GIT anatomy Flashcards
What are the 9 regions of the abdomen?
What are the 12 structures crossed by the Transpyloric Plane? and what level is it at?
At the L1 vertebra level:
Structures:
- Pylorus (end of stomach)
- Pancreatic neck
- Duodenojejunal flexure
- Fundus of gallbladder
- 9th costal cartilage
- Hila of kidneys
- Origin of portal vein
- Transverse mesocolon
- 2nd part of Duodenum
- Superior mesenteric artery origin
- Hilum of spleen
- Termination of spinal cord
Describe the arcuate line and what you’d see superior and inferior to it
Arcuate line -> at the end of the rectal sheath
Hernias more common below the arcuate line because don’t have rectal sheath to protect
What are the 3 umbilical folds?
Median:
- Urachus (embryological)
Medial:
- Umbilical arteries (no longer patent)
Lateral:
- Inferior epigastric vessels (still patent) - DONT break this in surgery
What are the borders of the inguinal canal?
Roof:
- Transversalis fasci
- Internal oblique
- Transversus abdominus
Anterior wall:
- Aponeurosis of external oblique
- Internal oblique
Posterior Wall:
- Transversalis fascia
Floor:
- Inguinal ligament
- Lacunar ligament
Which layer of the spermatic cord doesn’t get pulled down with the descent of the testes?
- Transversus abdominus
what are the Inguinal Canal Contents? (think of 3s)
3 Arteries:
- Artery to vas deferens
- Testicular artery
- Cremasteric artery
3 Nerves:
- Genital branch of genitofemoral nerve
- Iliolingual nerve
- Sympathetic fibres
3 Fascias:
- External spermatic fascia
- Cremasteric fascia
- Internal spermatic fascia (transversalis fascia)
3 Others:
- Pampiniform venous plexus
- Ductus deferens
- Lymphatics
what are the 2 types of inguinal hernias? describe their relation to the inferior epigastric vessel
Direct:
- medial to the inferior epigastric vessel
Indirect:
- lateral to the inferior epigastric vessel
what is the presenting symptom of inguinal hernias and what is the way to differentiate between direct and indirect?
Presenting symptoms:
- lump in groin -> minimises when lying down
How to differentiate:
- if you press down on the deep ring and the hernia still protrudes, it is direct.
How do you differentiate between the inguinal and femoral hernia?
- Inguinal is superomedial to pubic tubercle
- whereas femoral is inferolateral to pubic tubercle
What is the pathophys of Testicular torsion?
Testicle rotated around spermatic cord -> blocks blood flow to testicle // can lead to necrosis
What are the symptoms of Testicular Torsion?
- sudden sever pain in scrotum and affected side of lower abdomen
What are causes of Testicular torsion?
- testicle not strongly attached to scrotum at birth
- minor trauma around scrotum
- vigorous physical activity
What is the treatment of testicular torsion?
immediate surgical detorsion
What is Bell Clapper syndrome?
- your testicles hang in your scrotum and swing freely, like a clapper in a bell
- this happens because gubernaculum is absent
What is the greater sac? where is it? what are the compartments of it?
= largest part of the peritoneal cavity
- it is anterior and inferior in the abdomen
- it has supracolic and infracolic compartments
What are the borders of the Lesser Sac (Omental bursa)?
Anterior:
- Liver
- Gastrocolic ligament
- Lesser omentum
Left:
- Kindey + adrenal gland
Right:
- Epiploic foramen
- lesser omentum
- greater sac
Posterior:
- Pancreas
Epiploic foramen of Winslow. what is it? what are its borders?
= passage between the lesser and greater sac
Anterior border:
- Hepatoduodenal ligament (contains portal tria)
Posterior:
- IVC
Superior:
- Liver
Inferior:
- Duodenum & hepatic artery
Peritoneal cavity in the pelvis. what is its importance? for males and females?
= peritoneal space where fluid can accumulate when upright
Males:
- Rectovesical pouch (bw rectum and bladder)
Females:
- Rectouterine pouch (pouch of Douglas) (bw rectum and uterus)
- Vesicouterine pouch (bw bladder and uterus)
In men, the peritoneal cavity is completely closed but in women, the uterine tubes open up the cavity -> potential site of infection
What are omenta?
= folds of peritoneum that attach organs to each other
What is mesentery?
a fold of membrane that attaches the intestine to the wall around the stomach area and holds it in place
Describe the greater omentum. what type of mesentery? how many layers? where is it?
= dorsal mesentery
- 4 Layers
- from greater curvature of the stomach -> descends over t. colon, jejunum, ileum -> ascends back up to the t. colon
describe the lesser omentum. what type of mesentery? where is it attached? what is it formed from?
= ventral mesentery
- attached to lesser curvature of the stomach & liver
- formed from hepatogastric and hepatoduodenal ligament
What is the arterial supply of the foregut and its vertebral level?
- Celiac trunk
- T12
What supplies the midgut and its vertebral level?
- Superior mesenteric artery (SMA)
- L1
What supplies the hindgut and its vertebral level?
- Inferior mesenteric artery (IMA)
- L3
What arteries does the Celiac trunk give rise to and what organs do they supply? and what does the celiac trunk branch from?
Celiac trunk from the Abdominal Aorta
Give rise to:
- Left gastric artery -> stomach, adjacent portion of the oesophagus
- Splenic artery -> spleen, stomach, pancreas
- Common hepatic artery -> liver, stomach, gallbladder, duodenum, pancreas
What organs does the SMA supply?
- Pancreas
- small intestine
- appendix
- first 2/3rds of large intestine
What does the IMA supply?
- last third of large intestine
Describe an Abdominal Aortic Aneurysm. what is the most common type? what type is considered a medical emergency and whats not? and what are the presentations of the medical emergency one?
Aneurysm = abnormal swelling or bulge in blood vessel
Most common = Infrarenal (between the Renal artery and IMA)
- also Unruptured AAA and Ruptured AAA (med emergency)
- Ruptured AAA presents with severe pain, hypotension, pulsatile abdominal mass
What is a peptic ulcer and what can it be caused by?
= defect in muscularis mucosa layer of GIT -> extends into further layers
Cause:
- H.pylori
- NSAIDs
Where do gastric ulcers and duodenal ulcers occur? what arteries can they potentially affect?
Gastric:
- Splenic artery (posterior)
- Left and right gastric artery (lesser curvature)
- L/R gastroepiploic artery (greater curvature)
Duodenal:
- gastroduodenal artery
What are the branches of L gastric artery which arises from the celiac trunk? what does each supply?
What are the branches of the splenic artery which arises from the celiac trunk? what does each supply?
What are the branches of the Common hepatic artery which arises from the celiac trunk? what does each supply?
What are the branches that arise from the SMA and what do they supply?
What is Nutcracker Syndrome?
- SMA passes anteriorly to left renal vein, the unicate process and 3rd part of the duodenum
- because of this, an aneurysm can compress the left renal vein -> Nutcracker Syndrome
What are the jejunal and ileal arteries?
Jejunum:
- longer vasa recta with fewer gaps
Ileum:
- shorter vasa recta with more gaps
What branches arise from the IMA and what does they supply?
IMA branches diagram
What is systemic venous drainage and what does it drain?
- IVC drains all structures below diaphragm EXCEPT spleen, pancreas, gallbladder and abdominal part of GI tract. The others are drained by the Portal Venous System
- IVC is also retroperitoneal
What is the difference between Hydrocele and Varicocele and what are they?
Hydrocele:
= fluid accumulation w/in tunica vaginalis in scrotum
- Clin presentation -> TRANSILLUMINATES, painless swelling
Varicocele:
= pampiniform plexus of scrotum is engorged due to obstruction of spermatic vein (left side more affected)
- Clin presentation -> does NOT TRANSILLUMINATE, feels like a bag of worms on palpation
Describe the portal venous system. What union forms portal vein?
= carries blood from GI viscera into liver for metabolism and nutrient sequestration
- Portal vein = union of SMV and splenic vein (IMV drains into splenic)
What are the main veins of GIT and branches and what does it drain?
What is Portal Hypertension? causes?
= increased pressure within the portal venous system
Pre-hepatic:
- Portal vein thrombosis (a blood clot within blood vessels that limits the flow of blood)
Intrahepatic:
- Cirrhosis (a type of liver damage where healthy cells are replaced by scar tissue)
Post-hepatic:
- hepatic outflow obstruction
Presentation of portal hypertension?
- Dilated blood vessels in Oesophagus and rectal
- Splenomegaly (enlarged spleen)
- Ascites (fluid collection in abdomen spaces)
Veins of GIT diagram
Nerves of GIT diagram
Table summary of GIT nerves
Greater splanchnic nerves
- Type of innervation
- Origin
- Synapse
- Target
- Sympathetic
- T5 - T10
- Celaic ganglion
- Foregut derivatives
Lesser splanchnic nerves
- Type of innervation
- Origin
- Synapse
- Target
- Sympathetic
- T10 - T11
- Celiac & superior mesenteric ganglion
- Midgut derivatives
Least splanchnics
- Type of innervation
- Origin
- Synapse
- Target
- Sympathetic
- T12
- Aorticorenal ganglion
- Kidney and suprarenal gland
Sacral splanchnics
- Type of innervation
- Origin
- Synapse
- Target
- Sympathetic
- L1 - L2
- Hypogastric plexus
- Pelvic viscera
Lumbar splanchnics
- Type of innervation
- Origin
- Synapse
- Target
- Sympathetic
- L1 - L2
- Inferior mesenteric ganglion
- Hindgut derivatives
Vagus nerve
- Type of innervation
- Origin
- Synapse
- Target
- Parasympathetic
- Brainstem medulla
- synapses at target organ
- Pharynx & larynx muscles, abdominal viscera
Pelvic splanchnics
- Type of innervation
- Origin
- Synapse
- Target
- Parasympathetic
- Anterior rami S2-S4
- synapses at target organ
- Hundgut derivatives (past splenic flexure)
Pudendal nerve
- Type of innervation
- Origin
- Synapse
- Target
- Somatic
- Anterior rami S2-S4
- none
- Pelvic muscles and anal sphincter
Autonomics diagram
What are the 6 different sphincters and what is their muscle type?
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Oesophagus neurovasculature. what is their innervation, arterial supply, venous drainage, lymphatics
Stomach neurovasculature. what is their innervation, arterial supply, venous drainage, lymphatics
Duodenum neurovasculature. what is their innervation, arterial supply, venous drainage, lymphatics
Jejunum and Ileum neurovasculature. what is their innervation, arterial supply, venous drainage, lymphatics
What is Celiac disease and its clinical presentations?
- Autoantibodies targetting TTG (tissue transglutaminase)
Clinical presentations: - Steatorrhea (foul smelling, floaty stools)
- Malabsorption symptoms -> weight loss
- abdom pain, diarrhoea, etc
Colorectal cancer clinical presentation
- Altered bowel habit
- rectal bleeding
- weight loss
- iron-deficiency anaemia
