Midgut & Hindgut Embryo Flashcards
Adult derivatives of the mid-gut
duodenum distal to the common bile duct (2-4 part), jejunum, ileum, cecum, appendix, ascending colon, proximal transverse colon
blood supply to the midgut
SMA
Midgut herniates into
the umbilical cord, forms a u-shaped loop. The two ends of the loop are connected by the dorsal mesentary.
When does mid-gut herniation happen?
Beginning of week 6
Two parts of mid-gut loop, which grows faster
Cranial and Caudal, the Cranial grows faster and has many folds. These folds become the small intestine. This growing also causes a 90 degree counterclockwise loop, so the loop now sits in a transverse plane.
When does the midgut return to the abdomen
week 10. During the return the small intestine becomes central and the large intestine becomes peripheral.
Rotation of small intestine as it returns into the abdomen
180 degree rotation, causes the large intestine to cross over the small intestine. In adult the transverse colon crosses anterior to the small intestine.
Fixation of organs
What causes things to be intra/retro peritoneal
Line of attachment of small intestine mesentary
Starts Left upper quadrant at duodenaljejunal junction, ends Right Lower Quadrant at ileocecal junction
When does decal diverticulum appear, what is it primordial of, where does it appear
Week 6, primordial of cecum and appendix.
Appears on the antimesenteric border.
How does appendix attach
In variable positions to the cecum
Hindgut derivatives
Left transverse colon, descending colon, sigmoid colon, rectum, superior portion of anus, epithelial lining of urinary bladder, most of the urethra
Blood supply of hindgut
IMA
What is the cloaca
Expanded distal hindgut, lined with endoderm. The allantois empties into the cloaca.
Two components of cloacal membrane
endoderm of cloaca, ectoderm of proctodeum (anal pit)
