Chapter 7 Retriperitoneal Structures and Development of Mesenteries

Question 1

Which side does the aorta descend along lumber bodies?

Answer 1

Left anterior surface of lumbar vertebral bodies

Question 2

Which level does the aorta bifurcate into the the two common iliac arteries?

Answer 2

Lower border of L4

Question 3

Which level does the common iliac artery bifurcate and where do its branches go?

Answer 3

Common iliac artery bifurcates at level L5. The internal iliac artery enters the pelvis. The external iliac artery passes under the mid inguinal point to enter the thigh as the femoral artery.

Question 4

How many branches does the abdominal aorta give off behind the tendinous arches of psoas muscles?

Answer 4

4 branches (paired), quickly entering the neurovascular plane and supplying skin and muscles of abdominal wall.

Question 5

What is the median sacral artery?

Answer 5

This occurs at the bifurcation of the aorta and runs down into the pelvis to supply the posterior pelvic wall.

Question 6

Besides the lumbar arteries? what are the other 4 pairs of arteries arising from the aorta?

Answer 6

Inferior phrenic arteries
Suprarenal arteries
Renal arteries
Gonadal arteries

Question 7

What does the inferior phrenic arteries supply?

Answer 7

Diaphragm

Question 8

What are the 3 unpaired branches that arise from the anterior midline of the aorta? Which level do they arise?

Answer 8

Coeliac trunk L1
Superior mesenteric artery L1
Inferior mesenteric artery L3

Question 9

What does the coeliac trunk and the superior mesenteric artery supply?

Answer 9

The gut and associated structures as far down as the last part of the transverse colon.

Question 10

What does the inferior mesenteric artery supply?

Answer 10

The distal part of the transverse colon and descending colon, and part of the rectum and anal canal.

Question 11

Where do lumbar veins drain into?

Answer 11

Abdominal parts of the azygos and hemiazygos veins (ascending lumbar veins)

Question 12

How does the IVC and its iliac vein bifurcation run along with the aorta?

Answer 12

IVC penetrates the diaphragm at T8. It immediately passes through the liver and emerges to the right of the abdominal aorta with the right crus lying between the 2. It bifurcates to the right and left common iliac veins behind the right common iliac artery. The iliac veins run on the inferiomedial surfaces of the iliac arteries.

Question 13

Where does the blood from the gut drain into?

Answer 13

Portal vein & Renal vein

Question 14

What are the tributaries of the IVC?

Answer 14

The 2/3 hepatic veins that arise and drain into the IVC from within liver substance, the right gonad vein, right suprarenal vein, right inferior phrenic vein.

Question 15

Where does the left suprarenal, gonadal vein drain into?

Answer 15

Left renal vein

Question 16

Where does the left inferior phrenic vein drain?

Answer 16

Into the left suprarenal vein.

Question 17

What are the layers encapsulating the kidneys?

Answer 17

Kidneys have a thin capsule. Perirenal fat lies between this capsule and the renal fascia. Between the renal fascia and the fascia transversalis, there is another layer of pararenal fat.

Question 18

Which kidney is higher and at what level?

Answer 18

Hilum of kidneys should be at level of transpyloric plane (L1), however, the left kidney is a bit higher and the right is a bit lower.

Question 19

What nerves run along the posterior abdominal wall between the muscles and the kidneys?

Answer 19

Subcostal, iliohypogastric and ilioinguinal nerves.

Question 20

Where do kidneys begin to develop?

Answer 20

In the pelvis

Question 21

Where do the ureters run down?

Answer 21

They run down the tips of the lumbar transverse processes and then across the bifurcation of the common iliac arteries and into the pelvis.

Question 22

What blood supplies the ureters?

Answer 22

Renal arteries, common iliac arteris and the aorta

Question 23

Where do kidney stones often lodge?

Answer 23

In the ureter when it runs over the common iliac vessels.

Question 24

Describe the structure of the kidney hilum

Answer 24

Ureters enter behind renal arteries.
Renal arteris lie posterior to renal veins.
Ureters opens out in the kidney to become renal pelvis.
The renal pelvis along with larger vessels and some fat is known as renal sinus.

Question 25

Describe the structure of the kidney

Answer 25

Renal pelvis bifurcates or trifurcates to form the major calyces. Each major calyx bifurcates or trifurcates to form minor calyces. There is an outer cortex and an inner medulla, whos apical site faces the minor calyces. The medulla consists of renal pyramids.

Question 26

Name the 3 arterial blood supplies to the suprarenal glands

Answer 26

Superior suprarenal artery is a branch of the inferior phrenic artery
Middle suprarenal artery is a branch directly from the abdominal aorta
Inferior suprarenal artery is a branch from the renal artery

Question 27

Describe venous drainage of the suprarenal glands

Answer 27

Only one vein drains into the IVC for the right side but the renal vein for the left side.

Question 28

What is the serous endothelium?

Answer 28

This lines the peritoneal cavity within the abdomen.

Question 29

How is the dorsal mesentary formed?

Answer 29

Inititally, a long thin gut tube lies in front of the aorta behind the peritoneal sac. This is in contact with the visceral peritoneum. The gut tube moves forwards into the abdominal cavity drawing a double layered fold of peritoneum that is anchored at the back in front of the aorta. This double layered stretched out portion of the peritoneum is called the dorsal mesentary.

Question 30

Where is the root of the dorsal mesentery?

Answer 30

This is when the dorsal mesentary becomes continuous with the parietal peritoneum at the posterior abdominal wall.

Question 31

Which structures begin to develop in the dorsal mesentary?

Answer 31

Dorsal part of the pancreas and the spleen

Question 32

Which structures begin to develop in the ventral mesentary?

Answer 32

Ventral part of the pancreas and the liver

Question 33

Why is there a free lower border to the ventral mesentary?

Answer 33

Ventral mesentery exists only in the upper part of the abdominal cavity so there is a free lower border.

Question 34

What does the falciform ligament connect?

Answer 34

It connects the liver to the anterior abdominal wall or the diaphragm above. It has a free lower border.

Question 35

What does the lesser omentum connect?

Answer 35

This connects the liver to the lesser curvature of the stomach.

Question 36

What does the gastrosplenic ligament connect?

Answer 36

This connects the greater curvature of the stomach to the spleen.

Question 37

Which ligament connects the spleen and the left kidney?

Answer 37

Lineorenal ligament

Question 38

Before rotation occurs, name the ligaments formed from anterior to posterior abdominal walls.

Answer 38

Falciform ligament, lesser omentum, gastrosplenic ligament, lineorenal ligament, greater omentum

Question 39

Where does the greater omentum pass?

Answer 39

This passes from the greater curvature of the stomach below the gastrosplenic ligament to the root fo the mesentery on the posterior abdominal wall

Question 40

What occurs during rotation?

Answer 40

The stomach and the attached mesenteries containing the various gut derivatives rotate to the right side of the abdominal cavity. The root now shifts to the left of the aorta along with the spleen. The pyloris of the stomach and future duodenum are carried over to the right.

Question 41

How does the duodenum become part of the posterior abdominal wall?

Answer 41

The dorsal mesentery of the future duodenum rotates rightwards and lies flat against the parietal peritoneum on the posterior wall of the abdomen. This melts away to form part of the posterior abdominal wall.

Question 42

How is the duodenum and pancreas a secondarily retroperitoneal structure?

Answer 42

As the dorsal mesentery of the duodenum and pancreas is rotated to the right, it lies flat agains tthe parietal peritoneum on the posterior wall of the abdomen and fuses. The single remaining layer of the mesentery covering the front of the duodenum behaves like the parietal peritoneum so the duodenum becomes a secondarily retroperitoneal structure.

Question 43

How is the epiploic foramen formed?

Answer 43

The free edge of the lesser omentum has turned over to the right and this is the opening to the lesser sac. This free edge is now tied to the posterior abdominal wall at the lower end. The ligaments that now attach liver to diaphragm and posterior abdominal wall limit the boundaries of lesser sac above and posteriorly.

Question 44

What does the midgut consist of?

Answer 44

Part of the duodenum, ileum, jejunum, and more than half of the colon.

Question 45

What does the hindgut consist of?

Answer 45

Distal third of the transverse colon and the sigmoid colon, rectum and upper anal canal.

Question 46

Which artery supplies the midgut?

Answer 46

Superior mesenteric artery

Question 47

Which artery supplies the hindgut?

Answer 47

Inferior mesenteric artery