HLTH1008 Chap.14 Digestive Organs, Abdominal Wall and Vessels
Digestive Organs, Abdominal Wall and Vessels
The abdomen is taught as organs, a wall and a set of vessels. This chapter covers the liver, its double blood supply, lobes and porta hepatis, the gall bladder and biliary tree, the parts of the stomach and intestines, and the pancreas and spleen.
It sets out the four abdominal wall muscles and the rectus sheath, the inguinal canal and direct and indirect hernias, the branches of the abdominal aorta by direction and gut territory, the portal vein and portocaval anastomoses, and the abdominal dermatomes. Two maps, the biliary tree and the aortic branches, organise most of the facts the final exam item list asks for.
The abdominal dermatomes close the chapter and link back to the nerve chapters.
What this chapter covers
- 01
Liver blood supply, lobes and porta hepatis
- 02
Gall bladder and biliary tree
- 03
Stomach, small and large intestine
- 04
Pancreas and spleen
- 05
Abdominal wall muscles and rectus sheath
- 06
Inguinal canal and hernias
- 07
Abdominal aorta and gut territories
- 08
Portal vein and portal hypertension
Worked example · free
Tracing bile from the liver to the gut
- +1The right and left hepatic ducts unite to form the common hepatic duct.
- +1The cystic duct from the gall bladder joins it to form the common bile duct.
- +1The common bile duct meets the pancreatic duct at the hepatopancreatic ampulla.
- +1The ampulla opens into the second part of the duodenum.
Key terms
- Porta hepatis
- The opening on the liver's visceral surface for the portal vein, hepatic artery and bile duct.
- Common bile duct
- The duct formed by the common hepatic and cystic ducts.
- Coeliac trunk
- The first anterior branch of the abdominal aorta, supplying the foregut.
- Rectus sheath
- The aponeurotic sheath around rectus abdominis.
- Indirect inguinal hernia
- A hernia that enters the inguinal canal through the deep ring.
- Caput medusae
- Dilated veins around the umbilicus in portal hypertension.
- Hepatic portal vein
- The vein formed by the superior mesenteric and splenic veins that carries gut blood to the liver.
- Inguinal canal
- The 4 cm passage through the lower abdominal wall for the spermatic cord or round ligament.
- Rectus abdominis
- The vertical trunk flexor running from the pubis to the lower costal cartilages and xiphoid.
Digestive Organs, Abdominal Wall and Vessels FAQ
How much of the liver's blood comes from the portal vein?
About 70 to 80%, with the remaining 20 to 30% from the hepatic artery, according to the Week 11 lecture. Three hepatic veins then drain the liver into the inferior vena cava, and the portal vein itself is formed by the superior mesenteric and splenic veins.
What is the difference between a direct and an indirect inguinal hernia?
An indirect hernia enters the inguinal canal through the deep ring, a little above the middle of the inguinal ligament, while a direct hernia pushes through the posterior wall of the canal. The lecture notes that either can present as a lump in the scrotum or labium.
What are the signs of portal hypertension?
Where portal and systemic veins meet, raised portal pressure produces oesophageal varices in the lower oesophagus, haemorrhoids at the rectum and caput medusae around the umbilicus. The lecture lists right heart failure, hepatic vein obstruction and liver disease as causes.
Which structures pass through the inguinal canal?
In the male the spermatic cord and in the female the round ligament, with the ilioinguinal nerve and the genital branch of the genitofemoral nerve in both. The canal is about 4 cm long and runs downward and medially between the deep and superficial rings.
Which arteries supply the foregut, midgut and hindgut?
The coeliac trunk supplies the foregut through its left gastric, splenic and common hepatic branches, the superior mesenteric artery supplies the midgut and the inferior mesenteric artery supplies the hindgut. All three leave the front of the abdominal aorta between T12 and L4.
Exam move
Draw the biliary tree and say each junction aloud. Make a table of the stomach, intestine, pancreas and spleen with their parts and one fact each. Then learn the four abdominal wall muscles with their attachments and the rotation rule for the obliques, and draw the inguinal canal with both rings. Finish by drawing the abdominal aorta with its branches grouped by direction and the portal vein with its anastomoses.
Add the abdominal dermatomes, T4 at the nipple, T6 at the xiphoid and T10 at the umbilicus, and the course of lymph from the cisterna chyli through the thoracic duct.
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