Innervation
Parasympathetic innervation of the gut promotes peristalsis while it’s sympathetic innervation promotes vasoconstriction and inhibits peristalsis and digestion.
The enteric nervous system is the neuronal circuitry of the gastrointestinal wall and consists of the following:
Meissner’s plexus in the submucosa
Myenteric (Auerbach’s) plexus between the muscularis externa layers
Parasympathetic Innervation
The anterior and posterior vagal trunks are continuations of the right and left vagus nerves that emerge from the esophageal plexus. The anterior and posterior vagal trunks innervate foregut and midgut structures.
Pelvic splanchnic nerves are derived directly from the anterior rami of S2-S4 spinal nerves
Sympathetic Innervation
Splanchnic nerves include:
Greater splanchnic nerves (T5-T9) - celiac ganglia
Lesser splanchnic nerves (T10-T11) - superior mesenteric ganglia
Least splanchnic nerves (T12) - aorticorenal ganglia
Lumber splanchnic nerves (L1-L2/3) - inferior mesenteric and superior hypogastric plexus
Pain Afferents
Accompany sympathetic innervation:
Foregut T6-T9 - epigastric dermatome
Midgut T8-T12 - umbilical dermatome
Hindgut T12-L2 - hypogastric dermatome