The peritoneum lines the abdominal cavity and comprises two layers. The mesentery suspends portions of the bowel and contains blood vessels, lymph nodes, and nerves. The peritoneal spaces include the lesser sac, supracolic and infracolic compartments. During development, the peritoneum and mesentery arise from the trilaminar embryo. Diseases can spread within the peritoneal cavity along ligaments, mesenteries, and lymphatics. The omentum, mesentery, and peritoneal recesses have clinical relevance for surgery and disease spread.

1. SURGICAL ANATOMY OF
PERITONEUM,MESENTERY AND
RETROPERITONEUM
DR.MEENAL
DEPT OF GENERAL SURGERY

2. INTRODUCTION
PERITONEUM
• Serous membrane lining the abdominal cavity.
• Comprises of 2 layers i.e. parietal peritoneum and
visceral peritoneum.
• Surface area is 1.0 to 1.7 mt sq.
• In males, the peritoneal cavity is sealed.
• In females, it is open to the exterior through the ostia of
the fallopian tubes.

4.  MESENTERY
• Fan shaped double layer of peritoneum that suspends the
small and large bowel from the posterior abdominal wall.
• Conduit for neurovascular and lymphatic structures between
the organ and retroperitoneal structures.

5. BLOOD SUPPLY

6. INNERVATION
• The superior mesenteric plexus (a continuation of the
celiac plexus) accompanies the superior mesenteric
artery into the mesentery.
• The superior mesenteric plexus then divides into many
secondary plexuses which
contain parasympathetic and sympathetic
innervation to the mesentery associated with a particular
organ, the organs themselves and their related blood
vessels.

7. LYMPHATICS
• The mesentery contains both lymph nodes and lymphatic
vessels. There are several groups of lymph nodes found
within the mesentery:
• Inferior mesenteric lymph nodes – receives lymph from
the hindgut organs, and drains into the superior
mesenteric lymph nodes.
• Superior mesenteric lymph nodes – receives lymph
from the midgut organs (and from the inferior mesenteric
nodes), and drains into the pre-aortic lymph nodes.

9.  Ligament
• A peritoneal ligament is a double fold of peritoneum that
connects viscera together or connects viscera to the abdominal
wall.
• Named according to the structures it connects.

10.  Omentum
• Double-layered continuation of peritoneal ligaments joining the
stomach and proximal duodenum to adjacent structures.

11. EMBRYOLOGICAL DEVELOPMENT OF
PERITONEUM & MESENTERY
• It starts developing during the
gastrulation process alongside
the primitive gut .
• It ultimately develops from the
mesoderm of the trilaminar
embryo.
• Within this body cavity , the
primitive gut tube is formed.

12. • The layer covering the gut is later known as the visceral
peritoneum.
• One covering the wall is known as the parietal
peritoneum.
• Primitive foregut separates upper part of the body cavity
into right & left body cavities by the virtue of its dorsal and
ventral mesentries.

13. • Rotation of the foregut
occurs separately from
the midgut and the
hindgut.
• Gives rise to the liver in
the ventral mesentery
and the spleen within the
dorsal mesentery.
• Rotation occurs 90
degrees to the stomach
such that ventral
mesentery comes to lie
to the right and dorsal
mesentery to the left.
LATERAL VIEW OF
THE PRIMITIVE GUT
TUBE

15. • In the region of the stomach it forms- dorsal
mesogastrium or greater omentum.
Region of duodenum -dorsal mesoduodenum
Region of colon-mesocolon
Dorsal mesentery of jejunal and ileal loops-mesentery
proper.

16. • Ventral mesentery, which exists only in the region of the
terminal part of the esophagus, the stomach, and the upper part
of the duodenum is derived from the septum transversum.
• Growth of the liver into the mesenchyme of the septum
transversum divides the ventral mesentery into:
i. the lesser omentum,
ii. the falciform ligament

18. PERITONEAL SPACES
 Peritoneal cavity is divided into interconnecting spaces by the
transverse colon and its mesentery which connects the colon to
the posterior abdominal wall:
• Supramesocolic
• Inframesocolic

19. CORONAL VIEW

20. SUPRAMESOCOLIC COMPARTMENT
 RIGHT
• Subphrenic space
• Subhepatic space
• Lesser sac
 LEFT
• Perihepatic space
• Subphrenic space
•
PARASAGITTAL SECTION

21.  Right suprahepatic/subphrenic space
• Space opens into the general peritoneal cavity
anteriorly and inferiorly.

22.  Right subhepatic space:
• Anterior
• Posterior ,also known as the hepatorenal fossa or Morrisons
pouch.

23.  LESSER SAC
• Extends behind the stomach, anterior to the pancreas.
• Communicates with the rest of peritoneal cavity through a
narrow inlet, the epiploic foramen (foramen of Winslow).
• Short , vertical slit, about 3cm in height in adults.

25. THE LESSER OMENTUM REMOVED TO SHOW
THE EPIPLOIC FORAMEN OF WINSLOW.

26. CLINICAL RELEVANCE
A posterior gastric ulcer may
perforate into the lesser sac.
• Gastric content and pus
accumulates in the lesser sac,
forming an abcess.
• Through foramen of Winslow this
passes into the peritoneal cavity,
leading to generalized peritonitis.

27.  Usually a loop of small
intestine can pass through the
epiploic foramen and become
twisted and strangulated in
the lesser sac.
• Pre-disposing factors include:
i. Large epiploic foramen
ii. Reduntant or mobile
mesentery
iii. Elongated right liver
iv. Defect in the lesser
omentum.

28. SURGICALAPPROACH OF THE
LESSER SAC
 During minimally invasive upper GI surgery, it can
be approached in 3 ways:
i. By opening the hepatogastric ligament (pars
flaccida of the lesser omentum)
ii. Through the gastrocolic and gastrosplenic
ligament, and;
iii. By opening the transverse mesocolon at the level
of the pancreas.

29. • First two approaches are used in upper GI
surgery, being the approach through the
gastrosplenic ligament used to create any type of
fundoplication during surgery for GERD.
• The last option is used in colorectal surgery for
mobilization of the splenic flexure.

30. INTRA-ABDOMINAL STRUCTURES OF
LESSER SAC

31.  LEFT SUPRAMESOCOLIC SPACE
• Four arbitrary communicating subspaces
i. Left anterior perihepatic space
ii. Left posterior perihepatic space
iii. Left anterior subphrenic space
iv. Posterior subphrenic(perisplenic) space
PARASAGITTAL SECTION
THROUGH THE TRUNK

32. SAGITTAL SECTION THROUGH THE LEFT
LOBE OF THE LIVER AND LESSER SAC

33. CLINICAL RELEVANCE:SUBPHRENIC
ABCESSES
• Refer to accumulation of pus in the right or left
subphrenic space.
• More common on the right side due to the increased
frequency of appendicitis and ruptured duodenal ulcers
(pus from the appendix can track up to the subphrenic
space via the right paracolic gutter).

34. RELATIONS OF AN ABCESS IN THE ANTERIOR
AND POSTERIOR PORTION OF RIGHT
SUBPHRENIC SPACE

35. • Phrenicocolic ligament forms a partial barrier to the spread of
fluid from left paracolic gutter into the left subphrenic space
hence left subphrenic collections are less common than right
sided.

36.  SURGICAL CONSIDERATIONS
• Drain a right anterior subphrenic abcess using a small right
subcostal incision to establish an extraperitoneal route.
• Posteriorly, the approach must be by an incision at the level of
the spinous process of L1. This avoids the pleura.
• The pleura and the 12th rib are related at the vertebral
spine thus care should be taken to avoid traversing the
bed of the 12th rib.

37. INFRAMESOCOLIC SPACE
 Is divided into 2 unequal spaces by the root of the small
bowel mesentery running from the DJ flexure in the left
upper quadrant to the ileocaecal valve in the right lower
quadrant:
• The smaller right infracolic space
• The larger left infracolic space

38. PARACOLIC SPACES
• Located lateral to the peritoneal reflections of the left and
right sides of the colon.
• Right is larger than the left and communicates freely with
the right subphrenic space.
• The connection between the left paracolic gutter an
subphrenic space is partially limited by the phrenicocolic
ligament.
• Both the right and left paracolic gutters communicate with
the pelvic space.

40. PELVIC SPACES
• Inferiorly the peritoneum is reflected over the fundus of
the bladder , the anterior & posterior surface of the uterus
in females, and on to the superior part of the rectum.
• Divided into the right & left paravesical spaces by the
urinary bladder.

41. PERITONEAL REFLECTIONS

42. GREATER OMENTUM
• Can be divided into 2 parts from a surgical point of view:
i. An upper part , the gastrocolic ligament
ii. Lower part the true greater omentum or fat apron
• Formed by 4 peritoneal layers, 2 anterior and 2 posterior-
fuse together during development & growth.

43. BLOOD SUPPLY OF GREATER
OMENTUM

44. SURGICAL APPLICATIONS
• The two-layer gastrocolic ligament, is the best pathway
for lesser sac exploration, especially closer to the greater
curvature.
• All the 6 layers of gastrocolic ligament are fused and the
middle colic artery as well as the other omental vessels
may be the cause of complications.

45.  For mobilization of the right side of the omentum:
• transect the gastrocolic ligament inferior to the right
gastroepiploic artery.
• ligate the anterior epiploics or the right gastroepiploic
artery distal to the origin of the right epiploic vessels.
 For mobilization of left side:
• ligate only the gastric branches of the left gastroepiploic
arches.
• do not ligate the left epiploic arteries

46.  LESSER OMENTUM
• Posterior component of the ventral mesentery.

47. CONTENTS

48. SURGICAL CONSIDERATIONS
 Falciform ligament
• Cut should be made between proximal and distal ligations
to avoid bleeding from a patent round ligament.
 Hepatogastric ligament
• Routinely divided during mobilization of the liver or
stomach.
• Care must be taken to preserve a dominant left hepatic
artery that travels through the ligament if a right hepatic
lobectomy, or if the patient has had prior interruption of
the right hepatic artery.

49.  GASTROSPLENIC LIGAMENT
• Extends from the posterolateral wall of the fundus and greater
curvature of the stomach to the splenic hilum.
• Continuous with the gastrocolic ligament.
• Short gastric arteries, veins and lymph nodes in the upper part.
• Left GE artery and vein, terminal branches of the splenic artery
and lymph nodes in the lower part.
• It’s a frequent route for sub-peritoneal spread of pancreatitis
related fluid.

50.  TRANSVERSE MESOCOLON
• Suspends the transverse colon in the abdominal
cavity.
• Diseases of the pancreas, such as pancreatic
cancer & acute pancreatitis, can spread via the
subperitoneal route along the transverse
mesocolon anteriorly to the colon, the gastrocolic
ligament, and the omentum.
• Colonic involvement is caused by direct spread
of pancreatic enzymes through the
extraperitoneal fat planes along the mesocolon,
causing pericolitis.

51.  SMALL BOWEL MESENTERY
• Voluminous, fat laden peritoneal reflection.
• Suspends the ileal & jejunal loops in the abdomen.
• Short base which is continuous with the right mesocolon.
• Root of the mesentery is approximately 15cm.
• It’s root is a bare area continuous with the anterior pararenal
space of the retroperitoneum.
• The root also contains 2 major blood vessels, the superior
mesenteric artery and the superior mesenteric vein.

52. • One of the most likely structure to be involved in metastatic
disease.
• Inflammation and tumour may involve the mesentery directly
e.g,from the pancreatic body or jejunum or by way of
neurovascular plexus or lymphatic channels that run within it.
• Rarely rotational and fusion anomalies of the mesentery may
lead to volvulus or internal hernia.
• Fat necrosis due to pancreatitis and occasionally pancreatic
cancer spread subperitoneally into the small bowel mesentery.
SIGMOID MESOCOLON
• Most common pathologic process involving this structure is
acute diverticulitis.

53. LATERAL RELATIONSHIP OF PANCREAS TO THE
TRANSVERSE MESOCOLON & SMALL BOWEL
MESENTERY

55. PERITONEAL RECESSES
• The largest recess is the lesser sac but there are other
recesses in the peritoneum.
• Superior Duodenal Recess
• Inferior Duodenal Recess
• Paraduodenal Recess
• Retroduodenal Recess
• Duodenjejunal Recess
• Mesenteroparietal Recess

56. • Superior Ileocaecal Recess
• Inferior Ileocaecal Recess
• Retrocaecal Recess
• Sometimes a recess may be present deep to the
apex of the sigmoid mesocolon and its related to the
left ureter and left common iliac artery

57. SUPERIOR DUODENAL RECESS
• Behind the D-J fold, left
of 4th part of duodenum.
• Directed downwards.
• Depth-1-3.5cm
• Width-0.5-2.0cm.

58. INFERIOR DUODENAL RECESS
• Fossa duodeno-jejunalis
of Treitz.
• Situated on the left of
the ascending(4th) part of
the duodenum.
• Directed upwards.
• Max depth-5.0cm.
• Max width-2.9cm

59. • Common opening for
both Superior and
inferior duodenal
recess.
• Due to vertical growth
of the two folds, and
these folds grow
extensively towards
each other and fused
laterally.

60. PARADUODENAL RECESS
• Recess venosus, fossa of
Landzert.
• Originates as congenital
peritoneal anomaly owing to
failure of mesentric fusion
with the parietal peritoneum.
• Situated on the left side of
the 4th part of the duodenum.
• Directed downwards and to
the right.
• Normally related to the IMV.
• Anomalous, related to
ascending branch of left colic
artery.

61. DUODENOJEJUNAL RECESS
• On the left side of
abdominal aorta
between D-J fold & root
of transverse mesocolon.
• Directed downwards.
• Related to pancreas
above, on left by left
kidney and left renal vein
inferiorly.

62. • Another abnormal one was
seen which is directed
upwards.
• Probably because of
malrotation of the gut.
• DJ recess are seen by
pulling the jejunum
downwards and to the right,
after the transverse colon
pulled upwards.

63. SURGICAL IMPORTANCE
• May become the site of
internal hernia.
• Segment of intestine
may enter a recess and
may be constricted and
get strangulated by the
fold guarding the
entrance to the recess.
Para duodenal hernia showing loop
of jejunum herniating.

64. OVERVIEW OF DISEASE SPREAD
• Potential routes are along the mesenteries and ligaments, via
visceral lymphatics to nodes. And by periarterial, perineural or
transvenous routes and as well as along ducts.
• For organs which are covered by peritoneum, there is an
additional pathway for spread:
I. Transperitoneal
II. Subperitoneal

65. APPLIED ANATOMY
 Intraperitoneal spread of infection & malignancy
• Spread is bi-directional, allowing disease spread via
ligaments & mesenteries to the extraperitoneal region &
vice versa.
• Lesser sac is not a common site for intraperitoneal
spread of infection as the epiploic foramen is easily
closed off by adhesions.
• It also provides a route for the spread of disease to the
anterior pararenal space, mesenteric root & transverse
colon.
• For example, gastric neoplasms can spread to involve
the superior border of the transverse colon & vice-versa.

66. • Rectro-uterine pouch(female)/rectovesical pouch (male)
is the most dependent region of the pelvis in both erect
and supine patient and hence the site of maximum fluid
stasis.
• Therefore,is a common site for abcesses, fluid,
haemorrhage & mestastasis.
 Perforation
• Most caused by a perforated duodenal ulcer or gastric
ulcer or perforated diverticulitis.
• With a perforated duodenal ulcer , free gas will pass
along the hepatoduodenal ligament to collect in the
fissure for ligamentum venosum.

67. • Colonic perforation is usually secondary to diverticulitis
and initally results in free gas passing along the sigmoid
mesentery. It then extends into the peritoneal spaces.
•

68.  Trauma
• Following a small bowel injury, fluid/blood collects
between the leaves of the small bowel mesentery
(extraperitoneal).
• It initially extends between these mesenteric folds
forming triangular pockets of fluid.
• Fluid is not seen in the paracolic gutters or pelvis.
• Following a solid organ injury, fluid/blood will initially be
seen around the injured organ.
• This extends down the paracolic gutters & into the pelvis.
• Once these are filled up there will be extension between
the leaves of the mesentery.

70. RETROPERITONEUM

71. RETROPERITONEAL SPACES
 Anterior pararenal space:
• Extends from the posterior parietal peritoneum to the
anterior renal fascia.
• Includes the ascending and descending colon, the
duodenal loop, and the pancreas.
• Continuous across the midline.
 Posterior pararenal space
• Extends from the posterior renal fascia to the
transversalis fascia.
• It’s a thin layer of fat, also known as the preperitoneal fat.

72.  Perirenal space:
• Within this space, the kidney and the perirenal fat reside
within the confines of Gerotas fascia.

73. CLINICAL IMPORTANCE
 Extravasation of Pancreatic
Fluid
• Track of pathological
peripancreatic fluid collections
depends on the involved part of
the organ, however the chest &
peritoneal cavity are not
immune.
• Primarily, the spaces around
the kidneys are the first to be
occupied by the pancreatic
fluid.

74. • In patients with acute pancreatitis,the Grey Turners sign
is caused by spread of disease from the anterior pararenal
space to the area between the leaves of the posterior renal
fascia and subsequently the lateral edge of quadratus
lamborum muscle.
• The superior and inferior lumbar triangles, sites of anatomic
weakness in the flank wall, structurally predisposes this area
to development of lumbar hernias.

75. SURGICAL APPROACH
• Can be approached and explored by several routes
including the transperitoneal route and the extraperitoneal
route.
• RETROPERITONEAL HEMATOMA- Produced by blunt
or penetrating injuries
• For practical purposes, retroperitoneum is an areolar
space without any geographic limitation.
• Hematoma may be localised or spread rapidly.

76.  OPERATIVE MANAGEMENT OF RETROPERITONEAL
HEMATOMA :
MECHANISM
OF INJURY
BLUNT PENETRATING
Zone I(centromedial) Explore Explore
Zone II(lateral) Observe Explore
Zone III(pelvic) Observe Explore

77.  2 accepted procedures used for diagnosis of
retroperitoneal injuries and for exploration of
clinicopathological entities:
• Cattell maneuver for right sided structures
• Mattox maneuver for left sided structures

78. • Cattell maneuver:
• Step 1:Incise the lateral
peritoneum along the caecum,
ascending colon and hepatic
flexure.
• Step 2: Divide the white line of
Toldt
• Step 3: Perform duodenal
mobilization(Kocherization)
• Step 4: Mobilize all right sided
anatomic structures
anteromedially.

79. • Mattox maneuver:
• Step 1:Incise the lateral peritoneum
along the splenic flexure, descending
colon and upper sigmoid.
• Step 2: Divide the white line of Toldt
• Step 3: Carefully mobilise the spleen,
including the pancreatic tail, stomach
and left colon.
• Step 4: Gently push all left sided
anatomic structures anteromedially.

80. REFERENCES
• Langmans Medical Embryology.
• Sabiston Textbook of Surgery.
• Skandalaki's Book of Surgical Anatomy.
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• The peritoneum, mesenteries and omenta: normal anatomy
and pathological processes. Eur Radiol. 1998 Jul
• Surgical anatomy of the omental bursa and the stomach based
on a minimally invasive approach: different approaches and
technical steps to resection and lymphadenectomy. J Thorac
Dis. 2017.
• Anatomy & Physiology of the peritoneum. Seminars in
Pediatric Surgery, Southhampton, 2014.

81. • Clinical importance of duodenal recesses with special
reference to internal hernias. Arch Med Sci AMS. 2017 Feb
1;13(1):148–56.
• Pancreas:Peritoneal reflections,Ligamentous connections, and
pathways of disease spread. RSNA, 2009 March.
• The subperitoneal space and peritoneal cavity: basic
concepts.
• Department of Radiology, Sloan Cancer center,New York, May
2015.

82. THANK YOU