SMALL INTESTINE

Question 1

differentiate between the small and large intestine in terms of mobility

Answer 1

the duodenum is not mobile as the proximal first part is intraperitoneal and the rest is secondarily retroperitoneal.
Jejunum and Ileum are mobile
The ascening and descending colon are secondarily retroperitoneal so aren’t mobile
the cecum has no mesentary but is commonly held in place by a peritoneal fold
the transverse colon mesentary (transverse mesocolon) adheres the transverse colon to the posterior wall of the omental bursa

Question 2

differentiate the small and large intestine in terms of lumen diameter

Answer 2

small- smaller

Question 3

differentiate the two in terms of longitudinal muscle

Answer 3

the small intestine has a continuous layer whereas the large intstine it is reduced to three bands called teniaie coli

Question 4

differentiate the two in terms of fatty tags

Answer 4

the large has fatty tags called epiploic appendages

Question 5

differentiate the two in terms of the structure of their walls

Answer 5

the large has sacculated walls and forms haustra due to tonic contraction of the longitudinal muscle

Question 6

differentiate the two in terms of their mucus membrane

Answer 6

small has permanent folds called plicae circulares and the large has incomplete folds

Question 7

differentiate the two in terms of lymphoid tissue

Answer 7

the ileum has peyers patches and the large intestine has none

Question 8

small intestine extends between?

Answer 8

pylorus and iliocoecal junction

Question 9

where is the duodenum located?

Answer 9

forms a c shaped curve around the head of the pancreas

Question 10

how long is the duodenum

Answer 10

25 cm (12 fingers)

Question 11

what are the four parts of the duodenum

Answer 11

superior, descending, horizontal, ascending

Question 12

where is the duodenal cap?

Answer 12

the first 5cm of the superior part - mobile and has mesentary. most common site of ulceration

Question 13

what is the superior part of the duodenum overlapped by

Answer 13

the liver (hepatoduodenal ligament - attaches to the greater omentum)
the gallbladder
peritoneum covers its anterior but not its posterior

Question 14

Where is the descending part located?
does it have peritonuem?
what enters posteromedial wall?

Answer 14

forms c shaped curve around head of the pancreas where the pancreatic duct and the bile duct enter it’s posteromedial wall
anterior surface of proximal and distal 1/3’s covered by peritoneum but the middle 1/3, peritoneum refelcts to form the transverse mesocolon

Question 15

where is the inferior part ?
what is it crossed by?
how is it separated from the vertebral column?

Answer 15

goes from righ to tleft and passes over the IVC and Aorta.
crossed by the SMA, SMV, root of mesentary - where these structures cross is the only part not covered anteriorly by peritoneum
seperated fro vert column by the right psoas major, IVC, Aorta, Right testicular and ovarian arteries

Question 16

Ascending part?

What is the ligament of trietz?

Answer 16

runs along left side of the Aorta and joins the jejunum at the duodenojejunal flexure.
it is suspended by the attachment of suspensory muscle of the duodenum forming the ligament of Treitz - contraction of which widens the lumen of the flexure to aid in movement of luminal contents

Question 17

how long are the duodenum and jejunum collectively?

Answer 17

6-7 m

Question 18

distinguish between them based on colour, wall, vascularity, arcades, fat in mesentary, diameter, plicae circulares and peyers patches

Answer 18

jej - deeper red (compared to paler pink), thick and heavy wall, greater vascularity as it has longer vasa recta, few large arcade loops, less fat, larger diameter, large tall closely packed plicae circulares (absent in distal part of ileum) and few peyers patches
everything opposite for ileum

Question 19

jejunum is mostly found in which region?

Answer 19

left upper quadrant

Question 20

ileum is found mainly in which segment?

Answer 20

right lower quadrant

Question 21

what is the mesentary?

Answer 21

fan shaped fold of peritoneum that attaches jejunum and ileum to the posterior abdominal wall

Question 22

what is found between the two layers of mesentary?

Answer 22

fat, autonomic nerves, superior mesentaric vessels, lymph nodes

Question 23

what are the adult derivatives of the foregut?

Answer 23

proximal duodenum - proximal to entry of bile duct, oesophagus, spleen and pancreas

Question 24

what are the adult derivatives of the midgut?

Answer 24

proximal 2/3 transverse colon, ascending colon, coecum, ileum, distal duodenum - distal to entry of bile duct

Question 25

what are the adult derivatives of the hindgut?

Answer 25

descending colon, rectum, upper anal canal, internal lining of bladder and urethra, distal 1/3 transverse colon, sigmoid colon

Question 26

what is the blood supply to the duodenum?

Answer 26

superior pancreaticoduodenal from the gastroduodenal from the common hepatic from the coeliac trunk supplies the proximal part and the distal part is supplied by the inferior pancreaticoduodenal from the SMA.

Question 27

venous drainage of the duodenum

Answer 27

follow arteries and drain into the hepatic portal vein either directly or though the splenic

Question 28

blood suppply to the jejunum and ileum

Answer 28

ileal and jejunal arteries from the SMA - when it branches it forms looped arcades with vasa recta