General arrangement of the Abdomen

Question 1

Where is the transpyloric plane found?

Answer 1

• 9th costal cartilage
• 1/2 way from supra-sternal notch to symphysis pubis
• 1/2 way from xiphoid to umbilicus
• Linea semilunaris (lat border of rectus) cuts costal margin

Question 2

What are the contents go the epigastric region (L1)?

Answer 2

• The fundus of the gallbladder
• The end of the spinal cord
• The pancreatic body
• Origin of superior mesenteric artery
• Left and right colic flexure
• Hila of the kidneys
• The spleen

Question 3

What is the peritoneal cavity?

Answer 3

• Serous membrane which lines the inner walls of the abdominal cavity and is reflected on to viscera (organs) to a varying degree.

Question 4

What is the function of the peritoneal cavity?

Answer 4

• Permit movement of intestines during digestion independent of movement of the body wall.

Question 5

What are the features of the peritoneal cavity?

Answer 5

• Contains thin layer of peritoneal fluid.
• 2 layers:
  1. Parietal: Serous membrane layer that lines the body wall
  2. Visceral: Serous membrane layer that covers the surface of the internal organs (viscera)
• Organs are either intra-peritoneal or retroperitoneal

Question 6

What are the folds of the peritoneum?

Answer 6

1. Omentum
2. Mesentery
3. Ligaments

Question 7

What are the GI tract regions?

Answer 7

Question 8

What is the arterial supply of the abdomen and peritoneal cavity?

Answer 8

1. Foregut
   - Blood Supply: Coeliac trunk (T12)
2. Midgut
   - From 2nd part of duodenum to 2/3rd across transverse colon
   - Blood Supply: Superior Mesenteric Artery (L1)
3. Hindgut
   - From 2/3rd across transverse colon to anus
   - Blood Supply: Inferior Mesenteric Artery (L3).

Question 9

What is the venous drainage of the abdomen and peritoneal cavity?

Answer 9

• Inferior Mesenteric Vein to Splenic Vein + Superior Mesenteric Vein = Portal Vein
• Portal vein to liver (then to inferior vena cava)

Question 10

What is the lymphatic drainage of the abdomen and peritoneal cavity?

Answer 10

• Run with arteries to pre-aortic lymph nodes:
  1. Coeliac
  2. Superior Mesenteric
  3. Inferior Mesenteric

Question 11

What is the innervation of the peritoneal cavity?

Answer 11

1. Parietal layer on body wall:
   - Somatic nerves
   - Sensitive to well-localised pain the same as skin - pain, temp, touch & pressure
2. Visceral layer on organs:
   - Autonomic nerves (sympathetic
   & parasympathetic)
   - Stretch & tearing sensitive
   - Referred pain & poorly localised sensations of discomfort.

Question 12

What are the visceral afferents and their relation to pain in the abdominal region?

Answer 12

• Visceral afferents:
  1. Foregut: T5-T10
  2. Midgut: T9- T11
  3. Hindgut: L1-L2
• Poorly localised therefore can lead to referred pain from regions that share visceral afferents.

Question 13

What is the greater omentum?

Answer 13

• One of the folds of the peritoneum.
• It descends from the greater curvature of the stomach and proximal part of the duodenum, then folds back up and attaches to the anterior surface of the transverse colon.
• Lower, right & left margins free
• E.g. in inflamed appendix, omentum adheres to appendix thus localising infection to a small area of the peritoneal cavity preventing a serious diffuse peritonitis.

Question 14

What is the blood supply of the greater omentum?

Answer 14

The right and left gastro-epiploic arteries.

Question 15

What is the Peritoneal Cavity?

Answer 15

• A potential space between the parietal and visceral peritoneum.
• Contains a thin film of peritoneal fluid, which consists of water, electrolytes, leukocytes and antibodies.
• It is referred to as a potential space because excess fluid can accumulate in it, resulting in the clinical condition of ascites.
• 2 subdivisions: greater sac and lesser sac.

Question 15

What is the greater sac?

Answer 15

• Begins superiorly at diaphragm and continues inferiorly into the pelvic cavity.
• Divided into two compartments by the mesentery of the transverse colon:
  1. Supra-colic compartment – lies above the transverse mesocolon and contains the stomach, liver and spleen.
  2. Infra-colic compartment – lies below the transverse mesocolon and contains the small intestine, ascending and descending colon. This is further divided into left and right infra-colic spaces by the mesentery of the small intestine.
  *These 2 compartments are connected by the para-colic gutters. These are lateral to ascending and descending colons.

Question 16

What is a Subphrenic Abscesses?

Answer 16

• Subphrenic space = potential space in supra- colic sac.
• Subphrenic abscesses refer to an accumulation of pus in the left or right subphrenic space.
• More common on the right side due to ^ frequency of appendicitis and ruptured duodenal ulcers (pus from the appendix can track up to the subphrenic space via the right para-colic gutter).

Question 17

What is the lesser sac (Omental Bursa)?

Answer 17

• Lies posterior to the stomach and lesser omentum.
• Allows the stomach to move freely against the structures posterior and inferior to it.
• Connected with the greater sac through an opening in the omental bursa – the Epiploic foramen (of Winslow).

Question 18

Where is the epiploic foramen located?

Answer 18

• The epiploic foramen is situated posterior to the free edge of the lesser omentum (the hepatoduodenal ligament).

Question 19

What is the lesser omentum?

Answer 19

A peritoneal fold that extends from the lesser curvature of the stomach and the first part of the duodenum to the inferior surface of the liver.

Question 20

What are the divisions of the lesser omentum?

Answer 20

• Medially between stomach & liver
• Laterally between duodenum & liver

Question 21

Is there a free edge in the lesser omentum?

Answer 21

• Yes.
• Between the porta hepatis and the duodenum which contains the hepatic artery, the portal vein, the common bile duct, lymph glands, lymph vessels, and nerves, forming the hepatic hilum.
• Behind this free edge is the opening into the lesser sac or foramen of Winslow.

Question 22

What are the attachments of the lesser omentum?

Answer 22

• Upper attachment:
  1. Diaphragm
  2. Fissure for ligamentum venosum
  3. Margins of porta hepatis.
• Lower attachment:
  1. Lesser curvature of stomach
  2. First inch of duodenum.

Question 23

What are mesenteries?

Answer 23

• Peritoneal folds that attach viscera to posterior abdominal wall.
• Provides conduit for vessels, nerves & lymphatics to reach viscera.

Question 24

What are the derivatives of the dorsal mesentery?

Answer 24

1. The mesentery (small intestine)
2. Transverse mesocolon (transverse colon)
3. Sigmoid mesocolon (sigmoid colon)

Question 25

What are peritoneal ligaments?

Answer 25

• 2 layers of peritoneum that connect 2 organs to each other / an organ to the body wall & may form part of an omentum.

Question 26

List the peritoneal ligaments.

Answer 26

• Ileorenal ligament: connects left kidney to spleen
• Gastrophrenic ligament: connects stomach to diaphragm
• Gastrosplenic ligament: connects stomach to spleen
• Gastrocolic
• Gastrohepatic
  Hepatoduodenal
• Falciform ligament: liver’s reflection of peritoneum with anterior wall and was the primitive ventral mesentery.
• Round ligament (Ligamentum Teres Hepatis): hangs down from the falciform ligament, on the anterior side.

Question 27

What is Murphy’s sign?

Answer 27

• Increased discomfort or inspiratory arrest (a catching of the breath) during deep inspiration when the examiner palpates the gallbladder fossa just beneath the liver edge.

Question 28

What is Mc Burney’s point?

Answer 28

• The point on the lower right quadrant of the abdomen at which tenderness is maximal in cases of acute appendicitis.

Question 29

What are the impressions on spleen?

Answer 29

GRIP