face and palate development

Question 1

when does development of the face occur

Answer 1

4-8weeks in utero

Question 2

when does formation of the palate happen

Answer 2

6-10 weeks in utero

soft palate developing until around 12 weeks in utero

Question 3

when is the earliest bone laid down in the skull and where

Answer 3

6/7 weeks

in mandible

Question 4

when do more severe congenital problems generally occur during facial development

Answer 4

between 4-8 weeks

Question 5

when do more minor problems like cleft lip and palate develop during development

Answer 5

around 8-12 weeks

Question 6

what is the first pharyngeal arch also called and what does it contribute

Answer 6

the mandibular arch

Involved in contributing to structures of the face both maxillary and mandible parts of the face as well as the ear

Question 7

what are pharyngeal arches

Answer 7

= ridges or out growths of tissue

These arches are formed during the embryogenesis of all vertebrates

Question 8

how many pairs of well developed pharyngeal arches do human embryos have

Answer 8

4 pairs

Question 9

what is the problem with arch 5 in humans

Answer 9

Arch 5 either never forms in humans or if it does form it is very short lived

Question 10

what is the problem with arch 6

Answer 10

There is a question mark to whether not there is a true 6 pharyngeal arch

Question 11

what do pharyngeal arches consist of

Answer 11

consist of a mesenchymal core so the centre is made from mesoderm and neural crest cells
covered on the outside by ectoderm and separated by a series of clefts
on the inside they are covered endoderm and separated by pouches

Question 12

what are pharyngeal arches formed from

Answer 12

Formed from early embryonic tissues

Question 13

what are the structures that are found within each arch

Answer 13

Within each arch there is some striated muscle which will go on to form some of the muscles of the face
Each arch is also supplied by a major artery and has a specific cranial nerve derived from it
(important because some of the structures formed in these arches will migrate to other areas of the head and neck but they generally maintain the nerve supply that originates with them)

Question 14

what cranial nerve and muscles is the first pharyngeal arch associated with

Answer 14

trigeminal

muscles of mastication

malleus and incus

meckel’s cartilage

Question 15

what cranial nerve and muscles is the second pharyngeal arch associated with as well as bone

Answer 15

facial

muscles of facial expression

part of the hyoid bone

Question 16

what cranial nerve and muscles is the third pharyngeal arch associated with as well as major artery and bone

Answer 16

glossopharyngeal nerve

stylopharyngeus muscle

common carotid artery

parts of the hyoid bone

Question 17

what cranial nerve and muscles are the fourth (and 6th) pharyngeal arch associated with as well as other features

Answer 17

vagus nerve

muscles of pharynx and larynx

aortic arch

laryngeal cartilages

Question 18

what is the rod of cartilage within the first arch and why is it important

Answer 18

Rod of cartilage = Meckel’s cartilage

Important because the mandible forms around this cartilage

Question 19

how does the mandible form

Answer 19

intramembranous ossification
(although we have this meckel's cartilage the bone of the mandible is laid down in the mesenchyme around it)

Question 20

what else is formed from meckel’s cartilage (other than the mandible)

Answer 20

2 of the inner bones

• malleus
• incus

Question 21

what does the face develop from

Answer 21

5 prominences (or swellings) which surround a central depression - the stomodeum

Question 22

what is the stomodeum

Answer 22

the future mouth and separated from the GI tract by the oropharyngeal membrane

Question 23

name the 5 prominences

Answer 23

frontonasal
paired maxillary
paired mandibular

Question 24

what does the central frontal nasal prominence over lie

Answer 24

the developing forebrain

Question 25

what does the paired maxillary and mandibular promiences derive from

Answer 25

from the first pharyngeal arch

Question 26

what does the frontal portion of the frontal nasa promience form

Answer 26

the forehead

Question 27

at the lateral aspects of the frontal nasal prominences what can be seen

Answer 27

nasal placodes these start to grow and enlarge in the 5 th embryonic week eventually go on to form the olfactory epithelium which is involved in smell

Question 28

what is the name of the swellings around the placodes

Answer 28

nasal prominences (medial and lateral)

Question 29

what do the placodes form

Answer 29

they start to invaginate - start to depress into the tissues and form a pit the pit then goes on to form the nostrils the formation of this pit separates the nasal prominences into medial and lateral portions

Question 30

what does the little groove between the lateral nasal prominence and the maxillary prominence form in the 6th week

Answer 30

the nasolacrimal duct and lacrimal sac Start to invaginate and form a tubular structure Surrounded by bone in the adult and form a passage for draining tears from the eye into the nasal cavity As this invaginates and the lateral nasal process and maxillary process fuse they will form the alae / wings of the nose (lateral aspect of the nose surrounding the nostril)

Question 31

what happens to the medial nasal prominences in the 6th week

Answer 31

they will start to grow towards one another They grow towards the midline and fuse to form the bridge and part of the septum of the nose Also fuse with the maxillary prominences (which still grow towards the midline) to form the majority of the upper jaw The medial nasal prominence will fuse to one another to form the philtrum and tip of the nose and upper lip

Question 32

what happens to the mandibular processes

Answer 32

Fuse in the midline - where they fuse is the position of the chin Form the lower lip and jaw If they don’t fuse or only partially fuse = cleft chin or a dimple in the chin Mandibular and maxillary processes will form the cheek region (maxillary forming the majority of the upper cheeks) Where mandibular and maxillary processes fuse will form the corners of the mouth

Question 33

what happens in the development of the eye

Answer 33

Eyes start off very laterally Eye lids form around 6 weeks in embryonic development (also start to get the precursors to the ears) the eyes are open but by around week 10 the eyelids will grow rapidly together and will fuse and won't open until 7 months of foetal development

Question 34

what are the 6 little bumps in the neck region called around week 7 of development

Answer 34

auricular hillocks

Question 35

when do the ears form and how

Answer 35

The ears are starting to form their adult external form by around week 7 or week 8 still appear in neck region the ears don’t move up - the jaws instead will continue to grow and expand inferiorly so it looks like the ears are rising up towards the position of the eyes

Question 36

what does the foetus look like around week 8

Answer 36

Mandible small Stomodeum (future mouth) still taking up a large portion of the face It is recognisable, can see features but the face itself does not start to look "human" in appearance until around 4 months of development

Question 37

what adult facial feature does the frontonasal prominence make

Answer 37

forehead | bridge of nose

Question 38

what adult facial feature does the medial nasal prominence make

Answer 38

midline nose | philtrum upper lip

Question 39

what adult facial feature does the lateral nasal prominence make

Answer 39

alae of nose

Question 40

what adult facial feature does the maxillary prominence make

Answer 40

cheeks | lateral upper lip

Question 41

what adult facial feature does the mandibular prominence make

Answer 41

lower lip | jaw

Question 42

what does the medial nasal processes form

Answer 42

intermaxillary process which gives rise to the philtrum of lip and primary palate they expand inferiorly by the end of the 7th week of embryonic development

Question 43

what does the maxillary prominences give rise to in the palate

Answer 43

lateral palatal shelves | secondary palate

Question 44

what does the intermaxillary process give rise to

Answer 44

to the philtrum of the upper lip and also the primary palate which contains the 4 incisal teeth = primitive pre-maxilla

Question 45

at 6 weeks what is the realtionship between the oral and nasal cavities

Answer 45

the nasal and oral cavities are continuous so there is an open space between them These will then be separated into their individual cavities during the 7th and 8th weeks by formation of the palatal shelves

Question 46

what are the palatal shelves derived from

Answer 46

maxillary prominences

Question 47

when the palatal shelves fuse what do they form

Answer 47

secondary palate (at the back)

Question 48

what bones are within the tissues of the palate

Answer 48

maxilla and palatine

Question 49

at 9 weeks what happens to the secondary palate

Answer 49

they are starting to fuse in the midline and they will also fuse with the primary palate around the region of the incisive foramen

Question 50

what does the nasal septum form from

Answer 50

The nasal septum will form from down growths of the frontal nasal prominence and the medial nasal processes and will fuse with the surfaces of the primary and secondary palates in the midline

Question 51

what do the medial nasal processes fuse to from

Answer 51

fuse in the midline to form the inter-maxillary process = primary palate

Question 52

where does the lateral palatal shelves come from

Answer 52

maxillary process

Question 53

what can cause a facial clefr

Answer 53

Complete or partial failure of fusion between any of the swellings that develop around the primitive mouth

Question 54

what do facial clefts affect

Answer 54

feeding, speech, hearing social integration

Question 55

what are the 2 most common types of facial clefts

Answer 55

- cleft lip | - cleft palate

Question 56

where can a cleft lip extend to

Answer 56

incisive foramen

Question 57

what is a median cleft lip

Answer 57

results from the failure of the 2 medial nasal processes to fuse with each other but that is much more rare

Question 58

what do cleft lip and cleft palate defects differ in

Answer 58

differ in their distribution with respect to things like sex, familial association, population and geography it is suggested that they may have different aetiology or different causes

Question 59

what cleft lip usually result from

Answer 59

results from failure of fusion of the maxillary prominence with the medial nasal processes Can be unilateral or bilateral

Question 60

what does cleft palate result from

Answer 60

results from the failure of the 2 palatal shelves to fuse together in the midline

Question 61

is cleft lip more frequent on the left or right

Answer 61

left

Question 62

is cleft lip more prevalent in males or females

Answer 62

males

Question 63

is isolated cleft palate more frequent in males or females

Answer 63

females this is suggested to be related to their slightly later elevation of the palatal shelf as this occurs more towards week 8 (in males it tends to occur around week 7)

Question 64

what are the causes of oral-facial clefts

Answer 64

``` multi-factorial we dont know exactly these things are related • Environmental factors; ○Smoking ○ Alcohol ○ Viral infection ○ Certain drugs are thought to have an impact ○Some vitamin A analogues ``` The reason it is thought to be multifactorial is emphasised as well by the fact that in twins that cleft lip and palate in identical twins does not occur the same

Question 65

how do you diagnose a cleft lip

Answer 65

○ can be seen in ultrasound from about week 13 ○ But is usually picked up in the 20 week mid term scan ○ Certainly is identified directly following birth - within the first 72 hours

Question 66

how do you diagnose a cleft palate

Answer 66

○ Can be more difficult to see from an ultrasound

Question 67

how can cleft lip and palate be repaired

Answer 67

surgically better to be repaired early on

Question 68

what may babies with cleft lip or palate struggle to do

Answer 68

may struggle to breast feed or feed from a bottle because they can't form a seal from their mouths

Question 69

what are babies with cleft palate more vulnerable to

Answer 69

ear infections | hearing issues

Question 70

what dental issues arise from cleft lip / palate

Answer 70

teeth will potentially not develop correctly depending on location and severity of the cleft

Question 71

when are cleft lip repairs usually done

Answer 71

3-6months

Question 72

when are cleft palate repairs usually done

Answer 72

6-12 months

Question 73

what treatment may be requried alongside surgery

Answer 73

Some speech and language therapy is also required Potentially orthodontic treatment - depending on the development of the adult dentition

Question 74

throwing in a few questions from the anatomy zoom Q&A so they might not be from this practical but it is all relevant for revision and cant be bothered adding them to the correct ones x x x

Answer 74

sorry love u miss u xxxxxx

Question 75

what are suture

Answer 75

sutures are tough fibrous joints between cranial bones - with little to no movement between bones

Question 76

what are fontanelles

Answer 76

fontanelles are membranes covering the brain that haven't yet turned to bone (ossified) - they allow movement / overlapping of the bones during birth and rapid expansion of the brain and skull following birth when the bones grow together and fuse, they are replaced by sutures

Question 77

how can you tell if a symphysis is open or closed

Answer 77

if it is completely open you will be able to see the separation between the 2 bones when it is completely closed the line between the 2 joining parts will have disappeared

Question 78

when does the mandibular / mental symphysis close

Answer 78

around 1 year after birth

Question 79

how do you tell the age of someone from a radiograph if they dont develop wisdom teeth or have their wisdom teeth removed

Answer 79

if 3rd molars are not present and obvious that removed / absent then you would use alternative methods of age estimation age estimation is more accurate in younger individuals - becomes more difficult once growth and development end

Question 80

how can you tell which teeth have been lost antemortem and post mortem

Answer 80

teeth lost prior to death will display evidence of healing and the tooth socket will eventually be filled in with bone there will also be resorption of the alveolar bone in the region of the missing tooth perimortem / postmortem will be no healing and the open tooth socket will be visible

Question 81

why does bone resorb when you lose teeth

Answer 81

if you dont use bone you lose it if you lose teeth there is no mechanical stimulation so the bone starts to resorb and be removed

Question 82

what problems does alveolar bone resorption cause in relation to dentures

Answer 82

bone loss can nearly reach the mental foramen in the mandible the patient is quite close to the nerve so there can be associated pain and there is potential for it to continue to resorb right down to the mental foramen and expose the nerve

Question 83

what are sutures like in children's skulls

Answer 83

sutures are a little further apart as the bones are still growing together