L1

Question 1

During fourth embryonic week

Merging, not

Answer 1

Note: merging, not fusing, takes place between facial processes.

Question 2

4th embryonic week: The groove seen in the image between maxillary and median nasal processes is gradually

Answer 2

eliminated

Question 3

If the maxillary process or processes do not merge with the median nasal process by the 5th embryonic week,

Answer 3

unilateral or bilateral clefting of the upper lip occurs

Question 4

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

Answer 4

clefting of the lower jaw occurs

Question 5

End of week 4: Groove between

Answer 5

median and maxillary processes is still evident:

its length is lessened and median process is narrower

Question 6

Merging of facial processes complete by

Answer 6

y 5th embryonic week. If merger is not completed by this week, facial clefts occur

Question 7

Review of the fate of the 3 boundaries of the stomodeum:

Frontal prominence:

Answer 7

after the appearance of nasal pits becomes:

         * right and left lateral nasal facial processes
         * median nasal facial process

Question 8

Review of the fate of the 3 boundaries of the stomodeum:

Cardiac plate:

Answer 8

*replaced by the mandibular facial processes during 4th week IU

Question 9

Review of the fate of the 3 boundaries of the stomodeum:

Buccopharyngeal membrane

Answer 9

*ruptures in 4th week allowing opening to the foregut that becomes the nasal and oral pharynx
Note: the buccopharyngeal membrane is the site of the pillar of fauces

Question 10

Boundaries of Stomodeum (S):

3rd embryonic week

Answer 10

Superior: 1 = Frontal prominence

Inferior: 2 = Cardiac plate

Posterior 3 = Buccopharyngeal membrane

Question 11

Tongue : Appearance and Formation during

Answer 11

fourth embryonic week.

Four lingual swellings appear during the 4th embryonic week along the ventral, inside surface
of mandibular process of branchial arch I, II and III. During this same 4th week the buccopharyngeal membrane ruptures and, the 4 lingual swellings merge to become the t o n g u e

Question 12

Fate of 4 lingual swellings during 4th embyronic week:

Answer 12

Position of the 4 lingual swellings along the front wall of the pharynx and their
contributions to the t o n g u e:
Tuberculum Impar and 2 Lateral lingual swellings become anterior two - thirds of tongue
Copula becomes posterior third or root of tongue

Question 13

Copula becomes

Answer 13

posterior third or root of tongue

Question 14

The stomodeum will begin to partition

into oral and nasal cavities in the following

Answer 14

6th embryonic week:

Question 15

Fifth Embryonic Week

Answer 15

Appearance of structures within the stomodeum that enter into formation of palate:
Primary palate: Nasal septum: Palatine folds or shelves:

Question 16

Primary palate arises from

Answer 16

inner surface of median nasal facial process

Question 17

Nasal septum arises from

Answer 17

primary palate

Question 18

Palatine folds arise from

Answer 18

inner surface of maxillary facial processes

Question 19

Outer surface of median facial process become what parts of face?

Answer 19

Frontal: note vertical position of palatine folds or shelves lateral to tongue

Question 20

Outer surface of maxillary processes become what parts of face?

Answer 20

Axial

Question 21

Tongue appears in what embryonic week ?

Answer 21

4th

Question 22

Primary palate:

Answer 22

inner surface of median nasal process:

median nasal process gives rise to the nasal septum

Question 23

Palatine folds or shelves: arise from

Answer 23

medial or stomodeal surfaces of maxillary processes

Question 24

Histologic: Frontal view

Fifth embryonic week

Answer 24

The palatine folds or shelves, that arise from the inner surfaces of the
maxillary processes, are vertical in position on either side of the tongue

Question 25

The palatine folds or shelves have

Answer 25

lining epithelium that is connected to an underlying | mesenchymal tissue also called ectomesenchyme (originates in ectoderm primary germ layer)

Question 26

5th week Palatine folds move from a vertical position to a

Answer 26

horizontal position above the tongue:

Question 27

Cecum

Answer 27

blind duct

Question 28

Fifth Embryonic Week: | Frontal: palatine folds in

Answer 28

horizontal position above tongue B Looking up: position relationships of anterior of palatine folds with primary palate: The edges of these structures outline the letter ‘Y’

Question 29

Mesenchyme tissues of the palatine folds and nasal septum flow

Answer 29

toward each other:

Question 30

Structures that fuse to form the palate:

Answer 30

PP = Primary palate N = Nasal septum PF = Palatine folds Note again ‘Y’ outline at edge of structures

Question 31

Palate: Epithelial Fusion: | Begins in the

Answer 31

``` sixth embryonic week with the epithelial fusion of: primary palate (PP) with palatine folds (PF) (arms of the ‘Y’) ```

Question 32

Epithelial fusion progressing

Answer 32

posteriorly: epithelium of palatine folds fuse with each other and with epithelium of nasal septum

Question 33

A: Palatal view of:

Answer 33

``` Initial Fusion between: Primary Palate(PP) and Palatine Folds (PF) ```

Question 34

Note: most of fused epithelial cells undergo

Answer 34

cell death, some remain within the mesenchyme, as epithelial rests

Question 35

Axial views: Stages of (secondary) palate formation | Epithelial fusion and mesenchymal union occurs between

Answer 35

6 and 8 weeks IU +

Question 36

Formative stages of oral and nasal cavities: (E)

Answer 36

stomodeum no longer present

Question 37

Oral cavity view of palate

Answer 37

Epithelial fusion line and area of mesenchymal union between palatine folds and primary palate ( between 6 to 8 weeks IU+) Note that the fusion line is in the shape of a Y : Arms of Y is fusion of anterior ends of palatine folds with primary palate: Stem of Y is fusion of palatine folds with each other and above (not seen) with the nasal septum.

Question 38

Formation:

Answer 38

an organization level involved in the growth and development of an organ and an organism. (The way a particular spatial arrangement (shape) of something occurs)

Question 39

Growth:

Answer 39

increase in weight and spatial dimensions (shape) that an organ and organism undergoes

Question 40

Development:

Answer 40

the growth of an organ or organism through various formative stages on its way to maturation

Question 41

Third embryonic week: Crown- rump measurement

Answer 41

3mm (Note: In the 8th week in utero, start of fetal stage, crown-rump measurement is 30 mm)

Question 42

The stomodeum (stomatodeum) is a depression between the brain (A) and the

Answer 42

pericardium (B) in an embryo; it appears in the third embryonic week and becomes the nasal and oral cavities between 6th and 8th embryonic week. And gives rise to Rathke’s pouch ®, precursor of the anterior lobe of the pituitary gland.

Question 43

Boundaries of stomodeum

Answer 43

Superior: Frontal prominence Inferior: Cardiac plate (swelling) Posterior: Buccopharyngeal membrane

Question 44

The branchial arches and clefts, as such, appear and disappear in the

Answer 44

fourth embryonic week In this week: | Arch I becomes right and left maxillary facial processes and right and left mandibular facial processes:

Question 45

Some of the mesenchymal tissue in the branchial arches | originates in the

Answer 45

ectoderm germ layer and thus is called ectomesenchyme*

Question 46

Ectomesenchyme has similar properties to

Answer 46

mesenchyme. The major difference is that ectomesenchyme arises from neural crest cells which are a group of cells that arise from the ectoderm germ layer and form in the cranial region during early development. Ectomesenchyme plays a critical role in the formation of the hard and soft tissues of the head and neck, such as bones, muscles and tooth tissues: (dentin, cementum, pulp)

Question 47

The place where the upper maxillary and lower mandibular processes meet at either side of the stomodeum becomes the

Answer 47

commissura labiorum oris

Question 48

The 2 Mandibular facial processes replace the

Answer 48

cardiac plate as the lower boundary of the stomodeum, | the 2 Maxillary facial processes become the posteriolateral boundaries of stomodeum

Question 49

Nasal pits appear within the

Answer 49

frontal prominence: After appearance of nasal pits, the frontal prominence becomes three (3) facial processes: Median Nasal facial process and a Right and a Left Lateral Nasal facial process replacing the frontal prominence as the superior boundary of the stomodeum

Question 50

Nasal pits deepen and become

Answer 50

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

Question 51

Frontal prominence becomes 3 of the 7 facial processes:

Answer 51

Right and left lateral nasal process (2) | Median nasal proces (1)

Question 52

Paired branchial arch I beome 4 of the 7 facial processes:

Answer 52

Right and left maxillary processes (2) | Right and left mandibular processes (2)

Question 53

Median Nasal Process | Becomes:

Answer 53

* midline of nose | * philtrum of upper lip

Question 54

Lateral Nasal Processes | Become

Answer 54

* lateral sides and ala of nose | * infraorbital part of face

Question 55

Median and lateral nasal facial processes arose | from what structure that was present in the 3rd week IU?

Answer 55

Frontal prominence

Question 56

Maxillary Processes: | Become:

Answer 56

* upper part of cheeks | * lateral parts of upper lip

Question 57

Mandibular Processes: | Become:

Answer 57

* lower part of cheeks * lower lip * chin

Question 58

Maxillary and Manibular processes arose | from what basic structures?

Answer 58

Branchial arch I

Question 59

How many processes form upper lip =

Answer 59

3.

Question 60

How many processes form lower lip =

Answer 60

2.

Question 61

How many processes for cheeks =

Answer 61

4.

Question 62

7 overall processes for

Answer 62

face.

Question 63

Each Arch I becomes 4 facial processes:

Answer 63

2 maxillary, 2 mandibular | Each Cleft I becomes the external auditory meatus

Question 64

Each Arch II becomes an emrbyonic fold of tissue called:

Answer 64

o p e r c u l u m: (cover) The operculum covers Arches III and IV and Clefts II, III, IV The operculum becomes sides of neck below external auditory meatus

Question 65

Branchial cleft I becomes

Answer 65

external acoustic (auditory) meatus Each second (II) branchial arch elongates as an embryonic fold, the operculum, that overlaps clefts II and III, and arches III and IV to become the sides of the neck