GI Embryology Flashcards
the cranial end of the primordial gut is initially closed by the ______ a the ______
the caudal end is initially closed by the ______ at the ______
oropharyngeal membrane at the stomodeum
cloacal membrane at the proctodeum
the primordial gut is derived from (2)
endoderm (most of gut, epithelium, and glands)
splanchnic mesenchyme (muscle, connective tissue)
what are the regional differences (3) of the primordial gut, and what genes are they established by?
foregut, midgut, and hindgut
Sonic hedge hog (Shh) and Indian hedge hog (Ihh) genes
Derivatives (7) of the foregut and their blood supply*
*except which 3?
primordial pharynx lower respiratory system esophagus stomach duodenum (up to bile duct) liver and biliary apparatus pancreas
supplied by celiac trunk
*except for pharynx, lower resp., and most of esophagus
esophagus is intially formed by week ___ and is recanalized during week ___
7
8
anomaly that is a blockage of the esophageal lumen - can be a result of failure of recanalization
esophageal atresia
in stomach development, a dilation in the foregut appears in week ___ and enlarges __________ (direction)
4
ventrodorsally
_____ border of stomach grows quicker leader to _________ of the stomach
dorsal
greater curvature
stomach enlarges and rotates ___________, causing these 4 changes
90 degrees clockwise
lesser curvature moves right, greater moves left
cranial end moves left, slightly inferior
caudal end moves right, slightly superior
vagus nerve innervation
anterior wall of stomach is innervated by ____
posterior wall of stomach is innervated by ______
(steering wheel is top-down view)
left vagus nerve
right vagus nerve
anomaly caused by hypertrophy of pyloric muscles, obstructing food
congenital hypertrophic pyloric stenosis
duodenum develops form which regions of primordial gut?
caudal part of foregut and cranial part of midgut
blood supply to duodenum (2)
celiac trunk
superior mesenteric
duodenum rotates with stomach to lie
right and retroperitoneally
anomaly caused by incomplete recanalization of duodenum
duodenal stenosis
complete occlusion of duodenum; amniotic fluid absorption is prevented; presence of “double bubble sign” on ultrasound
duodenal atresia
derivatives of midgut (5) and blood supply
small intestine cecum appendix ascending colon right 2/3 of transverse colon
supplied by superior mesenteric artery
what is the midgut loop?
ventral u-shaped loop that projects into the proximal part of the umbilical cord due to limited room in abdominal cavity
cranial limb of midgut loop forms:
caudal limb of midgut loop forms:
small intestine with rapid growth - jejunum and ileum
cecal diverticulum and appendix
physiological umbilical herniation (midgut loop) happens in what week?
6
midgut loop rotates __________ around __________
bringing cranial limb to the ____ and caudal limb to the _____
90 degrees counterclockwise
superior mesenteric artery
left; right
when do intestines return to abdomen?
10 weeks
back in the abdomen, the large intestine continues __________ rotation to form ________
180 degree counterclockwise
right side of abdomen
midgut anomaly:
herniation of abdominal contents into umbilical cord; failure of body walls to fuse at umbilical ring
congenital omphalocele
midgut anomaly:
umbilicus not closed; intestines herniate; appears during crying or straining
umbilical hernia
midgut anomaly:
remnant of proximal portion of omphaloenteric duct along border of ileum; can become inflamed and symptoms mimic appendicitis
Ileal diverticulum - Meckel’s diverticulum
“split stomach”
viscera protrude into the amniotic cavity
Gastroschisis
cecum develops as a dilation of the _____
caudal midgut loop
appendix first starts as
a small diverticulum off cecum
variations in final locations of appendix (3)
medial side
retrocecal
rectrocolic
derivatives of hindgut (5) and blood supply
left 1/3 of transverse colon descending colon sigmoid colon rectum superior part of anal canal
supplied by inferior mesenteric artery
what is the cloaca
expanded end of hindgut before division into rectum, bladder, and primordial genitalia
in partitioning of the cloaca, the _______ grows caudally to meet the ________ and form the ______ body
urorectal septum
cloacal membrane
perineal
cloacal partitioning divides cloaca into (2)
anal canal dorsally
urogenital sinus ventrally
superior 2/3 of anal canal derived from _____
inferior 1/3 of anal canal derived from ______
hindgut
proctodeum
what is the pectinate line?
irregular line of tissue where the two regions of the anal canal meet
hindgut anomaly:
dilated part of colon; failure of peristalsis preventing intestinal movement
congenital megacolon (Hirschsprung disease)
hindgut anomaly:
thin layer of tissue separates anal canal from exterior
membranous atresia of anus
aka
imperforate anus
