Anatomy

Question 1

Average length small bowel in adult?

Answer 1

6m

Question 2

Where does the small bowel proper begin?

Answer 2

Duodeno-jejunal flexure: lies to the left of L2 in the root of the transverse mesocolon (near ligament of Treitz).

Question 3

Where does the mesenteric root of the small bowel run?

Answer 3

Runs from L2 near ligament of Treitz –> extends obliquely downwards and to the RHS for 12-15cm to overlie the sacroiliac joint.

Question 4

What are the features of the jejunum? (cf ileum)

Answer 4

• Different pattern of vascular arcades
• Wider diameter
• Wall is thicker due to valvulae conniventes (mucosal folds; important to identify on AXR)

Question 5

Where are Peyer’s patches located?

Answer 5

Submucosa of the distal ileum

Question 6

What is the vitelline duct?

Answer 6

AKA omphalomesenteric duct. a long narrow tube that joins the yolk sac to the midgut lumen of the developing fetus

Question 7

How may persistence of the vitelline duct present?

Answer 7

1) Vitello-intestinal fistula: open communication between ileum and umbilicus.
2) Meckel’s diverticulum: free diverticulum of the terminal ileum ~25-30cm from ileocaecal valve. Ectopic gastric mucosa may be present.
3) Fibrous strand: from umbilicus to either anti mesenteric border of ileum or to apex of Meckel’s diverticulum; acute intestinal obstruction and strangulation may occur.

Question 8

What is a microbiological complication of decreased bowel mucosal protection in obstruction or hypo perfusion?

Answer 8

SIRS. Breakdown of mucosal protection allows bacteria to translocate and enter the portal blood –> endotoxins in circulation –> SIRS –> multi organ failure.

Question 9

Avg length of LB in adults?

Answer 9

135cm

Question 10

How can LB be distinguished from SB?

Answer 10

Greater diameter, fatty appendages (epiploic appendices), sacculated appearance due to 3 longitudinal smooth muscle strips (taeniae coli).

Question 11

Describe the origins of blood supply of the LB.

Answer 11

Results from embryology: first part of colon (caecum > splenic flexure) from midgut; remainder from hindgut.
Midgut origin: branches of SMA (ileocolic, right and middle colic arteries).
Hindgut origin: IMA branches (left colic and sigmoid arteries).

Question 12

What is the venous drainage of the LB?

Answer 12

Blood from proximal colon enters tributaries of superior mesenteric vein. Joined by splenic vein to form the portal vein leading to liver.
Distal colon drains into inferior mesenteric vein which joins the splenic vein.

Question 13

Arterial supply to oesophagus?

Answer 13

Left gastric artery and left inferior phrenic artery

Question 14

Venous drainage of oesophagus?

Answer 14

• Left gastric vein -> portal venous system.

- Oesophageal veins -> azygous vein -> IVC (systemic).

Question 15

Innervation of oesophagus?

Answer 15

PNS: anterior and posterior gastric nerves (vagal nerves)
SNS: thoracic trunks of greater splanchnic nerves

Question 16

Structural tissue layers of oesophagus?

Answer 16

Mucosa, submucosa, muscularis propria (inner circular, outer longitudinal).

Question 17

Arterial supply to lesser curvature of stomach?

Answer 17

Right and left gastric arteries (from coeliac trunk)

Question 18

Arterial supply to greater curvature of stomach?

Answer 18

Right and left gastroepiploic arteries (from gastroduodenal and splenic a. respectively)

Question 19

Arterial supply to fundus of stomach?

Answer 19

Short and posterior gastric artery (from splenic artery)

Question 20

What are the retroperitoneal structures?

Answer 20

SAD PUCKER
Suprarenal glands
Aorta / IVC
Duodenum (2-4th segment)
Pancreas
Ureters
Colon (asc and desc ONLY)
Kidneys
oEsophagus
Rectum