Anatomy overview

Question 1

Describe how the abdominal wall is lined with muscle (superior, inferior, posterior and anterior)

Answer 1

• Superiorly: The diaphragm
  
  • Posteriorly: The iliacus, psoas major, psoas minor and quadratus lumborium
  • Anteriorly: Transverse abdominis, internal oblique, external oblique, rectus abdominis and the linea alba
  • Inferiorly: The pelvis floor

Question 2

What is the function of the peritoneum?

Answer 2

keep the gut tube in contact with a blood supply

Question 3

Describe the different type of peritoneum

Answer 3

• Viscera:l surround an organ
  
  • Parietal: on the body wall
  • Peritonised e.g. the small intestine
  • Retroperitoneal e.g. duodenum
  • Omenta are double folds passing from the stomach and duodenum to other organs or the body wall
  • Ligaments: double layers of peritoneum which span between organs and organs and the body wall

Question 4

Describe the features which act to increase absorptive surface area along the gastrointestinal tract

Answer 4

Small intestine
	• Plica
	- Corkscrew like folds
	• Villi
	- Absorb: fats, amino acids, monosaccharides, water, minerals, vitamins, peptides, NaCl
	- Crypt of Lieberkühn: secretes (water + NaCl) 
	- Lacteal
	- Goblet cells
	- Vessels
	• Microvilli

Question 5

How does the blood supply get to an organ within a mesentery?

Answer 5

• Atrial branched travel between double folds of peritoneum, such as mesenteries and omenta, and thereby gain access to peritonised organs
  
  • Therefore, an arterial branch supplying an organ with a mesentery, will travel between the fold of that mesentery

Question 6

What organs are supplied by each of the different blood supplies (foregut, midgut, hindgut, liver, gallbladder and spleen) ?

Answer 6

• Celiac artery supplies the foregut
  
  • Superior mesenteric artery supplies the midgut
  • Inferior mesenteric artery supplies the hindgut
  • The liver and gallbladder are supplied by the hepatic artery
  • The spleen is supplied by the splenic artery

Question 7

Describe the anatomy of the GI tract and assign general physiological functions to each of its components

Answer 7

• Mouth: Chewing and breaking up food, saliva is added as lubricant
  
  • Oesophagus: conduit between the mouth and stomach
  • Stomach: Digestion of proteins, foodstuff reduced to liquid form, storage and sterilisation
  • Pancreas: digestive enzymes for digestion of fats, carbohydrates and proteins
  • Liver: bile salts for digestion/ absorption of fats in the small intestine
  • Gallbladder: stores and concentrates bile
  • Small intestine: Final stages of chemical digestion and nutrient absorption
  • Large intestine: Water absorption, bacterial fermentation and formation of faeces

Question 8

Explain the concept of the portal venous system and its anastomosis with the sympathetic blood supply. What is it formed from?

Answer 8

• All the blood that has been round the gut tube goes to the liver before returning to the heart
  
  • The portal vein is formed by the union of the splenic vein and the superior mesenteric vein
  • The blood in the hepatic portal vein is high in nutrients but low in O2
  • The blood in the hepatic artery is low in nutrient but high in O2

Question 9

Describe the venous drainage of the GI tract

Answer 9

• Celiac vein supplies the foregut
• Superior mesenteric vein supplies the midgut
• Inferior mesenteric vein supplies the hindgut
Splenic vein supplies the spleen

Question 10

Describe the innervation of the abdominal organs

Answer 10

• Sympathetic
- Abdominopelvic splanchnic nerves (greater, lesser and least)
- Paravertebral sympathetic ganglia
- Abdominal aortic plexus
• Parasympathetic
- Anterior and posterior vagal trunks
- Pelvic splanchnic nerves (S2, 3 and 4)