Formation of Face - Weeks 3-5

Question 1

What is the crown-rump length in the 3rd week?

Answer 1

3mm

Question 2

What is the crown-rump length in the 8th week?

Answer 2

30mm

Question 3

The ____ appears in the 3rd week and becomes the nasal and oral cavities between the 6th and 8th weeks.

Answer 3

Stomodeum

Question 4

What are the 3 boundaries of the stomodeum?

Answer 4

Superior - Frontal prominence
Inferior - Cardiac plate
Posterior - Buccopharyngeal membrane

Question 5

In week 4, the first branchial arch becomes what?

Answer 5

R and L maxillary facial processes

R and L mandibular facial processes

Question 6

_____ and _____ appear and disappear in the 4th week.

Answer 6

Branchial arches and clefts

Question 7

What is the place where the upper maxillary and lower mandibular processes meet at either side of the stomodeum?

Answer 7

Commissura labiorum oris

Question 8

Branchial pouch 1 becomes what?

Answer 8

external auditory meatus

Question 9

In the fourth week the cardiac plate is replaced as the inferior boundary of the stomodeum by what?

Answer 9

the 2 mandibular facial processes

Question 10

In the fourth week the 2 maxillary facial processes become what boundaries of the stomodeum?

Answer 10

posteriolateral

Question 11

In the fourth week 2 nasal pits appear within what?

Answer 11

the frontal prominence

Question 12

After the appearance of nasal pits the frontal prominence becomes 3 processes, what are they?

Answer 12

median nasal facial process

R and L lateral nasal processes

Question 13

Nasal pits deepen to become what?

Answer 13

nasal ducts that open into the stomodeum, the ducts become nostrils that open into nasal cavities during formation of nasal and oral cavities

Question 14

During the 4th week, how many facial processes are formed by the first branchial arch and the frontal prominence?

Answer 14

7

Question 15

What does the median nasal process become?

Answer 15

midline of nose

philtrum of upper lip

Question 16

What do the lateral nasal processes become?

Answer 16

lateral sides and ala of nose

infraorbital part of face

Question 17

What do the maxillary processes become?

Answer 17

upper part of cheeks

lateral parts of upper lip

Question 18

What do the mandibular processes become?

Answer 18

lower part of cheeks
lower lip
chin

Question 19

In week 4, arch II becomes an embryonic fold of tissue called what?

Answer 19

operculum, it covers arches III and IV and clefts II, III, IV, it becomes the side of the neck below the external auditory meatus

Question 20

Merging takes place between facial processes during what?

Answer 20

facial formation

Question 21

If the maxillary facial process or processes do not merge with the median nasal facial process by the 5th week, what occurs?

Answer 21

unilateral or bilateral clefting of the upper lip occurs

Question 22

Although rare, if the mandibular processes do not merge with each other by the 5th week, what occurs?

Answer 22

clefting of the lower jaw

Question 23

The buccopharyngeal membrane ruptures allowing what?

Answer 23

An opening into the foregut which becomes the nasal and or pharynx

Question 24

The buccopharyngeal membrane is the site of what in the adult?

Answer 24

Anterior pillar fauces