lecture 7

Question 1

Abdominal scarecrow:

Answer 1

• Abdominal aorta (starts at T12) = continuation of thoracic aorta
• Use the scarecrow – all single, unpaired structures supply the gut (2,3 and 6 not 9)
• All paired branches – supply abdominal wall and other structures

Question 2

Abdominal aorta aneurysms

Answer 2

• Localised enlargement of the abdominal aorta, where the diameter of the aorta at that particular level is more than 50% of its normal size
• Or the Diameter > 3cm
• Different types
• Back pain, pulsations in abdomen
• Associated with thoracic aorta and popliteal aneurysms
• Risk factors: Male, smoking, high blood pressure, family history

Question 3

Question 4

Celiac artery origin

Answer 4

arises from the aorta and passes below the median arcuate ligament

Question 5

Sup mesenteric artery origin

Answer 5

originates from the aorta between the celiac artery and renal arteries

Question 6

Inf mesenteric artery origin

Answer 6

comes off the anterolateral aspect of the left side of the aorta.

Question 7

Foregut contains

Answer 7

Lower part of oesophagus, stomach, 2/3rds duodenum
Liver, spleen, gallbladder, pancreas

Question 8

Foregut arteries:

Answer 8

Supplied by coeliac trunk; drained by splenic artery

Question 9

Note anastomosis around stomach:

Answer 9

Left and right gastric arteries and left and right gastroomental* arteries

Question 10

Question 11

Celiac trunk branches

Answer 11

left gastric artery
splenic artery
common hepatic artery

Question 12

1. Left gastric artery

Answer 12

-Smallest branch
Its ascends across the diaphragm, giving rise to the oesophageal branches before continuing anteriorly along the lesser curvature of the stomach
It forms an anastomosis with the R gastric artery

Question 13

2. Splenic artery

Answer 13

• Direct branch of celiac trunk
• Travels towards the spleen, behind the stomach
• On its course, it gives off →left gastroomental artery and short gastric arteries
• Supplies the larger curve of the stomach

Question 14

3. Common hepatic artery

Answer 14

• Goes to general area of liver
  → Proper hepatic artery (only supplies liver) → cystic artery (gall bladder); left and right hepatic arteries
  → Right gastric artery (origin may vary) – supplies other part of the lesser curvature of the stomach
  → Gastroduodenal artery (part of stomach and duodenum)
  → Supradudenal artery
  → Right gastroomental artery (forms anist. With L on greater curve of stomach)
  → Superior pancreaticoduodenal artery (pancreas and duodenum)

Question 15

Midgut

Answer 15

• Midgut stretches from last 1/3rd of duodenum, jejenum, ileum, cecum & appendix, ascending colon, 1st 2/3rd of tv colon

Question 16

Midgut blood supply

Answer 16

Supplied by superior mesenteric artery; drained by superior mesenteric vein

Question 17

Superior mesenteric artery
(midgut)

Answer 17

1. Jejenual and ileal branches (small intestine)
2. Ileocolic artery → appendicular br (ilium and colon)
3. Right colic artery (ascending colon)
4. Middle colic artery (transverse colon)

Question 18

Question 19

Hindgut

Answer 19

• Last 1/3rd of tv colon, descending colon, sigmoid colon, rectum

Question 20

Hindgut blood supply

Answer 20

• Supplied by inferior mesenteric artery; drained by inferior mesenteric vein

Question 21

Inferior mesenteric artery
(hindgut)

Answer 21

1. Left colic artery (descending colon and last 1/3rd of transverse colon also forms anist. With middle colic artery by means of the marginal artery )
2. Sigmoidal branches (sigmoid colon)
3. Superior rectal artery (rectum)

Question 22

Question 23

Anastomosis: Foregut - Midgut

Answer 23

• Pancreaticoduodenal artery surround and supply the head of the pancreas
  1. Sup pancreaticoduodenal artery:
  Comes from -> gastroduodenal artery -> Common hepatic artery -> Celiac trunk
  2. Inf pancreaticoduodenal artery:
  One of the first branches of the sup mesenteric artery

Question 24

Anastomosis: Midgut - Hindgut

Answer 24

• Between sup mesenteric artery and inf mesenteric artery
  1. Middle colic artery -> Sup mesenteric artery
  Supplies transverse colon
  2. Left colic artery -> 1st branch of inf mesenteric artery

1+2 = marginal artery of drumette – forms anastomosis

Question 25

Venous drainage IVC: Caval system

Answer 25

Located in posterior abdominal wall, ant to vert column and to the R of the abdominal aorta Formed by union of common iliac veins at L5 Ascends sup and pierces diaphragm at T8 (near central tendon) Drains the limbs, abdominal wall and paired structures

Question 26

IVC: caval system branches

Answer 26

* Common iliac veins – from lower limbs and gluteal region * Lumbar veins – from posterior abdominal wall * Renal veins – from kidneys, left adrenal gland and left testis/ovary. * Right testicular/ovarian vein from right testes or ovary * Right suprarenal vein – drains the right adrenal gland * Hepatic veins – drain the liver Found in liver, and when IVC passes behind the liver, the hepatic veins drain directly into IVC

Question 27

NOTE: * Left testicular/ovarian vein drains into the left renal vein * Left adrenal vein drains into left renal vein * No tributaries from spleen, pancreas, gallbladder drain into portal system

Question 28

Portal hepatic vein: Portal system

Answer 28

– Carries venous blood rich in nutrients from GIT – to liver for processing - Portal vein = most Nb vein in portal system - It is a point of conversion of other veins – Formed by union of splenic vein (drains area supplied by the celiac trunk) and superior mesenteric vein – Posterior to head of pancreas on L2 Tributaries: * Inferior mesenteric vein * Gastric veins * Cystic veins

Question 29

Question 30

Question 31

Portocaval anastomosis

Answer 31

- Connections between veins of the portal system and veins of the caval system

Question 32

Question 33

If there is a blockage of IVC below kidneys:

Answer 33

First collateral supply: - Have blood flow back through the common iliac vein, into inferior epigastric vein (connected to superior epigastric vein which is a contributing branch of the internal thoracic vein which drains into brachiocephalic vein and then into SVC) Second collateral supply: - Between superficial epigastric vein which is connected to the thoracic vein which also drains into the brachiocephalic and SVC Third route: - Via the lumbar vein, they contribute to the formation of the ascending lumbar vein which then directly drains into the azygos vein which then drains into the SVC

Question 34

Obstruction of the portal system – Portal hypertension

Answer 34

- Blood is redirected through the portocaval anastomoses (under lower pressure)

Question 35

Lymphatics of the gut tends to

Answer 35

follow arteries and not veins (like usual)

Question 36

Question 37

Innervation: Abdominal wall

Answer 37

Question 38

The abdominal and pelvic viscera receive their motor innervation from

Answer 38

from autonomics derived from both sympathetic and parasympathetic nervous systems - Sensory nerves also originating from the same visceral structures also travel along these sympathetic and parasympathetic fibres

Question 39

Why does pain from abdominal organs may be referred to as found away from the organ?

Answer 39

- The diffuse nature of the autonomic nervous system is responsible for the equally diffuse nature of the sensory innervation that travels along with them

Question 40

Parasympathetic fibers supplied by:

Answer 40

- L and R vagus nerve - Pelvic splanchnic nerve

Question 41

Sympathetic fibers supplied by:

Answer 41

- Thoracic splanchnic nerve - Lumbar splanchnic nerve These nerves travel to 3 ganglia; - Celiac ganglion – foregut - Sup mesenteric ganglion – midgut - Inf mesenteric ganglion – hindgut

Question 42

Parietal peritoneum innervation

Answer 42

- receives the same somatic nerve supply as the region of the abdominal wall that it lines - Pain from parietal peritoneum is well localized and severe - Is sensitive to pressure, pain, cuts and temperature

Question 43

visceral peritoneum innervation

Answer 43

- Supplied by the viscera that it covers - Pain is poorly localized - Only sensitive to stretch and chemical stimulation = dull cramping or aching sensation - Pain is thus referred to as dermatomes which are supplied by the same sensory ganglia and spinal chord segments as the fibers innervating the viscera

Question 44

Referred pain:

Answer 44

- Pain perceived at a location which is not the location of the painful stimulus - Most viscera only innervated by autonomic nerves, thus visceral/referred pain is conducted via different afferent

Question 45