Embryology Of Midgut

Question 1

List the derivatives of the midgut

Answer 1

Duodenum distal to the opening of the bile duct, caecum, appendix, ascending colon, right 1/2 - 2/3 of the transverse colon

Question 2

Midgut is supplied by which artery

Answer 2

Superior mesenteric artery

Question 3

As the midgut elongates it forms a — -shaped loop of the which projects into the umbilical cord
▪ Hence the midgut loop forms a physiological umbilical herniation occuring at the beginning of the —th week

Answer 3

As the midgut elongates it forms a u-shaped loop of the which projects into the umbilical cord
▪ Hence the midgut loop forms a physiological umbilical herniation occuring at the beginning of the 6th week

Question 4

▪ This loop has ——- and —— limbs – an ———-is attached to the apex of the loop where the 2 limbs join
▪ The tip of the loop connected with the yolk sac (by a Vitelline duct) persists till the end of —-th wk.

Answer 4

▪ This loop has a cranial (proximal) and caudal (distal) limbs – an omphaloenteric duct (yolk stalk) is attached to the apex of the loop where the 2 limbs join
▪ The tip of the loop connected with the yolk sac (by a Vitelline duct) persists till the end of 10th wk.

Question 5

▪ —- limb grows rapidly, forms intestinal loops
▪ — limb undergoes very little change except for developt of the cecal swelling (diverticulum) (the primordium of the cecum and appendix )

Answer 5

▪ Cranial limb grows rapidly, forms intestinal loops
▪ Caudal limb undergoes very little change except for developt of the cecal swelling (diverticulum) (the primordium of the cecum and appendix )

Question 6

▪ Caudal limb undergoes very little change except for developt of the ——-

Answer 6

▪ Caudal limb undergoes very little change except for developt of the cecal swelling (diverticulum) (the primordium of the cecum and appendix )

Question 7

▪ Cephalic limb forms:
▪ Caudal limb forms :

Answer 7

▪ Cephalic limb forms the distal part of duodenum, jejunum and part of ileum
▪ Caudal limb forms the lower portion of ileum, cecum, appendix, ascending colon and proximal 1⁄2-2/3 of transverse colon

Question 8

Rotation of midgut loop
▪ In the umbilical cord, the midgut loop rotates 90° counterclockwise around the axis of the —-
▪ Cranial limb is now on—- side
▪ Caudal limb is now on —- side
▪ During rotation cranial limb elongates and forms intestinal loops (primordia of jejunum and ileum)

Answer 8

Rotation of midgut loop
▪ In the umbilical cord, the midgut loop rotates 90° counterclockwise around the axis of the SMA
▪ Cranial limb—right
▪ Caudal limb—left
▪ During rotation cranial limb elongates and forms intestinal loops (primordia of jejunum and ileum)

Question 9

Return of Midgut to the
abdomen
▪ During the 10th week, the intestines return to the abdomen (reduction of midgut hernia)
▪ The small intestine returns first, as the large intestine returns it undergoes a further ——° counterclockwise rotation and occupies the —- side of the abdomen

Answer 9

Return of Midgut to the
abdomen
▪ During the 10th week, the intestines return to the abdomen (reduction of midgut hernia)
▪ The small intestine returns first, as the large intestine returns it undergoes a further 180° counterclockwise rotation and occupies the right side of the abdomen

Question 10

List the Factors responsible for
the retraction

Answer 10

▪ Regression of mesonephric kidney
▪ Reduced growth of liver
▪ Expansion of abdominal cavity

Question 11

List the Mesenteries of Intestinal
loops

Answer 11

Mesenteries of Intestinal
loops
▪ Mesentery proper
▪ Mesentery of ascending and
descending colon (dorsal mescolon)
▪ Appendix, lower end of cecum
▪ Transverse mesocolon

Question 12

Fixation of Intestinal loops
▪ The mesentery of the pry intestinal loops called the —— undergoes changes- rotation and coiling of the bowel
▪ As asc and desc colons obtain their definitive positions, their mesenteries press against the peritoneum of post abdominal wall- fusion
▪ After fusion, the asc and desc become ——-

Answer 12

Fixation of Intestinal loops
▪ The mesentery of the pry intestinal loops- mesentery proper undergoes changes- rotation and coiling of the bowel
▪ As asc and desc colons obtain their definitive positions, their mesenteries press against the peritoneum of post abdominal wall- fusion
▪ After fusion, the asc and desc become retroperitoneal

Question 13

Fixation of Intestinal loops

▪ The appendix, lower end of cecum, retain their mesenteries
▪ Transverse mesocolon fuses with the ———but maintains its mobility
▪ Mesentery of jejunoileal loops is first continous with that of the —— but changes line of attachment when the asc mesocolon fuses with the post abd wall.

when the asc mesocolon fuses with the post abd wall, the mesentery of the small intestine becomes — shaped and acquires a new line of attachment that passes from the —— junction to the —— junction

Answer 13

Fixation of Intestinal loops

Fixation of Intestinal loops

▪ The appendix, lower end of cecum, retain their mesenteries
▪ Transverse mesocolon fuses with the greater omentum but maintains its mobility
▪ Mesentery of jejunoileal loops is first continous with that of the ascending mesocolon but changes line of attachment when the asc mesocolon fuses with the post abd wall.

when the asc mesocolon fuses with the post abd wall, the mesentery of the small intestine becomes fan- shaped and acquires a new line of attachment that passes from the duodenojejunal junction to the ileocecal junction

Question 14

The cecum and appendix
▪ Primordium of the cecum and appendix called —— appears in —th week
▪ The appendix first arises from the —- end of the cecum, however with unequal growth of the wall of cecum it is located on the —- side

Answer 14

The cecum and appendix
▪ Primordium of the cecum and appendix- cecal swelling (diverticulum) appears in 6th week
▪ The appendix first arises from the distal end of the cecum, however with unequal growth of the wall of cecum it is located on the medial side

Question 15

Positional variations of the appendix
▪ As the ascending colon elongates, the appendix may pass post to the cecum (called the —— appendix) or colon (called the —— appendix).
▪ It may descend over the brim of the pelvis (called the —— appendix)
▪ In approx 64% of people it is located ——

Answer 15

Positional variations of the appendix
▪ As the ascending colon elongates, the appendix may pass post to the cecum (retrocecal appendix) or colon (retrocolic appendix).
▪ It may descend over the brim of the pelvis (pelvic appendix)
▪ In approx 64% of people it is located retrocecally

Question 16

Appendix is located retrocecally in how many % of people

Answer 16

64%

Question 17

Omphalocele
▪ Failure of the bowel to return to the body cavity from its physiological herniation during —-th to —th week.
▪ It is associated with other defects such as—-

Answer 17

Omphalocele
▪ Failure of the bowel to return to the body cavity from its physiological herniation during 6th to 10th week.
▪ It is associated with other defects such as cardiac anomalies, neural tube defects & chromosomal abnormalities.

Question 18

——— is the Failure of the bowel to return to the body cavity from its physiological herniation during 6th to 10th week.

Answer 18

Omphalocele is the Failure of the bowel to return to the body cavity from its physiological herniation during 6th to 10th week.

Question 19

Gastroschisis
▪ Protrusion of abdominal contents thru body wall directly into amniotic cavity not covered by —- or —-.
▪ Bowel may be damaged by exposure to ——.
▪ Defect is due to abnormal closure of body wall around the ———. Occurs lateral to the —- usually on the —- side.

Answer 19

Gastroschisis
▪ Protrusion of abdominal contents thru body wall directly into amniotic cavity not covered by amnion or peritoneum.
▪ Bowel may be damaged by exposure to amniotic fluid.
▪ Defect is due to abnormal closure of body wall around the connecting stalk. Occurs lateral to the umbilicus usually on the right.

Question 20

——— is the Protrusion of abdominal contents thru body wall directly into amniotic cavity not covered by amnion or peritoneum.

Answer 20

Gastroschisis is the Protrusion of abdominal contents thru body wall directly into amniotic cavity not covered by amnion or peritoneum..

Question 21

Umbilical Hernia
▪ Intestines return to abdominal cavity at 10th week, but herniate through an ——-
▪ A common type of hernia.
▪ Herniated contents are usually the — &——.
▪ The hernial sac is covered by —- & ——.
▪ It protrudes during —-, — or —— and can be easily reduced through—— at
▪ Surgery is performed at age of — to — years.

Answer 21

Umbilical Hernia
▪ Intestines return to abdominal cavity at 10th week, but herniate through an imperfectly closed umbilicus
▪ A common type of hernia.
▪ Herniated contents are usually the greater omentum &
small intestine.
▪ The hernial sac is covered by skin & subcutaneous tissue.
▪ It protrudes during crying, straining or coughing and can be easily reduced through fibrous ring at umbilicus.
▪ Surgery is performed at age of 3-5 years.

Question 22

—— is when Intestines return to abdominal cavity at 10th week, but herniate through an imperfectly closed umbilicus
▪ A common type of hernia.

Answer 22

Umbilical Hernia
▪ Intestines return to abdominal cavity at 10th week, but herniate through an imperfectly closed umbilicus
▪ A common type of hernia.

Question 23

Meckel’s diverticulum
▪ occurs in —% of people, —- feet away from Ileo-cecal valve, —- inches long.
▪ Persistence of —- forms: Meckel’s diverticulum or ileal diverticulum

Answer 23

Meckel’s diverticulum
▪ 2% of people, 2 -feet away from Ileo-cecal valve, 2 -inches long.
▪ Persistence of Vitelline duct forms: Meckel’s diverticulum or ileal diverticulum
▪ Other related structures are vitelline cyst, umbilical fistula or vitelline fistula and vitelline ligaments

Question 24

Another name for Meckel’s diverticulum

Answer 24

ileal diverticulum