development of the face

Question 1

what day does neural plate formation occur at

Answer 1

day 17 -

Question 2

what day does the formation of the neural folds, neural groove occur on

Answer 2

day 18

Question 3

why does spina bifida happen?

Answer 3

because the posterior neuropore of the neural tube doesn’t close. why it doesnt close is becaause of a lack of folate. folate is KEY in the closing of the ant and post neural tube
folate: folic acid (vit B9)

Question 4

when do the neuroporesclose (which order)

Answer 4

ant neuropore closes at day 24
post neuropore closes at day 26

Question 5

what are the basic steps of neuralation

Answer 5

1. ectodermal proliferation
2. neural plate formation due to the formation of the neural folds and grooves
3. neural crest cell formation at edges of neural folds
4. neural tube formation
5. closing of the ant and post neuropores

Question 6

how does the neural tube form?

Answer 6

edges of the neural folds fuse with one another, neural grove moves down (invaaginates) so now this tube becomes underneath the ectoderm and within the mesoderm.
neural crest cells sit on top of the neural tube underneath the ectoderm

Question 7

what end of the neural tube is the anterior neuropore at?

Answer 7

cranail end

Question 8

what end of the neural tube is the posterior neuropore at?

Answer 8

caudal end

Question 9

where is the notochord developed from?

Answer 9

mesoderm cells form it after gastrulation is complete

Question 10

what membrane forms the oral cavity

Answer 10

buccopharangeal membrane

Question 11

what does the ectoderm form in the pharyngeal apparatus

Answer 11

pharyngeal clefts

Question 12

what does the mesoderm form in the pharyngeal apparatus?

Answer 12

pharyngeal arches

Question 13

what does the endoderm form in the pharangeal apparatus

Answer 13

pharangeal pouches

Question 14

what is the stomodeum

Answer 14

gap between developing face of the embryo and the first pharyngeal arch

Question 15

where is the buccophaarangeal membrane located

Answer 15

within the stomedeum

Question 16

when and how does the developing embryo fold?

Answer 16

the embryo will start folding so that the caudal and cranial end almost meet at 4 weeks

Question 17

what structures are in each pharangeal arch?

Answer 17

artery
cartilage
nerve

Question 18

which nerves innervate every pharangeal arch

Answer 18

PA1 = TRIGEMINAL
PA2 = FACIAL
PA3 = GLOSSOPHARANGEAAL
PA4 = VAGUS
PA6 = RECCURANT LARANGEAL NERVE

Question 19

how does the ectomesenchyme form

Answer 19

neural crest cells migrate to the mesoderm forming the ectomesenchyme ->which is an important connective tissue for different structures

Question 20

function of the ectomesenchyme?

Answer 20

form of mesenchyme , consisting of neural crest cells -> this forms the tissues of the head and neck including: bone, cartilage, connective tissue and dentine

Question 21

what does the first pharyngeal arch form

Answer 21

mandible
maxilla

Question 22

what tissues of the tooth do ectomesenchyme cells make

Answer 22

all tissues except enamel

Question 23

what pharyngeal arch is affected by failure of neural crest cell migration

Answer 23

First arch syndromes are congenital defects caused by a failure of neural crest cells to migrate into the first pharyngeal arch. They can produce facial anomalies. Examples of first arch syndromes include Treacher Collins syndrome and Pierre Robin syndrome.

Question 24

what is treacher collins syndrome and what is it caused by

Answer 24

• autosomal dominant condition
• caused by a mutation in the TCOF1 gene
• this gene is required to make a protein (treacle) that plays a critical role in formation of bone and tissues of the face

Question 25

what are the characteristics of treacher collins syndrome?

Answer 25

Is characterised by downward-slanting eyes, micrognathia, absent or malformed ears and clefts of the lips and palate

Question 26

what is micronathia?

Answer 26

abnormality when the mandible is reduced in size

Question 27

what week would first arch syndromes occur

Answer 27

during week 4 of intrauterine life

Question 28

what is Pierre Robins sequence and what does it result in babies

Answer 28

recessive condition
causes micrognathia, glossoptosis - displacement of the tongue which causes respiritory distress and difficulty feeding due to velopharangeal insuffieicenty and clefts of the lip and palate

Question 29

facial features of FAS

Answer 29

fetal alcohol spectrum disorder:
- small eye openings
-smooth philtrum
-small upper lip

Question 30

what week does the tongue develop?

Answer 30

week 4 of intrauterine life

Question 31

what develops the mucosa of the anterior 2/3rds of the tongue?

Answer 31

lateral lingual swellings and tubercular Impar
BOTH FROM 1ST PHARANGEAL ARCH

Question 32

what develops the mucosa of the posterior 1/3 of the tongue

Answer 32

copula
from the 2nd, 3rd and 4th pharyngeal arch

Question 33

what develops the epiglottis and from which pharyngeal arch

Answer 33

epiglottic swelling from the 4th pharyngeal arch

Question 34

name the lingual and 3 medial swellings of the tongue

Answer 34

> lateral lingual swelling
tubercular impar
copula
epiglottic swelling

Question 35

what forms the muscles of the tongue

Answer 35

The intrinsic and extrinsic muscles of the tongue are derived from occipital somites, which are segments of mesoderm in the region of the upper neck.

The somites migrate from the neck anteriorly to give rise to the muscles of the tongue.

Question 36

how are somites formed? what are somatocoels?

Answer 36

mesoderm -> from paraxial mesoderm, these form cavity and split into sections -> which are called somites
somatoceols are cavities within the somites

Question 37

how do somites further differentiate?

Answer 37

the somatocoels split into sections:
1.dermatomyotome
2. scleratone

the dermatomyotome further differentiates into:
1. dermatome
2. myotome
3. sclerotome