Meissner's plexus(submucosal)
The nerves of the small intestines are derived from the plexuses of parasympathetic nerves around the superior mesenteric artery. From this source they run to the myenteric plexus (Auerbach's plexus) of nerves and ganglia situated between the circular and longitudinal muscular fibers from which the nervous branches are distributed to the muscular coats of the intestine. From this a secondary plexus, the plexus of the submucosa (Meissner's plexus, Submucous plexus, submucosal plexus) is derived, and is formed by branches which have perforated the circular muscular fibers. This plexus lies in the submucous coat of the intestine; it also contains ganglia from which nerve fibers pass to the muscularis mucosae and to the mucous membrane. The nerve bundles of the submucous plexus are finer than those of the myenteric plexus.
Auerbach's plexus
Part of the enteric nervous system, Auerbach's plexus (or myenteric plexus) exists between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract and provides motor innervation to both layers and secretomotor innervation to the mucosa.
It arises from cells in the Nucleus ala cinerea, the parasympathetic nucleus of origin for the tenth cranial nerve (Vagus), located in the medulla oblongata. The fibers are carried by both the anterior and posterior vagal nerves.
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Tubular Adenoma doesn't invade muscularis mucosa?
Villous stalk or polyp
All intestines have goblet cells
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Rule of 2's Meckel's diverticulum
- 2 inches long
- 2 feet from ileocecal valve
- 2 % of population
- commonly presents in first 2 yrs of life
- may have 2 types of epithelia(gastric/pancreatic)
Different than acquired diverticulum
- mucosa just pushed between muscle fibers
- has all three layers of GI, acquired diverticulum doesn't have all 3 layers
- Omphalomesenteric cord remnant
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Causes of GI bleed
- vascular ischemia
- diverticulitis
- AV malformation
in appendix,
neurotization -> gray patches -> obliterated appendix
epinephrine -> vasoconstriction; administered when GI bleed
coffee ground emesis(if upper GI bleed)
