Nerves & Vessels of the Abdomen Flashcards
The abdominal aorta divides into iliac arteries at
L4
Anterior branches of the abdominal aorta supply
GIT & derivatives
Lateral branches of the abdominal aorta supply
paired viscera (kidneys, adrenals, gonads)
Posterior branches of the abdominal aorta supply
paired posterior structures, diaphragm, and posterior abdominal wall
What are the 3 anterior (unpaired) branches of the AA?
celiac trunk (T12, upper border of pancreas)
superior mesenteric artery (L1, 1cm below celiac trunk)
inferior mesenteric artery (L3, inferior border of 3rd/hz part of duodenum)
The coeliac trunk supplies
foregut derivatives:
abdominal oesophagus, stomach, liver, gallbladder, pancreas, spleen, duodenum up to major duodenal papilla
What does the SMA supply?
midgut derivatives:
duodenum from major duodenal papilla, jejunum, ileum, appendix, caecum, ascending colon, most of the transverse colon up to near the splenic flexure
What does the IMA supply?
hindgut derivatives:
transverse colon just proximal to splenic flexure, descending colon, sigmoid colon, rectum, and top of the anal canal
What are the 3 branches of the celiac trunk?
splenic artery (L)
left gastric artery (L, superior and smaller than splenic)
common hepatic (R)
What does the splenic artery supply?
main:
- spleen
- pancreas
gastric:
- short gastric arteries (L fundus & greater curvature)
- L gastroepiploic (greater curvature)
What does the L gastric artery supply?
- oesophageal branches to cardio-oesophageal junction (abdominal oesophagus)
- lesser curvature of stomach
What does the common hepatic artery supply?
- divides into proper hepatic artery (liver via portal triad)
- divides into R & L hepatic arteries to the respective functional halves of the liver
- RHA (normally, or PHA) gives off cystic artery to the gallbladder
- gives off right gastric artery to lesser curvature of stomach
- and gastroduodenal artery
- first part of duodenum (bleeds in peptic ulceration)
- superior pancreaticoduodenal artery to head of pancreas
- right gastroepiploic artery to greater curvature of stomach
The SMA supplies
- inferior pancreaticoduodenal artery to distal duodenum
follows route of the mesentery (DJ flexure to ileocecal valve, across 3rd part of duodenum, aorta, IVC, lumbar VC, R psoas w/R ureter):
- L branches to jejunum and ileum
- create vascular arcades and vasa recta
- jejunum - few arcades, long vasa recta
- ileum - multiple arcades, short vasa recta
- R branches to colon (colic arteries), contribute to marginal artery
- iliocolic to beginning of colon
- right colic to ascending colon
- middle colic to transverse colon (up to where IMA takes over, just before splenic flexure)
What does the IMA supply?
- heads down and L to L iliac fossa (LLQ)
- gives off colic branches:
- left colic to rest of transverse colon & descending colon
- sigmoid artery to the sigmoid colon
- then becomes superior rectal artery before passing into the pelvis
The portal venous system drains
GIT (pancreas, gallbladder, spleen)
SMV + splenic vein (w/ IMV)
everything supplied by the coeliac trunk, SMA, and IMA except the liver
What comprises the (hepatic) portal vein?
IMV drains into splenic vein
splenic vein joins SMV @ L2
forms portal vein behind neck of pancreas
What are the five sites of portosystemic anastamoses?
- lower/abdominal oesophagus @ cardiac orifice (can tear w/vomiting)
- tributaries of L gastric vein (portal) & tributaries of azygous vein (caval/systemic)
- inferior GIT/anus (haemorrhoids)
- superior rectal veins (portal) & lower and inferior rectal veins (caval/systemic)
- anterior abdominal wall (caput medusa)
- cutaneous veins (cava/systemic) & tributaries of portal vein (portal)
- posterior abdominal wall
- retroperitoneal viscus (portal) w/back to posterior abdoiminal wall (caval/systemic)
- bare area of liver
- liver (caval) on diaphragm (portal)
Abdominal viscera are innervated by
ANS
Foregut derivatives are innervated by
T6-T9
Midgut derivatives are innervated by
T8-T12
Hindgut derivatives are innervated by
T12-L2
Preganglionic sympathetic fibres to the abdominal viscera are derived from
T6-L2
Sympathetic ganglion to the abdomen cluster around
unpaired branches of AA and renal arteries
Parasympathetic innervtation to the abdomen comes from
vagus (foregut and midgut), pelvic splanchnics (hindgut)
Parasympathetic innervation to the foregut and midgut is by
vagus
Parasympathetic innervation to the hindgut comes from
pelvic splanchnics (S2-4)
Visceral afferents of the abdomen run
- same spinal cord segment as sympathetic innervation up to mid sigmoid colon
- same spinal cord segment as parasympathetic innervation beyond the sigmoid colon
What structures refer pain to the midline of the anterior abdominal wall (dermatomes T6-L2)?
afferent fibres from unpaired abdominal viscera proximal to the mid-sigmoid colon
What structures refer pain to the perineal region (dermatomes S2-4)?
afferetn fibres from mid-sigmoid colon downward
Pre-aortic lymph nodes drain
anterior to the AA around the unpaired branches (celiac, SMA, IMA) and receive drainage from the structures they supply
Para-aortic lymph nodes drain
R & L aorta, drain structures supplied by the sides and back of AA (posterior abdominal walls, kidneys, adrenals, gonads)
+ pelvis and lower limb
What three lymphatics drain into the cisterna chyli?
intestinal lymph trunk from pre-aortic LNs
R & L lumbar lymphatic trunks
Where is the cisterna chyli?
adjacent to the aortic hiatus @ T12
What is the course of the thoracic duct?
- cisterna chyli
- traverse diaphragm w/AA thru crura @ T12
- posterior to oesophagus
- crosses L at T4-T5
- empties at junction of left IJV and left subclavian vein
The SMV drains
most of the gut from the 3rd part of the duodenum down to ~splenic flexure
The IMV comes off the
splenic vein
