulate when the patient is upright?
- Rectovesical (men) and rectouterine (women) pouches are the deepest parts of the abdominopelvic cavity
- The Rectovesical pouch in males separates the rectum from the urinary bladder
- The rectovesical pouch is formed by peritoneum covering the posterior abdominal wall, then part of the rectum, then reflecting on itself and covering the superior wall of the bladder
- The Rectouterine pouch (of Douglas) in females separates the rectum from the uterus
- The rectouterine pouch if formed by peritoneum covering the posterior abdominal wall, then the rectum, then reflecting on itself and covering the uterus
- The vesicouterine pouch in females separates the urinary bladder from the uterus
- When a patient is upright, fluid in the peritoneal cavity will accumulate in the rectovesical pouch in men and the rectouterine pouch in females
What is a peritoneal fold?
Where are they often formed?
What are the 5 folds peritoneal on the posterior abdominal wall?
What are they each formed by?
What are peritoneal ligaments?
What is their purpose?
- A peritoneal fold is a reflection of peritoneum
- Often formed by peritoneum covering blood vessels, ducts or obliterated foetal vessels
- 5 peritoneal folds on the posterior abdominal wall:
1) The median umbilical fold
* remnant of the urachus that extends from the urinary bladder to the umbilicus
* The urachus is obliterated when we are born and forms the medial umbilical fold
2) 2 medial umbilical folds
* Overlie remnants of the umbilical arteries
* Runs from the internal iliac artery to the umbilicus, and then from the umbilicus to the placenta
3) The 2 lateral umbilical folds
* Formed by and contains the inferior epigastric arteries
- Peritoneal ligaments are two-layered folds of peritoneum that connect 2 organs together
What exists between the peritoneal folds?
What are the 3 fossae that exist between the peritoneal folds?
- Between the folds and lateral to the lateral umbilical fold, there are depressed areas
- 3 fossae that exist between the peritoneal folds:
1) Supravesical fossae
* Between the median and medial umbilical folds
* 2 of these fossae
2) Medial inguinal fossae (also called Hesselbach’s triangle)
* Weak area
* Between medial and lateral folds
* Where direct inguinal hernias can form
3) Lateral inguinal fossae (Deep inguinal ring)
* Lateral to lateral umbilical folds
* Where the deep inguinal ring is found
* Where indirect inguinal hernias occur
What are intraperitoneal, primary retroperitoneal and secondary retroperitoneal viscera?
Name the 8 intraperitoneal viscera.
Name the 7 Primary Retroperitoneal viscera.
Name 3 Secondary retroperitoneal viscera.
- When organs press against the peritoneum, they become intraperitoneal or retroperitoneal (aka extraperitoneal)
1) Intraperitoneal viscera:
* Almost totally covered with visceral peritoneum
* Suspended by a mesentery attached to the posterior abdominal wall
- 8 Intraperitoneal viscera:
1) Stomach
2) Spleen
3) Liver
4) First part of the duodenum
5) Jejunum
6) Ileum
7) Transverse colon
8) sigmoid colon
1) Primary Retroperitoneal
* Lie behind or outside the peritoneum
* Only partially covered with visceral peritoneum (on 1 surface)
* E.g aorta developed outside of the peritoneum and stayed there
- 7 Primary Retroperitoneal viscera:
1) Adrenal glands
2) Kidneys
3) Ureter
4) Abdominal aorta
5) Inferior vena cava and their branches
6) Rectum (superior 1/3 intraperitoneal middle 1/3 partially intraperitoneal, with lower 1/3 totally extraperitoneal)
7) Bladder
2) Secondary retroperitoneal
* Initially intraperitoneal but migrate retroperitoneally during embryogenesis & lose their mesentery
- 3 Secondary retroperitoneal viscera:
1) Pancreas (except its tail)
2) Ascending colon
3) Descending colon
4) Duodenum (except first part)
What is the nervous supply to the visceral peritoneum?
What 2 things is the visceral peritoneum sensitive to?
What 3 things is it not sensitive to?
How does this affect the localisation of pain?
Where is pain from visceral peritoneum referred to (in picture)
- The visceral peritoneum is supplied by autonomic afferent nerves that also supply the viscera
- The visceral peritoneum is sensitive only to:
1) Stretch
2) Tearing (which causes diffuse & poorly localised pain) but not to touch, pressure or temperature - The visceral peritoneum is not sensitive to:
1) Touch
2) Pressure
3) Temperature - The brain cannot localise visceral pain & this is often referred to a dermatome
- Where pain from visceral peritoneum is referred to (in picture)
