Describes detailed cross sectional anatomy of abdomen CT scan and segmental liver anatomy and peritoneum and retroperitoneum anatomy .

1. CT
DR SAKHER-ALKHADERI
CONSULTANT RADIOLOGIST AMC
CT ABDOMEN
ANATOMY

2. Cross section anatomy of abdominal ct scan

28. Anatomy of the liver segments

29. Anatomy of the liver segments

31. Right hepatic vein divides the right lobe into anterior and posterior
segments.
Middle hepatic vein divides the liver into right and left lobes (or right
and left hemiliver).This plane runs from the inferior vena cava to the
gallbladder fossa.
The Falciform ligament divides the left lobe into a medial- segment IV
and a lateral part - segment II and III.
The portal vein divides the liver into upper and lower segments.
The left and right portal veins branch superiorly and inferiorly to project
into the center of each segment.
Anatomy of liver segments

32. segment I : is the caudate lobe situated posteriorly around the IVC and different to
the other 7 segments. It may receive its supply from both the right and the left portal
vein and is drained directly into the IVC by one or more small hepatic veins
The remainder of the segments (II toVIII) are numbered in a clockwise fashion
starting superiorly in the left hemiliver :
segments II and III : are lateral to the left hepatic vein and falciform ligament with II
superior and III inferior to the portal plane
segment IV : lies medial to the falciform ligament, between the left and middle
hepatic veins. It is subdivided into IVa (superior) and IVb (inferior) subsegments. Easy
tip: IVa above and IVb below the portal plane. Segment IV includes the quadrate lobe.
SegmentV toVIII make up the right hemiliver and are easier to describe:
segmentV : is located below the portal plane between the middle and right hepatic
veins
segmentVI : is located below the portal plane lateral to the right hepatic vein
segmentVII : is located above the portal plane lateral to the right hepatic vein
segmentVIII : is located above the portal plane between the middle and right hepatic
veins

33. CT
PERITONEUM ANATOMY

34. Peritoneum

44. Mesoappendix

45. Inflammed mesosigmoid in diverticulitis

46. Mesenteries
True mesenteries all connect to the
posterior peritoneal wall.
These are:
The small bowel mesentery
The transverse mesocolon
The sigmoid mesentery (or
mesosigmoid)
Specialized mesenteries do not
connect to the posterior peritoneal
wall.
These are:
The greater omentum: connects the
stomach to the colon
The lesser omentum: connects the
stomach to the liver
The mesoappendix: connects the
appendix to the ileum

47. 1-The lesser omentum
2-Transverse
mesocolon
3-Small bowel
mesentery
4-Sigmoid mesentery
Mesenteries

49. The falciform ligament is the remnant of the most ventral part of the ventral
mesentery and contains the obliterated umbilical vein. It is a relative (incomplete)
barrier to the transfer of fluid from the right subphrenic space to the left subphrenic
space

55. The transverse mesocolon divides the peritoneum into the
supramesocolic and inframesocolic spaces;
Left Supramesocolic Spaces: Includes left subphrenic, and
perisplenic spaces
Right Supramesocolic Spaces: include the right subphrenic
(subdiaphragmatic) space, the Morison
pouch (subhepatic or hepatorenal space),
and the lesser sac (omental bursa).
-The right subhepatic space is an
important site of fluid collections
resulting from liver injuries because it
is the most gravity-dependent space at
this site
Peritoneal spaces

56. Peritoneal spaces
Morison pouch (subhepatic or
hepatorenal space),

57. Right and Left Inframesocolic Spaces
The right and left inframesocolic spaces are separated
from the supramesocolic spaces by the transverse
mesocolon and from the paracolic gutters laterally by the
ascending or descending colon.The smaller right
inframesocolic space is limited inferiorly by the
attachment of the small bowel mesentery to the cecum;
collections in this space generally do not extend into the
pelvis However, the larger left inframesocolic space
communicates freely with the pelvis.
Peritoneal spaces

58. Peritoneal spaces

60. Lesser sac

61. Lesser sac

62. Pelvic peritoneal space
The pelvic peritoneal space is the inferior reflection
of the peritoneum over the fundus of the urinary bladder and the front of
the rectum at the junction of its middle and lower thirds. In females, the
reflection is also over the anterior and posterior surface of the uterus and
the upper posterior vagina.In males there is only one potential space for fluid collection posterior to
the bladder, the rectovesical pouch.
In females there are two potential spaces posterior to the bladder,
the uterovesical pouch, and posterior to the uterus the
deeper rectouterine pouch (pouch of Douglas).
The layers of peritoneum on the anterior and posterior surfaces of the
uterus are reflected laterally to the pelvic side walls as the broad ligaments,
containing thefallopian tubes.

63. Pelvic peritoneal space

64. Retroperitoneum
The retroperitoneum is the part of the abdominal
cavity that lies between the posterior
parietal peritoneum and anterior to the transversalis
fascia.
It is divided into three spaces by the perirenal fascia and
is best visualised using CT or MRI.The three spaces are:
anterior pararenal space
perirenal space
posterior pararenal space
A fourth space, the great vessel space, is defined in the
recent literature

65. Retroperitoneal Spaces

66. Retroperitoneal Spaces

67. Retroperitoneal Spaces

68. S = Suprarenal (adrenal) Glands
A = Aorta/IVC
D =Duodenum (except the
duodenal cap- first 2cm)
P = Pancreas (except the tail)
U = Ureters
C = Colon (ascending and
descending parts)
K = Kidneys
E = (O)esophagus
R = Rectum
Retroperitoneal organs

69. THE END