Autonomics of Abdomen

Question 1

describe postganglionic sympathetics

Answer 1

• preaortic/prevertebral ganglia
  
  • at roots of major arteries branching from abdominal aorta
    
    • celiac
    • sup. mesenteric
    • inf. mesenteric
    • renal

Question 2

describe postganglionic parasympathetics

Answer 2

• in the GI:
  
  • synpase on the neurons of the submucosal (Meissner’s) and myenteric (Auerbach’s) plexus (all part of the enteric system)

Question 3

describe the sympathetic splanchnics (preganglionic) to GI

Answer 3

• greater splanchnic (T5-T9) synapses in the celiac ganglion
• lesser splanchnic (T10-11) synapses in the aortico-renal ganglion
• least splanchnic (T12) synpases in the renal plexus
• lumbar splanchnic (L1-L2) synapses in the intermesenteric and/or superior hypogastric plexus

Question 5

name the derivatives of the foregut

Answer 5

• pharynx and its derivatives
• lower resp. tract
• esophagus
• stomach
• duodenum to the major duodenal papilla
• liver, billary apparatus and pancreas

Question 6

name the derivatives of the midgut

Answer 6

• duodenum distal to the major duodenal papilla
• jejunum & ileum
• cecum & appendix
• ascending colon and right 2/3 of transverse colon

Question 7

name the derivatives of the hindgut

Answer 7

• left 1/3 of the transverse colon
• descending colon, sigmoid colon & rectum
• anal canal up to the pectinate line
• urinary bladder and most of urethra

Question 8

name the arterial supply of the foregut/midgut/hindgut

Answer 8

foregut (and spleen) = celiac a.

midgut = sup. mesenteric a.

hindgut = inf. mesenteric a.

Question 9

describe the nerves of the PS GI system

Answer 9

• vagus nerve (preganglionic)
  
  • supplies foregut and midgut
  • passes through celiac ganlgion to the periarterial plexus (around celiac trunk) to synapse in foregut
• pelvic splanchnics (S2-S4) (preganglionc)
  
  • hindgut
  • travels through inf. hypogastric plexus to inf. mesenteric plexus to synapse in hindgut

Question 10

review the nerve and blood supply of the gut

Answer 10

Question 11

describe the referred pain from the foregut structures

Answer 11

• perceived as epigastric/upper quadrant pain (T5-9)

Question 12

describe referred pain from the midgut structures

Answer 12

• perceived as periumbilical pain (T10-12)

Question 13

describe referred pain from the hindgut structures (up to the midpoint of sigmoid colon)

Answer 13

• perceived as lower quadrant/flank/groin/thigh pain (L1-2)

Question 14

describe referred pain from the hindgut structures (after the midpoint of sigmoid colon)

Answer 14

• perceived as perineal pain (S2-4)

Question 15

describe the reffered pain of appendicitis

Answer 15

• visceral afferents for pain from the appendix follow the sympathetic supply back to the T10 spinal segment
  
  • early appendicitis is felt as poorly localized, periumbilical pain (T10-12)
• in later stages, the appendix conacts and irritates the parietal peritoneum in the right iliac fossa

Question 16

describe the referred pain of the liver and gall bladder

Answer 16

• visceral afferents for pain from the gallbladder and billary apparatus follow sympathetics to T7-9
  
  • pain in the epigastric area
• patients may also feel pain/discomfort at the inferior angle of the scapula (referred to T7-9)
• pain in shoulder from phrenic nerve because of inflammed gallbladder