Umbilical Anatomy

Question 1

The umbilical cord is the connection between the _____ and the _____

Answer 1

Embryo (fetus); placenta

Question 2

What are the components of the umbilical cord?

Answer 2

ONE umbilical vein
TWO umbilical arteries
Urachus
Wharton’s jelly

Question 3

What is the urachus?

Answer 3

Extension of the allantoic sac, from the apex of the bladder to the middle ligament of the bladder

Question 4

What is Wharton’s jelly?

Answer 4

Mesenchymal cells and stroma surrounding the structures of the umbilical cord; good source of stem cells for research

Question 5

Describe the location and function of the two umbilical arteries:

Answer 5

From internal iliac arteries; run through lateral ligaments of bladder to umbilicus
Carry deoxygenated, waste laden blood back to placenta

Question 6

Describe the location and function of the single umbilical vein:

Answer 6

Left vein; courses in the umbilical cord into the abdomen then cranially in the falciform ligament to the liver

Question 7

Describe what the remnants of the umbilical vessels become:

Answer 7

1. Umbilical vein: round ligament of the liver (runs in the free edge of the falciform ligament)
2. Umbilical arteries: Right & left round ligaments of the urinary bladder; runs in the free edge of the lateral ligaments of the bladder

Question 8

What is the cloaca?

Answer 8

Expanded caudal part of the hindgut caudal to the origin of the allantois

Question 9

What is the urorectal septum?

Answer 9

A wedge of mesoderm in the angle between the allantois & the hindgut

Question 10

Describe the cranial vesicular part of the urogenital sinus:

Answer 10

Cranial and largest part of the urogenital sinus, becomes the urinary bladder, continuous with the allantois

Question 11

Describe the function and development of the urachus:

Answer 11

Lumen of the allantois becomes obliterated, the urachus connects the apex of the bladder to the umbilicus and becomes the median ligament of the bladder

Question 12

Describe a patent urachus:

Answer 12

Failure of the allantoic stalk to close off in late fetal life; opens at the umbilicus and shows dribbling of urine

Question 13

Fecal material or meconium at the umbilicus indicates what anomaly:

Answer 13

Vitelline fistula

Question 14

Describe an umbilical hernia:

Answer 14

The protruding viscera are covered with normal skin (attenuated skin)

Question 15

Describe an omphalocele:

Answer 15

GIT herniation into the umbilical cord; herniated viscera are covered by a 3-layer membrane of peritoneum, Wharton’s jelly, and amnion
Due to failure of herniated intestine to return

Question 16

Describe gastroschisis:

Answer 16

Due to failure of the recti muscles to approximate in the midline after the return of intestine into the abdomen
Herniated viscera have no sac/cover and directly contact the amniotic fluid

Question 17

What is the difference between omphalocele and gastroschisis?

Answer 17

Omphalocele is a GIT defect where it fails to retract into the abdomen after the physiological hernia
Gastroschisis is a body wall defect, where the lateral body folds fail to fuse

Question 18

Describe what happens if the urorectal septum does not partition the hindgut properly

Answer 18

A newborn ends up with various types of fistulae (rectovaginal fistula)

Question 19

What is a urachal fistula?

Answer 19

Due to nonobliteration of the urachus
Urine passes out of the patent urachus to the umbilicus thus forming a congenital urinary umbilical fistula

Question 20

What is a urachal cyst?

Answer 20

Part of the urachus may remain non-obliterated leading to the formation of a cyst inside the abdomen

Question 21

Describe a urachal sinus:

Answer 21

The proximal part of the urachus is fibrosed while its distal part remains patent
Leads to the development of a sinus which discharges serous fluid through the umbilicus

Question 22

What is polyhydramnios?

Answer 22

Increased amniotic fluid; results if the fetus can not swallow due to GIT obstruction or neuro defect

Question 23

What is the difference between allantoic fluid and amniotic fluid?

Answer 23

Allantoic fluid: appears more urine-like in mid gestation as the developing kidneys from urine and send to the allantois
Amniotic fluid: Becomes more colorless and mucoid in late gestation (to lubricate at parturition)

Question 24

What is Oligohydramnios?

Answer 24

Decreased amniotic fluid, results if kidneys do not develop normally