The intestines Flashcards
Location of the foregut
Ends after entry of common bile duct into duodenum
Location of the midgut
Ends 2/3 of the way along transverse colon
Location of the hindgut
Ends halfway down the anal canal
Midgut mesentery
The mesentery attaches to posterior abdominal wall
Supplied by superior mesenteric artery
From DJF to ICJ, 15 cm long
Small intestine
6m Duodenum (1st part intraperitoneal) Jejunum (intraperitoneal) Ileum (intraperitoneal) From pyloric sphincter to ileocaecal junction Peristalsis and segmentation
The duodenum
In umbilical region from transpyloric plane
Ascending segment, smooth mucosal wall
Descending segment, pancreatic bile duct
Horizontal, behind superior mesenteric artery
Ascending, DJF held up by suspensory ligament of Treitz
Plicae circulars only found in 2, 3 ,4
Brunners glands found here neutralize stomach acid
Suspensary ligament of Treitz
Holds up DJF from right crus of diaphragm
Parts and relations of the duodenum
R kidney behind descending duodenum
Pancreas wrapped in curvature of duodenum
Superior mesenteric artery comes over duodenum
Aorta and VC behind duodenum and pancreas
Openings into duodenum
Accessory duct leads into minor papilla
Common bile duct and main pancreatic duct leads into major papilla/ampulla of Vater
Jejunal mucosal layers
Plicae circularis, mucosa
Submucosa
Muscularis externa (circular, longitudinal)
Serosa
Long vasa recta, no anastomoses
Simple arterial arcades
V little fat
Ileal mucosal layers
No plicae circularis, Peters patches instead
Submucosa
Muscularis externa (circular, longitudinal)
Serosa
Short vasa recta
Complex arterial arcades, many anastomoses
Fat filled mesentery
Lymphatics of the intestines
Mesenteric nodes, joins pre aortic nodes (coeliac, superior, inferior mesenteric)
Join cistern chili via para aortic, enters thoracic duct and L jugular, subclavian
Features of the large intestine
Teniae coli
Haustra
Epiploic appendages
Teniae coli
3 longitudinal strips of muscle
Thickening of longitudinal muscle of musclaris externa
Maintain muscle tone, cause haustra
Haustra
Saclike divisions
Epiploic appendages
Mental appendices
Fat filled pouches
Extensions of peritoneum
Large intestine function
Absorption of water and electrolytes
Mass peristaltic movements => rectum
Residue moves through colon in 12-24
Caecum and ascending colon
Blind end of caecum into appendix
Expanded plicae circularis, forms ileocaecal valve
Retroperitoneal caecum, intraperitoneal appendix
The appendix
Has its own mesentery
Can be in variable locations
Opening associated with teniae coli
Appendicitis
Pain initially in umbilical region
When infection moves to parietal peritoneum, pain moves to R iliac
Colon and colic flexures
R colic/hepatic flexure and L colic/splenic flexure
Transverse and sigmoid colon, intraperitoenal
Ascending, descending colon, retroperitonela
Mesenteric vessels, superior mesenteric
Jejunal ileal
Ileocolic, appendicular
R colic
Middle colic
At L1
Veins match mesenteric arteries
Mesenteric vessels, inferior mesenteric
L colic
Sigmoidal
Superior rectal
At L3
Veins match mesenteric arteries
Sympathetic innervation of foregut, midgut, hindgut
- Roots
- Preganglionic nerve
- Sympathetic ganglion
Foregut
- T5-T9
- Greater splanchnic nerve => celiac sympathetic ganglia
Midgut
- T10-T12
- Lesser and least splanchnic nerve => superior mesenteric ganglia
Hindgut
- T12-L2
- Lumbar splanchnic nerve => inferior mesenteric ganglia
Specific areas of innervation of the bowels
Duodenum T8 Jejunum T9 Ilium T10 Asc colon T11 Desc colon T12 Rectum and anus L1-2
Referred abdominal pain
Foregut, epigastric, ventral and dorsal
Midgut, umbilical
Hindgut, superopubic
Due to visceral pain being referred via sympathetic nerves
Parasympathetic innervation of the foregut, midgut, hindgut
- Preganglionic nerves
- Parasympathetic ganglion
Foregut
-Vagus => Intrinsic ganglia
Midgut
-Vagus => Intrinsic ganglia
Hindgut
-Pelvic splanchnic (S2-4) => Intrinsic ganglia
