Title: MD / Anatomy / GI
Tags: MD::anatomy::abdomen

Q: what does the myotome form?
[...]
A: skeletal muscles (epimere → posterior muscles; hypomere → anterior muscles)
Extra: dermatome forms dermis of integument and carries sensory nerves to each dermatome
sclerotome forms vertebrae, ribs, and skull base

Q: what is the fn of hyaline cartilage?
[...]
A: flexible support and to decrease friction

Q: what is the fn of elastic cartilage?
[...]
A: flexible support

Q: what is the fn of fibrous cartilage?
[...]
A: resists compression and absorbs shock

Q: what are the 3 types of loose connective tissue proper?
1. [...]
2. [...]
3. [...]
A: areolar; adipose; reticular
Extra: areolar connects skin to muscle, provides minimal support, and allows indep mvmt (e.g., lungs, around nerves, btw muscles)
adipose = cushion and insulation
reticular = supporting framework (e.g., liver, spleen, kidneys, bone marrow)

Q: what is the fn of simple squamous epithelium?
[...]
A: filtration and diffusion
Extra: stratified squamous epithelium has protective fns (e.g., barrier to microorganisms, protection against water loss)

Q: where is a typical place for columnar and cuboidal cells to be found?
1. columnar: [...]
2. cuboidal: [...]
A: digestive tract; kidneys
Extra: both secrete and absorb, just in diff locations

Q: what is the diff btw simple and stratified cuboidal epithelium?
[...]
A: simple is for secretion & absorption whereas cuboidal also has protection fns
Extra: simple cuboidal found in ducts, portions of kidney tubules, thyroid gland
stratified cuboidal found in lining of ducts of sweat glands, mammary glands, and salivary glands
stratified cuboidal much more rare

Q: what is the diff btw simple and stratified columnar epithelium?
[...]
A: simple is for digestion & kidney fns; stratified is only for protection

Q: where can pseudostratified ciliated columnar epithelium be found?
[...]
A: in respiratory areas and portions of male reproductive tract
Extra: fns: protection, secretion
e.g., in nasal cavity, trachea, bronchi

Q: which layer of the peritoneum wraps around the intraperitoneal organ?
[...]
A: visceral layer

Extra 1: celiac artery serves the foregut
SMA serves the midgut
IFA serves the hindgut

Q: which artery serves the foregut?
[...]
A: celiac artery
Extra: celiac artery serves the foregut
SMA serves the midgut
IFA serves the hindgut

Q: which artery serves the midgut?
[...]
A: SMA
Extra: celiac artery serves the foregut
SMA serves the midgut
IFA serves the hindgut

Q: which artery serves the hindgut?
[...]
A: IMA
Extra: celiac artery serves the foregut
SMA serves the midgut
IFA serves the hindgut

Q: which bone moves forward to close the epiglottis and open the esophageal lumen?
[...]
A: hyoid bone

Q: what are the 3 major constrictions on the esophagus?
1. [...]
2. [...]
3. [...]
A: cricoid cartilage (pharyngo-esophageal constriction); aortic arch (thoracic constriction); LES (phrenic constrction by the diaphragm)

Q: how does the anatomy of the GI tract prevent esophageal acid reflux?
[...]
A: angle of His and phrenic constriction

Q: what is the mesentery?
[...]
A: generic term for double thickness fold of peritoneum that connects visceral and parietal peritoneum
Extra: mesenteries prov route for blood vessels, lymphatics, nerves, and ducts to travel from body to GI organs

Q: what 3 things make up the hepatic triad?
1. [...]
2. [...]
3. [...]
A: portal vein; hepatic artery; common bile duct

Q: what structure is proximal to the ampulla of Vater?
[...]
A: sphincter of Oddi

Q: what are the 3 main arteries that split off the celiac trunk?
[...]
A: common hepatic, splenic, left gastric

Q: describe the arterial supply of the large bowel
[...]
A: SMA supplies up to distal portion of transverse colon whereas IMA supplies everything below
Extra: hence a watershed area at the left colic flexure

Q: what structures do the right and middle colic arteries serve?
right colic: [...]
middle colic: [...]
A: ascending colon; proximal 2/3 of transverse colon
Extra: left colic artery serves the descending colon & distal transverse colon AND anastomoses w/ the middle colic artery

Q: which 4 veinous routes bypass the liver to relieve portal htn?
[...]
A: distal esophageal veins, lumbar veins, rectal veins, umbilical veins
Extra: LURD

Q: which spinal nerve lvls serve the celiac plexus?
[...]
A: T5-T9

Q: which 2 lymph areas are considered deep drainage areas?
[...]
A: thoracic duct and cisterna chyli

Q: how is lymph drainage asymmetric?
[...]
A: right lymphatic duct drains RU body, RU extremity + head whereas left thoracic duct drains everthing else

Q: what does secondarily retroperitoneal mean?
[...]
A: organs which lost a mesentary during development (e.g., pancreas, duodenum, asc+desc colon)
Extra: retroperitoneal: SAD PUCKER
- Intraperitoneal: peritonealized organs having a mesentery, such as the stomach, small intestine (jejunum and ileum), transverse colon, liver and gallbladder.
- Retroperitoneal: organs without a mesentery and associated with posterior body wall, such as the aorta, inferior vena cava, kidneys and suprarenal glands.
- Secondarily retroperitoneal: organs which had a mesentery once and lost it during development, such as the pancreas, duodenum, ascending and descending colons.

which GI structures are intraperitoneal?
1. stomach
2. most of small bowel
3. transverse + sigmoid colon
4. liver
5. spleen

which GI structures are (primarily) retroperitoneal?
1. kidneys
2. ureters
3. suprarenal glands
4. rectum
Extra: KURS: kidneys, ureters, rectum, suprarenal glands (adrenals)
SAUKER: suprarenal glands, aorta, ureter, kidneys, esophagus, rectum

Q: which GI structures are secondarily retroperitoneal?
1. [...]
2. [...]
3. [...]
A: duodenum (except 1st part); pancreas; asc + desc colon

Q: A 40-year-old man is involved in a motor vehicle accident. Physical examination reveals numerous ecchymoses over the trunk and flanks, as well as a tender right abdomen without a palpable mass. Focused assessment with sonography for trauma (FAST) shows no intraperitoneal fluid collections. The hemoglobin concentration is 7.6 g/dL. Which of the following organs is most likely injured in this patient?
[...]
A: kidneys
Extra: The retroperitoneal structures can be remembered by the mnemonic SAD PUCKER: Suprarenal (adrenal ) glands, Aorta/IVC, Duodenum (except for the first part), Pancreas (except for the tail), Ureters, Colon (ascending and descending parts), Kidneys, Esophagus, Rectum.
The patient has a low hemoglobin level, but the FAST exam is negative for intraperitoneal fluid collections. These findings, along with right-sided flank pain, are concerning for a retroperitoneal bleed, secondary to kidney injury. Retroperitoneal structures are posterior to (and outside of) the peritoneal cavity. Injuries to retroperitoneal structures can cause blood or gas accumulation in the retroperitoneal space.

Q: which arteries does the celiac trunk branch into?
[...]
A: left gastric a, splenic a, common hepatic a

Q: which arteries does the SMA branch into?
1. main ones: [...]
2. others: [...]
A: ileocolic a, right colic a, middle colic a; inferior pancreaticoduodenal a, appendicular a, intestinal a

Q: which arteries does the IMA branch into?
[...]
A: left colic a, sigmoid a, superior rectal a

Q: which mesenteries support the liver?
[...]
A: falciform ligament and lesser omentum

Q: Which group of nutrients is not absorbed into the portal system to travel to the liver from the small intestine?
[...]
A: large chain fatty acids
Extra: Large chain fatty acids, such as cholesterol, are too large to cross the intestinal epithelium. Instead, they they are collected by the lymphatic system and transported via the cisterna chyli and thoracic duct into the systemic circulation.

Q: The left gastric artery supplies which structure?
[...]
A: superior aspect of the lesser curvature of the stomach

Q: The superior and inferior pancreaticoduodenal arteries anastomose to link which two arterial supplies?
[...]
A: celiac and SMA
Extra: The pancreaticodudodenal arteries anastomose to link the celiac and superior mesenteric circulations.

Q: describe the parasympathetic innervation of the GI system
[...]
A: nerves emerge directly from the brain, or from the sacrum; postsynaptic neurons are short and reside in the target organ

Q: which gut structures does CN X supply?
[...]
A: foregut and midgut
Extra: The vagus nerve (CN X) provides parasympathetic innervation to the strucures of the foregut and midgut, while the hindgut receives parasympathetic innervation from sacral segments that form the pelvic splanchnic nerves.

Q: what is teniae coli?
[...]
A: 3 longitudinal bands of smooth muscle on large colon

Q: where are G-cells found?
[...]
A: in the pyloric antrum
Extra: G-cells are neuroendocrine cells responsible for the synthesis and secretion of gastrin. They are primarily found in the pyloric antrum but can also be found in the duodenum and the pancreas. They secrete gastrin when stimulated directly by vagal efferent neurons as well as GRP neurons.

Q: describe how bile flows from the gallbladder to the duodenum
[...]
A: cystic duct to common bile duct to ampulla of Vater

Q: which structures originate from the embryonic ventral mesentary?
[...]
A: lesser omentum and falciform ligament

Q: which structures originate from the embryonic dorsal mesentary?
[...]
A: greater omentum, mesentary proper, mesocolon

Q: what are the 3 main branches of the common hepatic artery?
1. [...]
2. [...]
3. [...]
A: proper hepatic a.; r. gastric a.; gastroduodenal a.

Q: what are the 2 main branches of the gastroduodenal artery?
1. [...]
2. [...]
A: r. gastro-omental artery; sup. pancreaticoduodenal a.

Q: what are the 2 main branches of the splenic artery?
[...]
A: l. gastro-omental a. and short gastric a.

Q: what are the 3 main branches of the proper hepatic artery?
1. [...]
2. [...]
3. [...]
A: L hepatic a.; R. hepatic a.; cystic a.

Q: what are the 3 branches of the splenic vein?
1. [...]
2. [...]
3. [...]
A: l. gastro-omental vein; short gastric veins; inf. mesenteric vein

Q: what spinal levels correspond to the lesser splanchnic nerve?
[...]
A: T10-T11
Extra: -Visceral (autonomic) nervous systemic has a two neuron sequence (Pre- and postsynaptic)
-Symp: Post-synaptic is long; happens in ganglion
-Para: Post-synaptic is short; is in target organ
-Parasympathetic occurs from only brain or sacrum (Cranial sacral)
Foregut   Midgut  Hindgut
Para  CN X  CN X  S2-S4
Symp  T5-T9  T10-T11  L1-L2
T5-T9→ Greater Splanchnic Nerve
T10-T11 → Lesser Splanchnic Nerve
L1-L2 → Lumbar Nerve

Q: what spinal levels correspond to the lumbar splanchnic nerve?
[...]
A: L1-L2
Extra: -Visceral (autonomic) nervous systemic has a two neuron sequence (Pre- and postsynaptic)
-Symp: Post-synaptic is long; happens in ganglion
-Para: Post-synaptic is short; is in target organ
-Parasympathetic occurs from only brain or sacrum (Cranial sacral)
Foregut   Midgut  Hindgut
Para  CN X  CN X  S2-S4
Symp  T5-T9  T10-T11  L1-L2
T5-T9→ Greater splanchnic nerve
T10-T11 → Lesser splanchnic nerve
L1-L2 → Lumbar Nerve

Q: which nerve levels contribute to the phrenic nerve?
[...]
A: anterior rami of C3-C5 spinal nerves

Q: what are the main tributaries of the IVC?
[...]
A: paired lumbar + renal veins and hepatic veins

Q: which spinal lvls provide somatic innervation to the external anal sphincter?
[...]
A: S2-S4 (pudendal nerve)

Q: A teenager is brought to the emergency room following a severe automobile accident. An abdominal CT scan reveals significant bleeding from a large artery posterior to the body of his pancreas at about the L1-L2 vertebral level. Which artery is most likely bleeding?
[...]
A: superior mesenteric a.

Q: what vessel supplies the neck, body, and tail of the pancreas?
[...]
A: splenic artery

Q: what vessel supplies the head of the pancreas?
[...]
A: pancreaticoduodenal arterial branches

Q: what vessels drain the pancreas?
[...]
A: pancreatic veins to the splenic vein, which empties into the hepatic portal system

Q: where does fluid accumulate if the pancreas is injured?
[...]
A: lesser sac (b/c the pancreas is secondarily retroperitoneal)

Q: why is the spleen susceptible to traumatic rupture?
[...]
A: b/c it's made of weak reticular tissue

Q: For those organs that hang within the peritoneal cavity, known as intraperitoneal organs, the peritoneum extends [...] then back down to the parietal on the other side.
A: from the body wall parietal surface up and over the visceral surface of the organ

what are the 4 routes in which portal blood can escape back into the systemic circulation?
1. L and R gastric veins (portal) connect to esophageal veins (systemic); can cause esophageal varices
2. paraumbilical veins (portal) anastamose w/ body wall vasculature (systemic); drains sup and inf epigastric veins; can cause caput medusae
3. asc and desc colons have close association w/ lumbar veins (systemic)
4. superior rectal vein (portal) in close association w/ inferior rectal veins (systemic); can cause hemorrhoids

Q: Visceral afferent (sensory) fibers follow the sympathetic motor fibres back to the [...], and enter the spinal cord at the same level as other somatic afferent fibres from the body wall. Because the brain does not have a [...], the brain interprets the pain sensations coming from visceral structures as coming from somatic structures sharing the same innervation levels of the spinal cord.
A: spinal cord; sensory homunculus for visceral structures

Q: what is the first organ long chain fatty acids pass through?
[...]
A: heart
Extra: Long chain fatty acids, like cholesterol, are too large to move directly into the portal venous system. Instead, they are picked up by the lymph system where they drain to the cisterna chyli and the thoracic duct to enter the systemic venous return. As a result, these fatty acids pass through the heart prior to reaching the liver to be processed. Following a fatty meal, the lymph drainage of the GI tract will appear strikingly white and are often referred to as ‘lacteals’ because they appear to be carrying a milk-like substance.

Q: how are the intraperitoneal and retroperitoneal structures covered?
[...]
A: intraperitoneal are completely covered w/ visceral peritoneum whereas the retro are only partially covered (attached to body wall)

Q: which quadrant is the 1st-3rd part of the duodenum part of?
[...]
A: RUQ

Q: which quadrant is the head of the pancreas part of?
[...]
A: RUQ

Q: at what rib can you find the subcostal plane?
[...]
A: 10th ribs (end of true ribs)

Q: what are anatomical landmarks for the transtubercular plane?
[...]
A: at lvl of L5 vertebrae and iliac tubercle

Q: using the 9 quadrant abdo system, what are the middle three regions from top to bottom?
[...]
A: epigastric, umbilical, hypogastric

Q: using the 9 quadrant abdo system, what are the lateral three regions from top to bottom?
[...]
A: hypochondriac, lumbar, inguinal

Q: what are the layers of fascia from superficial to deep btw the skin and superficial investing fascia of the anterolateral abdo wall?
[...]
A: camper fascia, scarpa/Colles fascia

Q: what type of fascia covers the three muscles of the anterolateral abdo wall?
[...]
A: investing fascia (superficial, intermediate, and deep)

Q: what innervates the external oblique mm.?
[...] and [...]
A: thoracoabdominal nn. (T7-T11); subcostal n. (T12)

Q: what is the fn of the external oblique mm.?
[...]
A: flexes & rotates trunk, compresses & supports organs

Q: where is the origin and insertion of the int. oblique mm.?
origin: [...]
insertion: [...]
A: thoracolumbar fascia, iliac crest, connective tissue deep to inguinal lig.; ribs 10-12 & linea alba

Q: what innervates the rectus abdominis?
[...] and [...]
A: thoracoabdominal nn. (T7-T12); subcostal n. (T12)

Q: which ant. abdo wall muscles flex the trunk?
[...]
A: ext. & int. obliques and rectus abdominis

Q: what is the fn of the pyramidalis m.?
[...]
A: tense the linea alba (origin: ant. surface of pubis; insertion: linea alba)

Q: which lvls of the thoracoabdominal nn. is above the umbilicus?
[...]
A: T7-T9

Q: which lvls of the thoracoabdominal nn. is below the umbilicus?
[...]
A: T11

Q: which lvls of the thoracoabdominal nn. is at the umbilicus?
[...]
A: T10

Q: what gives rise to the sup. epigastric a.?
[...]
A: int. thoracic a. (which branches from the subclavian a.)

Q: which vessels drain the vessel of the anterolateral abdo wall skin?
[...]
A: superficial subQ venous plexus

Q: where do the superficial and inf. epigastric vv. drain into?
[...]
A: ext. iliac vein (which drains into femoral v.)

Q: which germ layer forms the peritoneum?
[...]
A: mesoderm

Q: where does the foregut start and end?
start: [...]
end: [...]
A: esophagus; major duodenal papilla

Q: where does the midgut start and end?
start: [...]
end: [...]
A: distal portion of duodenum; last 1/3 of transverse colon

Q: which major aa. does the splenic a. give rise to?
1. [...]
2. [...]
3. [...]
A: short gastric a.; left gastroomental (gastroepiploic) a.; pancreatic aa. (dorsal & great)
Extra: The splenic artery serves the spleen, but it also supplies the extensive neck, body, and tail of the pancreas, the more superior portions of the greater curvature of the stomach and the fundus of the stomach through the short gastric branches.

Q: which major aa. does the common hepatic a. give rise to?
1. [...]
2. [...]
3. [...]
A: gastroduodenal a.; right gastric a.; proper hepatic a.

Q: which aa. does the gastroduodenal a. give rise to?
1. [...]
2. [...]
A: sup. pancreaticoduodenal a.; right gastroomental (gastroepiploic) a.

Q: which aa. does the proper hepatic a. give rise to?
[...]
A: L & R hepatic aa. (R hepatic a. gives rise to cystic a.)