ex1.formation of face and oral cavity

Question 1

what is the stomodeum?

Answer 1

the stomodeum is a space that eventually brecomes the oral and nasal cavities. the stomodeum is bordered by the frontal prominence, the buccopharyngeal membrane, and the cardiac plate.

Question 2

during what weeks of embryonic development does the stomodeum appear?

Answer 2

the stomodeum appears during the 3rd week of embryonic develpment. he stomodeum develops into the oral and nasal cavities between weeks 6-8 of embryonic develpment

Question 3

what happens to the stomodeum in weeks 6-8 of embryonic development?

Answer 3

the stomodeum becomes the oral and nasal cavities in the 6-8h week of embryonic development – the formation of the hard and soft palate are needed to divide the space into the 2 cavities.

Question 4

what occurs in week 4 of development of the embryo (regarding the face..)

Answer 4

in week 4, there are 4 paired BRANCHIAL ARCHES and brancial CLEFTS/grooves.

the branchail archesa and cleafts both appear and DISAPPEAR in week 4 of embryonic development

Question 5

where is the stomodeum located in regards to the branchial arches/clefts during week 4 of the embryonic devlopment?

Answer 5

the stomodeum is located within/bt 2 portions of branchila arch 1. Arch one has a dividing cleft (the stomodeum) that divides the arch into the maxillary (supr) and mandibular (inf) processes.

Question 6

in the 4th week of embryonic development - what does branchial arch 1 become?

Answer 6

in the 4th week of development, branchial arch 1 becomes the rt/left MAXillary facial processes (supr to the stomodeum) and the rt/left MAND facial processes (inf to stomodeum)

Question 7

where is branchial cleft 1 located and what does it form?

Answer 7

branchial cleft 1 is located inferior to branchial arch 1. // branchail cleft 1 will eventually form the external auditory meatus.

Question 8

at the end of the stomodeum (like a cleft), the ends of the MAND and MAXillary facial processes meet – what is this location called? what does it become?

Answer 8

where the maxillary and mandiubular facial proceses meet is called the commissura labiorum oris. This structure is what we know as the commisure, located at the corner of the mouth (where the upper and lower lips meet)

Question 9

In the 4th week of the embryo, what becomes the new boundaries of the stomodeum (the eventual oral/nasal cavity space)

Answer 9

in the 4th week, the 2 mandibular facial processes replace the cardiac plate as the lower stomodeum boundary .

the 2 maxillary facial processes (from branchail arch 1) form the posteriolateral boundaries of the stomodeum.

Question 10

in what week do the nasal pits form?

Answer 10

the nasal pits form in the 4th week of embryonic develpment

Question 11

where do the nasal pits develop in the 4th week?

Answer 11

the nasal pits develop in the frontal prominence (supr border of stomodeum )

Question 12

after the nasal pits appear in the 4th week, how is the frontal prominence divided?

Answer 12

after the appearance of the nasal pits, the frontal prominence becomes 3 processes: the

• median nasal process
• right / left nasal facial processes .. these processes replace the frontal prominence as the supr boundary of the stomodeum

Question 13

How many facial processes form the face?

Answer 13

there are 7 processes (7 developmental areas) that form the face

Question 14

What 2 strucutures form/become the 7 facial processes?

Answer 14

recall:
- branchial arch 1 forms the rt/left maxillary and mandibular processes (4 tot facial processes)
-the frontal prominence becomes the median nasal prominence and the rt/left lateral nasal processes
= a total of the 7 facial processes that form the face

Question 15

what does the median nasal process become?

Answer 15

the median nasal process becomes the
-midline of the nose, and the philtrum of the upper lip

• the median nasal process developed FROM the frontal prominence (recall, the frontal prominence was hte area that formed the supr boundary to the stomodeum)

(philtrum = the little divot above the lip under the nose at the midline of the face)

Question 16

what do the lateral nasal processes become ? (rt/left)

Answer 16

the lateral nasal processes become the
-lateral sides and ala of hte nose, and the infraorbital part of face

the rt/lft lateral nasal processes orignated from the frontal prominence (recall, the frontal prominence = the supr border of the stomodeum.. the processes form in the 4th week)
(ala = the cartilages of the nostrils)

Question 17

In what week of embryonic development do the 7 facial processes develop?

Answer 17

the 7 facial processes develop in the 4th week of ebryo development. 3 of the processes come from the frontla prominence (medan and 2x lateral nasal prceses) and 4 facial processes come from branchail arch 1 (rt and left max and mand facial pricesses)

Question 18

the median and latera nasal facial processes arose from what strucutre that was present in the 3rd week in utero?

Answer 18

the median and lateral nasal processes arose from the frontal process ((supr to the stomodeum) which was present in week 3 of development in utuero

(melfi question)

Question 19

what do the 2 maxillary processes become?

Answer 19

the right and left maxillary processes become the
-upper parts of the cheeks, and lateral parts of the upper lip

( the maxillary process developed from the supr portion of branchail arch 1 in week 4 of in utero)

Question 20

what do the 2 mandibular processes become?

Answer 20

the right/ left mandibular processes become the
-lower part of the cheeks, lower lip, and chin

(( the mandibular process developed from the inf portion of brnachial arch 1 in week 4 of in utero)

Question 21

maxillary and madibular processes arose from what basic strucutres?

Answer 21

the max and mand proceses arose from branchial arch 1 (brnach arch 1 appeared in week 4 and the processes developed from it is week 4. very quick.)

– melfi question

Question 22

during development in the 4th week, the rt/left lateral nasal processes merge with the median nasal process ((all from the frontal prominence) … what happens if this merge is unsuccessful?

Answer 22

If hte merger bt the lateral nasal processes and the median nasal process is unsuccessful, then the result is a CLEFT – think.. the 2 processes merge along the ala of the nostrils (opening cartilage) and lateral sides of the bridge of nose))

Question 23

what happens if the maxillary and mandibular processes do not merge? is this a common occurrence?

Answer 23

if the mandibular and maillary processes do not form, then the commissurra labiorum oris will not form and the area will be a cleft.

This is an UNCOMMON occurrence

Question 24

In the developing embryo supr to inf as of the 4th week , there is branchial Arch 1 containing the stomodeum, then branchail cleft(aka groove) 1, then branchial arch 2, b. cleft 2, .. etc to branchial cleft 4.

what does (rt/left) Arch 2 become?

Answer 24

branchial arch 2 becomes the operculum (seen as 2 folds emerging from b. arch2 and developing inferiorally to the inf end of cleft 4))

the operculum = covering and covers arches and clefts 2-4.

eventually, the operculum bceones the sides of the neck below the external auditory meatus (b. cleft 1)

Question 25

.. clinically, if the operculum persists, how does it look? and could a cyst develop?

Answer 25

The operculum, a tissue fold from b. arch 2, may persist. If so, it looks like a bump/bulge on the lateral side of the neck .

Yes, if the operculum persists, its location could form a cyst = a branchial arch cleft cyst.

Question 26

what is a cyst?

Answer 26

A cyst is a sac-like pocket of tissue that contains fluid, air, or other substances. Cysts can grow almost anywhere in your body or on your skin.// they feel like large peas under the skin

Question 27

In the 5th week of development, the MAX illary faical processes and the median nasal processes are supposed to merge .. what happens if they do not?

Answer 27

if the maxillary facial proceses and the medial nasal process do not merge, a CLEFT LIP will resutl (think: the median nasal process covers the area of the central birdge of nose to the philtrum + middle upper lip, the maxillary processes cover the rest of the upper lips and upper cheeks)

Question 28

at what point in humans is an embryo become a fetus?

Answer 28

In humans, the embryo becomes a fetus at 8 weeks old

Question 29

what happens to the buccopharygneal membrane (recall, the middle boundary of the stomodeum) in week 4?

Answer 29

in week 4, the buccophrygeal membrane ruptures allowing a communication bt the stomodeum and the foregut. the opening formed will become the nasal and oral pharynx (throat)

Question 30

In what week do the lingual swellings that form the tongue develop?

Answer 30

The lingual sweelings that eventually form the tongue appear in week 4.

Question 31

what branchial arches/clefts contribute to the development of the tongue?

Answer 31

Branchial arches 1,2, 3 form lingual sweelings along the vetral side of the foregut tube near the stomodeum.

Question 32

how many lingual swellings are there that merge to make up the tongue?

Answer 32

4 lingual swellings- 2 lateral lingual + 2 tuberculum impar of the b. arch 1 AND the (large) copula swelling from b. arches 2,3

Question 33

which lingual swellings form which parts of the tongue?

Answer 33

there are 4 lingual swellings. the 3 contributed by branchail arch 1 are the tuberculum impar flanked by the 2 lateral lingual swellings. These 3 swellings merge to form the ANTERIOR 2/3 of the tongue

the 4th large lingual swelling is the copula that is from branchial arches 2,3. This forms the posterior 1/3 and root of the tongue.

Question 34

in what cavity is the tongue located?

Answer 34

the tongue is located in the stomodeum.

Question 35

when and where from do the oral and nasal cavities form?

Answer 35

The oral and nasal cavities form in the 6th week of embryonic development. These form from the stomodeum.. the stomodeum will be partitioned into the oral and nasal cavities

Question 36

when do the primary palate, the nasal septu,m, and palatine folds/shelves appear? what structure do they contribute to?

Answer 36

the primary palate, the nasal septum, and palatine folds appear in the 6th week of hte embryo.
these parts form the palate.

Question 37

what processes have parts that contribute to the final palate?

Answer 37

the median nasal process and the maxiilary facial processes contribute to the palate.

• the median nasal process (inner surface) forms the primary palate> which forms the nasal septum
• the MAX facial process (inner surface) forms the palatine folds

the primary palate, nasal septum, and both palatine folds all fuse to form the palate

Question 38

did the nasal septum come from the frontal prominence or the brnachial arch 1 or brnachail cleft 2?

Answer 38

the nasal septum < primary palate < median nasal process < frontal prominence.

• brnachial arch 1 = the MAx and mand (4 total) faical processes
• brnachial cleft 2 = forms the operculum (tissue cover of celft 2-cleft4)

Question 39

The palatine folds (of the MAX facial processes) have lining epithelium and an underlying mesenchyme … is the mesenchyme endo- or ectomesenchyme?

Answer 39

There is ECTOmesenchyme underlying the lining epithelium of hte palatine folds. the ectomesenchyme originates in ectoderm primary germlayer

Question 40

How do the palatine folds change position in relation to the tongue in the 5th week?

Answer 40

In the 5th week, the palatine folds change position from being vertically oriented inferiorally-reaching to the tongue (the folds = caudal to the tongue) and the move superiorally to lie in a horizontal roof-like plane superior to the tongue.

the tongue also drops a bit (not sitting as tall on its root)

Question 41

True/ False. In week 5, the palatine folds form a horizontal plane supr to the tongue, and merging of the clefts bt the brnachial arches occurs.

Answer 41

True. In week 5, the palatine folds form an incomplete (not yet merged) roof above the tongue. the branchail clefts are merging .. incomplete merging here (and throgh weeks 8) will result in a cleft.

Question 42

T/F If looking at the roof of the mouth, the merging processes form a “Y” shape that invovles the primary palate and the two palatine folds

Answer 42

True. The primary palate is bt the arms of the Y and surrounded by the 2 palatine folds.

-The primary palate is from the median nasal process (of the frontal prominence) while the palatine folds are from the rt/left MAX processes (of brnchial arch 1)

Question 43

when do the lining epithelia of the primary palate and the palatine folds merge?

Answer 43

the lining epithelia of the primary plate and the palatine folds (the “Y” arms, aka, anterior of the forming mouth/palate) fuse in the 6th week of embryo.

Question 44

in what progression does the palate form?

Answer 44

the palate starts to form in week 6- (the parts of the palate: the primary palate, nasal septum, and palatine folds– all developed in week 5) – first the primary palate and palatine folds fuses (the “Y” arms”) then the palatine folds fuse from anterior to posterior along the midline with the nasal septum to form the hard palate, and the palatine folds fuse with each other most posteriorally to form the soft palate

Question 45

As the palatine folds, etc fuse.. what may develop if the lining epithelium does not completely disappear?

Answer 45

during fusion of hte palatine folds, etc (– basically, any area of merging) if the lining epithelia persists, a CYST may form

Question 46

what happens to the lining epithelia as the palatine folds merge?

Answer 46

the lining epithelia of the merging palatine folds ought to break-down and disappear. the mesencyhes of the different parts should meet up. = a MESENCHYMAL UNION. otherwise.. lining epithelia is a barrier.. can possibly form a cyst.

** a mesencymal union also occurs bt the primary palate and the palatine folds (recall, mesencymal union = the merging of diff parts that are confined by lining epithelia, the epithelia breaks down allowing the mesencyme of the 2 parts tpo merge together and not be distinct.

Question 47

what development marks the formation of the secondary palate?

Answer 47

the merging of the primary palate and the palatine folds + nasal septum along the seems, along witht he breakdown of the lining epithelia and subsequent MESENCYMAL UNION .. the palate is deemed the secondary palate. The secondary palate divides the oral from nasal cavities

Question 48

the oral and nasal cavities are divided by what struvture?

Answer 48

the secondary palate divides the stomodeun into the oral and nasal cavities.

Question 49

what parts contribute to the hard palate? and which to the soft palate?

Answer 49

The hard palate is formed anteriorally by the mesencymal union of the primary palate ( fromt he median nasal process < frontal prominence) and the palatine folds (max process/ branch arch 1) .. then the palatine folds merge togerther + and with the nasal septum (from primary palate) to form the hard palate. Most dorsally, the 2 rt/lft palatine folds merge together to form the soft palate

Question 50

In what weeks IU does epthelia fusion and mesenchymal union of palatal struvutres occur ?

Answer 50

between weeks 6-8 is the epithelial lining fusion + mesenchymal union of the palatal structures

Question 51

Are there any hard tissues present throgh week 8 as the primary palate is formed?

Answer 51

No. Through week 8 all of these fusions and struvutres are all soft tissues. No bone. Bone will eventually form in the mesenchyme (mesencymal union occurred!)