Anatomy of GI

Question 1

Abdominal planes and regions

Answer 1

▪️2 mid-clavicular lines 
▪️transpyloric plane- under costal margin (L1)
▪️transtubecular plane -ischial tuberosities (L5)
-L/R hypochondriac 
-epigastric 
-L/R lumbar/flank 
-umbilical 
-L/R iliac/groin 
-hypogastric

Question 2

Palatoglossal and palatopharyngeal arches

Answer 2

▪️separates oral cavity and oropharynx
▪️inbetween arches are palatine tonsils
▪️palatoglossus muscle- elevates soft palate during swallowing to allow food to move into oropharynx

Question 3

Tongue structure

Answer 3

▪️fungiform papillae- mushroom like, large, margins of tongue
▪️filiform papillae- cone-shaped, small, mucosal projections, centrally (no taste buds)
▪️vallate papillae- cylindrical in V-shape, largest, 8-12, anterior to terminal sulcus
▪️foliate papillae- linear folds of mucosa, sides of tongue

-increase contact area with food

Question 4

Oesophagus structure

Answer 4

▪️23-37cm long
▪️3 parts
-cervical- continuous with oropharynx 
-thoracic- T1-T10
-abdominal- hiatus to cardia of stomach, short
▪️constrictions 
-cervical- C5-C6 due to cricoid cartilage 
-thoracic- aortic arch 
-abdominal- oesophageal hiatus

Question 5

Liver function

Answer 5

▪️production of bile
▪️metabolism of protein, carbohydrates and fats
▪️filters blood, removes bacteria
▪️production of heparin- anticoagulant

Question 6

Diaphragmatic surface of the liver

Answer 6

▪️smooth and domed
▪️anterior, superiorly, posterior aspects
▪️subphrenic and hepatorenal recess

Question 7

Visceral surface of the liver

Answer 7

▪️inferior aspect covered in peritoneum except fossa of gallbladder and porta hepatis
▪️oesophagus, right part of the stomach, lesser omentum, gallbladder, right colic flexure, transverse colon, right kindness, right suprarenal gland

Question 8

Liver structure

Answer 8

▪️R and L lobes divided by IVC and gallbladder
▪️caudate lobe and quadrate lobe- arises from right lobe, functionally from left lobe
▪️independent functional wedge-shaped units which each have a branch of portal vein, hectic artery and bile duct

Question 9

Peritoneum reflections of the liver

Answer 9

▪️intraperitoneal except superior surface where it is in contact with diaphragm- bare area
-liver grows v fast therefore ends up bursting from peritoneum
▪️margins of bare area
-falciform ligament- anterior, in between R and L lobes
- R and L coronary ligament- surrounds bare area
-R and L triangular ligament- corner of bare area
▪️allows movement of liver during deep inspiration, but limits movement of liver

Question 10

Micro anatomy of liver

Answer 10

▪️surrounded by fibrous capsule
▪️liver lobules with central portal vein in the middle which drains into IVC
▪️arterial and venous blood passes in between hepatocytes through sinusoids into CPV
▪️bile produced by hepatocytes passes in opposite direction

Question 11

Bile production and secretion

Answer 11

▪️digests and absorb fats in SI
▪️produced at a constant rate- 40mls per hours- even when not eating
▪️stored and concentrated (X5) in gallbladder- if have a very fatty meal
-R/L hepatic duct, common hepatic duct joins with cystic duct, bile duct joins pancreatic duct, secreted through major duodenal papilla into duodenum

Question 12

Stomach structure

Answer 12

▪️muscular bag
▪️cardia- continuous with oesophagus
▪️fundus-sits above entry level of the oesophagus, filled with air
▪️body
▪️pylorus-pyloric antrum, pyloric canal, pyloric sphincter
▪️lesser curvature- lesser omentum
▪️greater curvature-greater omentum

Question 13

Lesser omentum

Answer 13

▪️double layer of peritoneum attached to the stomach and the liver
-hepatogastric ligament- liver to lesser curvature
-heptoduodenal ligament- liver to duodenum-bile duct and portal vein run along the border of the ligament
▪️epicolic foramen- only access point to get behind the stomach

Question 14

Greater omentum

Answer 14

▪️quadruple layer of peritoneum from greater curvature of stomach covering SI and LI
▪️hangs down like an apron and can isolate an infection and surround it
▪️very thick, fat in between layers- protects organs

Question 15

Duodenum

Answer 15

▪️c-shaped, 25cm
▪️1st part (duodenal cap) is the widest part of SI
-site of duodenal ulcers, 30mins from when you eat is when pain occurs
▪️2nd part, where bile duct and pancreatic duct drain out
- anything behind this point is foregut, anything in front is midgut- different BV and nerve
▪️3rd part, SMA/SMV pass anterior- if they harden they compress tube and cause vomiting
▪️reteroperitoneal except first part-attached to hepatoduodenal ligament

Question 16

Jejunum and Ileum

Answer 16

▪️supplied by SMA
▪️jejunum 
-2/5
-upper left quadrant 
-larger diameter lumen and thicker walls 
-prominent plicae circulares 
-less prominent arcades, longer vasa recta 
▪️ileum 
-3/5
-thinner walls 
-fewer and less plicae circulares 
-prominent arcades, shorter vasa recta 
-more mesenteric fat

Question 17

Large intestine

Answer 17

▪️taeniae coli- longitudinal strips of muscle- run anteriroly and posterior of large bowel only
▪️omental appendices- fatty deposits which hang of LI
▪️haustra-indentations of LI
▪️A and D colon are reteroperitoneal
▪️transverse and sigmoid colon are intraperitoneal

Question 18

Anal canal

Answer 18

▪️puborectalis muscle (lavator ani) forms sling around junction of rectum and anal canal-kinks GIT giving control
▪️external sphincter muscles- deep, superficial, subcutaneous
▪️anal columns extend superiorly, join inferiorly at anal valves, dips in the valves are the anal sinuses
-form a circle- pectinate line, below line is transition zone-non keratinised stratified squamous epithelium- from skin

Question 19

Peritoneum Male Vs Female

Answer 19

▪️Male
-closed off, no external connection
▪️female
-connection through valine, uterus, Fallopian tubes-gap between ovaries and fimbriae