Gastrointestinal Arteries and Nerves - Ashley Flashcards
Mneumonic for where structures enter the abdomen
I ate 10 eggs at 12
IVC - 8
Esophagus - 10
Aorta - 12
Abdominal aorta
Begins at T12
Retroperitoneal
Terminates at L4
-bifurcates into L and R common iliac arteries
Where does the thoracic duct drain?
Into the LEFT subclavian vein
AAA
Balloon like dilation of aorta when media (usually) weakens
Usually below renal arteries and above aortic bifurcation
Primarily due to atherosclerosis
Unpaired branches of aorta
Supply GI structures and branch anteriorly
-Celiac trunk, superior mesenteric, inferior mesenteric, median sacral a.
Paired branches of aorta
Supply non-GI structures and branch laterally
-inferior phrenic, testicular/ovarian, suprarenal, renal, common iliac
Innervation of abdominal viscera
Nerve plexi Networks containing symp, parasymp, afferent nerve fibers and respective ganglia Some interconnected Named for nearest branch of aorta -celiac, sup mes, inf mes
Where do presynaptic fibers aries from?
Gray matter of spinal cord at T5-L2, L3
Conveyed via abdominopelvic splanchnic nerves
What is the main source of presynaptic sympathetic fibers to abdominal viscera?
Greater splanchnic
T5-9
Others contribute - Lesser (T10-11) and Least (T12)
Pelvic splanchnic n.
Derive from anterior rami of S2-4
NOT associated with sympathetics
Innervation beyond left colic flexure
What provides innervation up to left colic flexure?
Ant and post vagal trunks
-convey presynaptic and visceral afferent reflex fibers to abdominal aortic plexuses and periarterial plexuses
2 Principle plexuses of enteric nervous system
- Myenteric plexus - motility
2. Submucosal plexus - secretions, blood flow, absorption
Celiac trunk
3 branches - L gastric, splenic, common hepatic
Common hepatic a. branches into these two arteries?
- Proper hepatic –> R gastric –> R and L hepatic
2. Gastroduodenal a. –> R gastro-omental and superior pancreaticoduodenal
2 branches of splenic artery?
Short gastric
L gastro-omental
What is contained within the hepatoduodenal ligament?
Portal triad
-bile duct, proper hepatic artery, portal vein
What forms the bile duct?
Common hepatic duct (liver) Cystic duct (gallbladder)
Blood supply to liver?
Proper hepatic a. - oxygenated –> divides into L and R hepatic
Portal v. - deoxygenated, nutrient rich blood
Portal vein is formed by union of?
Splenic v and superior mesenteric v
What drains the liver?
Hepatic vv.
Blood supply to pancreas
Celiac a.
Superior mesenteric a. - gives off branches to ‘free’small intestine
- *Emerges from aorta posterior to the neck of the pancreas
- enters THE mesentery and runs between layers
Superior mesenteric artery branches
- Inferior pancreaticoduodenal a.
- Jejunal a. - long vasa recta, simple arcades
- Ileal a. - short vasa recta, complex arcades
What makes ileum different?
Short vasa recta, complex arcades
Less vascularized
Fewer plicae circulares are shorter or absent
Superior mesenteric artery branches to large intestine
Middle colic a.
Right colic a
Marginal a.
Ileocolic a.
What joins to form the portal vein
Superior mesenteric vein
Splenic vein
–posterior to the neck of the pancreas
Inferior mesenteric artery
Supplies derivatives of the hind gut (distal 1/3 of transverse colon to upper portion of rectum)
Branches - L colic, Sigmoid a, superior rectal a, marginal a
Internal hemorrhoids
Prolapse and breakdown of muscularis mucosae
No pain
External hemorrhoids
Thromboses in veins of external rectal venous plexus from increased intra-abdominal pressure
Innervated by inferior anal nerves —PAIN
Causes of ischemic bowel
- Embolus - blood clot form heart or main vessels block an artery supplying the intestine
- Arterial thrombosis - a. become narrowed due to atherosclerotic disease
- Venous thrombosis - v. carrying blood away form intestines may become blocked by blood clots
Volvulus most often occurs where?
In the sigmoid portion of the large intestine
