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HAE - Quiz 5 > Lower GI Tract > Flashcards

Flashcards in Lower GI Tract Deck (43):
1

Segments of Small Intestine

Duodenum, Jejunum, Ilieum

2

Segments of Large Intestine

Colon, Rectum, Anus

3

Barriers of the Dueodenum

Begins - Distal to the pylorus of the stomach

Ends - at the Dueodenojejunal Junction

4

Duodenum

(shape and divisions)

- C-shape around the head of the pancreas

- divided into four parts

- sections 2-4 are secondarily retroperitoneal

5

1st Part of the Duodenum

- only part that has a mesentary (peritoneal) - all other sections are secondarily retroperitoneal

- part of the foregut

6

2nd/Descending Part of Duodenum

- where the common bile ducts and pancreatic duct dram into the duodenum

- drain through the major dueodenal papilla (of Vater)

7

3rd Part of Duodenum

- travels horizontally POSTERIOR to the SMVs 

8

4th Part of Duodenum

- ascends until junction with the jejunum

9

Ligament of Treitz

- suspensory muscle/ligament of the duodenum at the duodenojejunal junction

10

Duodenal Blood Supply

1st Portion - Celiac Axis (Foregut): Gastroduodenal and Superior Pancreaticoduodenal Arteries

Distal to Hepatoduodenal Ligament (Midgut) - Superior Mesenteric Artery and Inferior Pancreaticoduodenal Arteries

11

Jejunum and Ilium

- remainder of the small intestine

- gradual transition, no clear demarcation

Ilium = proximal

Jejunum = distal

12

Jejunal and Ilium Mesentary

- contains blood supply, nerves, and lympatics between two layers of visceral peritoneum

~15cm long and runs obliquely from the duodenojejunal junction to the ileocecal valve

- attached to the posterior abdominal wall

13

Jejunum vs. Ileum Mesentary Blood Supply

Jejunum: 

- longer vasa recta

- fewer vascular arcades

- more capillaries (bc more absorption)

Ilium:

- shorter vasa

- more vascular arcades

14

Efferent (motor) Nerve Supply to Small Intestines

Autonomic:

Sympathetics - 

- Pre-ganglionic Thoracic Splanchnic Nerves

- Synapse in the Preatortic Ganglia around Celiac Axis and SMA

Parasymathetics - 

- Pre-ganglionic travel in Vagus Nerve (CN X)

 

15

Peritoneal Gutters

- created by the attachments of the mesenteries

- one on either side of ascending and descending colon

**medial ascending colon gutter WILL NOT drain directly into the pelvic cavity because blocked by small bowel mesentery

16

Plicae Circulares

- mucosal folds of the small bowel

- most prominent in jejunum and gradually decrease as go towards ilium

17

Plicae Semilunares

- more widely spaced plicae/folds in the colon that do not completely incircle the lumen

18

Vasa Recta and Arcades

- vessels in the small intestine

Vasa Recta - longer in the jejunum

Arcades - more in the ilium

-- arcades allow for collateral circulation

19

Large Intestine Divisions

Cecum (appendix)

Ascending Colon

Transverse Colon

Descending Colon

Sigmoid Colon

Rectum

Anus

20

Characteristics of Large Intestine

- taeniae coli (three muscle bands) 

- haustra (outpouchings bw taeniae coli)

- appendices epiplocae (fatty collections)

21

Taeniae Coli

- muscular bands along lg intestine

22

Haustra

- outpouching of the lg intestine due to muscular bands

23

Appendices Epiploicae

- small collections of fatty tissue on the surface of the lg intestine

24

Transverse and Sigmoid Colon

- have mesenteries

25

Ascending and Descending Colon

- secondarily retroperitoneal

26

Cecum

- does not have a mesentary and is not retroperitoneal

- blind pouch of the right colon inferior to the junction of the ileum and colon

27

Rectum

- inferior to the pertoneal cavity

"Subperitoneal"

- has a complete circumferential layer of longitudinal smooth muscle

- becomes the anus at the pelvic floor

28

Transition from Midgut to Hindgut

- distal transverse colon proximal to the splenic flexure

- vascular supply switches from SMA to IMA

- parasympathetics not from pelvic splanchnics (S2-S4)

29

Hindgut Vasculature and Innervation

- IMA

Sympathetics

Post-ganglionic cell bodies in the Inferior Mesenteric Ganglia

Parasympathetic

- Pelvic Splanchnics (S2-S4)

30

Appendix

- extends from the inferior portion of the cecum where the three taeniae coli converge

- has its own mesentary and is mobile (can be located in different places)

31

Large Intestine Arterial Blood Supply - Midgut

Midgut: Cecum, Appendix, Ascending Colon, and most of Transverse Colon = SMA:

1. Middle Colic Artery

2. Right Colic Artery

3. Iliocolic Artery

(MRI)

32

Large Intestine Arterial Blood Supply - Hindgut

Hindgut: Descending Colon and Sigmoid Colon = IMA

1. Sigmoid Artery

2. Left Colic

(SoL)

 

33

Hepatic Flexure

- Right Colic Flexure between the ascending and transverse colon

34

Splenic Flexure

- flexure between the transverse and descending colon

- where the midgut switches to hindgut

35

Blood Supply to the Gut

- three branches of the abdominal aorta

1. Celiac Trunk (Foregut)

2. Superior Mesenteric Artery (Midgut)

3. Inferior Mesenteric Artery (Hindgut)

36

SMA Syndrome

- when the space between the aorta and SMA becomes so narrow that the transverse duodenum becomes obstructed

(Above the duodenum between the aorta and SMA lies the Left Renal Vein)

37

Marginal Artery

- allows collateral flow between the SMA and IMA (runs along the colon in the mesentary)

38

Venous Drainage

- into portal venous system

Midgut - Superior Mesenteric Vein - joins the splenic vein to form the portal vein posterior to the neck of the pancreas

Hindgut - Inferior Mesenteric Vein - usually drains into the splenic vein (but may enter the SMV)

 

39

Autonomic Innervation of the Intestines

Sympathetic

- Thoracic and Lumbar Splanchnic Nerves

- carry preganglionic sympathetic axons that synapse in perveterbral ganglia

Parasympathetic

Foregut and Midgut - Vagus Nerve

Hindgut - Pelvic Splanchnic Nerves (S2-S4)

- synapse with postganglionic neurons in the walls of individual organs

40

Lymphatic Drainage of the Intestines

- drain centrally to the superior and inferior mesenteric lymph nodes near the aorta → cisterna chyli → thoracic duct

41

Intraperitoneal

Liver and gallbladder

Distal esophagus

Stomach

1st portion of the duodenum

Small Intestine

Cecum

Transverse Colon

Sigmoid Colon

Spleen

42

Secondarily Retroperitoneal

Distal Duodenum

Pancreas

Ascending Colon

Descending Colon

 

43

Primarily Retroperitoneal

Aorta

Iliac Arteries

IVC

Adrenal Glands

Kidneys

Ureters

Rectum (Subperitoneal)