Session 3 - Embryology II / Anatomy

Question 1

During the 6th week, the very speedy growth of the midgut results in..

Answer 1

Herniation of the primary intestinal loop into the umbilicus

Question 2

What does the primary intestinal loop rotate around?

Answer 2

SMA

Question 3

What are the starting positions for rotation of the primary intestinal loop?

Answer 3

Cranial end (future SI) is superior, caudal end (future TC) is inferior

Question 4

By how much does the primary intestinal loop rotate and in which direction

Answer 4

Anticlockwise 270 degrees

Question 5

What is incomplete rotation

Answer 5

Only rotates one rotation, gets stuck at stage with SI on right and colon on left

Question 6

What is reversed rotation

Answer 6

One clockwise rotation and TC ends up behind the duodenum

Question 7

Midgut defects are associated with…

Answer 7

volvulus

Question 8

What is the vitelline duct

Answer 8

Connects primary intestinal loop to yolk sac

Question 9

Most common congenital SI abnormality?

Answer 9

Meckel’s diverticulum (2% of pop)

Question 10

What is Meckel’s diverticulum

Answer 10

Outpouching of vitelline duct that has not fully regressed so it looks like a bulging out of the SI. Often has stomach or pancreas cells in it, produce things that form ulcers, it bleeds.

Question 11

Name three abnormalities associated with the vitelline duct

Answer 11

Vitelline cyst, vitelline fistula, Meckel’s diverticulum

Question 12

What is a vitelline cyst

Answer 12

Cystic remnant of vitelline duct, has fibrous band connecting to abdo wall

Question 13

What is a vitelline fistula

Answer 13

Open vitelline duct, communciation between SI and umbilicus

Question 14

What is pyloric stenosis (+one symptom)

Answer 14

Hypertrophy of pyloric sphincter, projectile vom

Question 15

Why is recanalisation important in gut growth

Answer 15

During gut growth it can grow so fast that the lumen disappears (in oesophagus, bile duct and SI). Need recanalisation to restore it- if wholly/partly unsuccessful then atresia or stenosis

Question 16

Where does atresia/stenosis occur most commonly after failed recanalisation?

Answer 16

Duodenum

Question 17

Compare contrast omphalocele and gastroschisis

Answer 17

Omphalocele- herniation of midgut within parietal peritoneum into umbilical cord persists outside the body, covered with sac
Gastroschisis- congenital defect in abdominal wall so guts herniate out, have no sac and in contact with amniotic fluid so get oedematous and inflamed
Omphalocele is persistance of physiological herniation, whereas gastroschisis is a defect, failure of abdo wall to fuse.

Question 18

What’s an umbilical hernia?

Answer 18

Gut pushes through weak region near umbilicus, but covered with skin and subcute tissue, doesn’t get far

Question 19

What divides the anal canal into 2 parts?

Answer 19

The pectinate line

Question 20

Another name for the anal pit..

Answer 20

Proctodeum

Question 21

Why do above and below the pectinate line have different features

Answer 21

One comes from the proctodeum (ectoderm) and one comes from the hindgut (endoderm)

Question 22

What is the blood supply below and above the pectinate line

Answer 22

Above is IMA, below is pudendal artery

Question 23

Describe epithelium above and below pectinate line

Answer 23

Above is columnar, below is stratified

Question 24

Describe nerve supply above and below pectinate line

Answer 24

Above is pelvic parasympathetics, below is pudendal nerve

Question 25

What can be felt above and below pectinate line

Answer 25

Above is stretch, below is touch pain temp

Question 26

Lymphatics above and below pectinate line

Answer 26

Above is internal iliac nodes, below is superficial inguinal nodes

Question 27

Where does foregut, midgut and hindgut pain localise to?

Answer 27

Epigastric, periumbilical, suprapubic

Question 28

Tell me midgut and hindgut parasympathetic supply

Answer 28

Midgut is vagus, hindgut is pelvic