5.1 Digestive System Components

Question 1

Describe the superor/inferior boundaries of the anterolateral abdominal wall

Answer 1

Superior: xiphoid process + costal margins

Inferior: Iliac crest, down to ASIS, down to pubic symphysis

Question 2

What’s the surface anatomical landmark used to palpate the fundus of the gallbladder?

Answer 2

Tip of the 9th costal cartilage, right side.

Question 3

Describe the four lines that pass through the abdomen to form the 3x3 grid of sections

Answer 3

• Iliac crests (horiz)
• Subcostal border (horiz)
• Midclavicular lines (vert_

Question 4

Recall the 9 regions of the anterolateral abdominal wall

Answer 4

Top: R/L hypochondriac + epigastric

Middle: R/L Lumbar + Umbilical

Lower: R/L Inguinal + Hypogastric

Question 5

The transpyloric line is the midpoint between the…

Answer 5

Jugular notch and superior border of pubic symphysis

Question 6

What GI structures does the transpyloric plane transect?

Answer 6

• Pylorus of stomach
• Fundus of gallbladder
• Neck of pancreas
• Renal hila

Question 7

What characterises digestive accessory structures? Give 4 examples

Answer 7

• These are structures that aid in digestion, but are not part of the digestive tract itself.
• Examples include salivary glands, the gall bladder, the pancreas, and the liver

Question 8

Why are accessory digestive organs important?

Answer 8

• Digestive efficiency (absorbable components)
• Storage of nutrients (e.g. liver)
• Homeostasis regulation (pancreas, bile composition)

Question 9

Liver surface landmarks/quadrant

Answer 9

• Start at right costal margin, push upwards
• RUQ

Question 10

Stomach surface landmarks/quadrant

Answer 10

• Start at left costal margin, extends centrally
• LUQ

Question 11

Peritoneal position of liver

Answer 11

Intraperitoneal

Question 12

Peritoneal position of gallbladder

Answer 12

Intraperitoneal

Question 13

Peritoneal position of stomach

Answer 13

Intraperitoneal

Question 14

Peritoneal position of the parts of the duodenum

Answer 14

First part is intra. Remaining three are retro.

(Starts in, then leaves the system)

Question 15

Peritoneal position of ileum and jejunum

Answer 15

Entirely intraperitoneal

Question 16

Peritoneal position of all parts of the colon

Answer 16

• Only the transverse is intraperitoneal
• The remaining (asc, desc, sigmoid, rectum) are retroperitoneal; after all, don’t want shit in the peritoneum

Question 17

Peritoneal position of pancreas

Answer 17

• Tail is intra
• Rest is retro

(Tried to escape the system, but got it’s tail caught in the door)

Question 18

Peritoneal position of spleen

Answer 18

• Intra (w/ the tail of the pancreas; makes sense)

Question 19

Peritoneal position of kidneys/adrenals

Answer 19

Retroperitoneal

Question 20

The peritoneum is a serous cavity. The tissue that lines serous cavities is called…

Answer 20

Mesothelium

Question 21

Parietal vs visceral peritoneum

Answer 21

Parietal: adheres to abdominal wall
Visceral: adheres to organs

Question 22

What is the mesothelial structure between the parietal and visceral peritoneum? What travels in it?

Answer 22

• Mesentery
• Double membrane; vessels, arteries, nerves, and lymphatics run through the middle

Question 23

Too much peritoneal fluid is known as…

Answer 23

Ascites

Question 24

What are the two sacs of the peritoneal cavity? Where are they? What separates them?

Answer 24

• Lesser sac (area deep to stomach)
• Greater sac (everything except area deep to stomach)
• Separated by epicloic window

Question 25

What is the greater omentum comprised of? Where does it attach?

Answer 25

- Comprised of peritoneum; drapes down like apron - Attaches to transverse colon and to stomach

Question 26

What is the lesser omentum? Where does it run from? What are its two parts, and why is this important?

Answer 26

- Runs from duodenum/lesser curve of stomach to liver - Parts are hepatogastric and hepatoduodenal - Hepatoduodenal houses portal triad (hepatic portal vein, hepatic artery, bile duct)

Question 27

What are the names of the vessels that run on the lesser and greater curvature of the stomach? How to remember this?

Answer 27

- Lesser: gastric arteries and veins (lesser = shorter name) - Greater: gastro-omental arteries and veins (greater = longer name)

Question 28

Organs are retroperitoneal if...

Answer 28

They only have peritoneum on their anterior side (if within the balloon, this is intra)

Question 29

What is the level of the coeliac artery? What are the three branches?

Answer 29

- T12/L1 - Coeliacs are hippies; they hate SLS = Spleen (splenic artery), Liver (hepatic artery) and Stomach (left gastric artery)

Question 30

Where does the left gastro-omental artery arise from?

Answer 30

End of splenic artery, near the tail of the pancreas (does a U turn)

Question 31

Describe the branches of the common hepatic artery

Answer 31

- Gastroduodenal (r. gastro-omental, sup. pancreaticoduodenal) - Hepatic proper (L/R hepatic, cystic) - r. Gastric

Question 32

Level of sup. mesenteric artery? What other arteries are at this level?

Answer 32

- L1 (very close to coeliac) - Renal arteries also at this level

Question 33

Describe the branches of the superior mesenteric artery

Answer 33

- Inf. pancreaticoduodenal - Mesenteric branches to ileum and jejunum - Ileococlic to coecum - Right/middle colic to ascending and 2/3 of transverse colon

Question 34

Level/branches of inf. mesenteric artery

Answer 34

- Level: L3 - Left colic to 1/3 transverse and descending colon - Sigmoid branch to sigmoid colon - Superior rectal artery to rectum (until pectinate line)

Question 35

What are the two tributaries of the portal vein?

Answer 35

- Splenic vein - Sup. mesenteric vein

Question 36

Which veins can act as backups in the case of portal hTn? How does this explain caput medusae?

Answer 36

1. Paraumbuillical (medusae) 2. Colic 3. Oesophageal

Question 37

Describe the relationship between the three arms of the autonomic nervous system...

Answer 37

- 3 parts are para, sympa, and enteric - Enteric is modulated by para and sympa

Question 38

Describe the three groups of nerves that extrinsically innervate the gut

Answer 38

- Parasympathetic (vagus) - Sympathetic (prevertebral ganglia) - Sensory (dorsal root ganglia, sensory portion of vagus)

Question 39

Where do the post-ganglionic sympathetic fibres that innervate the GI tract arise from? Name these regions

Answer 39

- Arise from prevertebral ganglia - Sup. mesenteric, inf. mesenteric, coeliac, aorticorenal ganglia

Question 40

Which arm of the autonomic nervous system can be found in splanchnic nerves (pre or post ganglionic)? What are the names of the four splanchnic nerves?

Answer 40

(Preganglionic sympathetic nerves) - Greater splanchnic - Lesser splanchnic - Least splanchnic - Lumbar splanchnic nerves

Question 41

Ganglion vs plexus

Answer 41

Ganglion: group of neuronal cell bodies outside CNS Plexus: cell bodies + surrounding nerve fibres

Question 42

What are the two kinds of sympathetic neurons that act on the GI tract? What are their effects?

Answer 42

- Vasomotor (vasoconstriction) - Visceromotor (reduced secretion, absorption, and motility {sphincters closed}) B-SAM, like beta SAM for MI meds

Question 43

How does the sympathetic nervous system affect parasympathetic innervation of the GI tract, at a molecular level?

Answer 43

Can directly inhibit Ach release from parasympathetic neurons.

Question 44

Describe afferent innervation of the GI tract

Answer 44

- Vagal innervation carried to the NTS - Spinal afferents carry information via the DRG into the CNS (these are the only afferent supply to the lower GIT)

Question 45

What are the effects of vagal efferents on the GI tract?

Answer 45

- Relaxation in the anal direction - Contraction in the oral direction

Question 46

Effect of sympa/parasympa on hepatic glucose control

Answer 46

Sympa: inc. gluconeogenesis, dec. glycogenesis Parasympa: dec. gluconeogenesis, inc. glycogenesis