L3: Embryology of head and neck

Question 1

where does the tongue originate from ?

Answer 1

occipital myotomes

Question 2

when does the tongue begin development >?

Answer 2

around 4th week IUL

Question 3

What 3 swellings are formed by 1st pharengeal arch ?

Answer 3

tuberculum impar
2 lingual swellings

Question 4

what does the fusing of tuberculum impar and 2 lingual swellings form ?

Answer 4

mucus covering of anterior 2/3rds of the tobgue

Question 5

which brachial arch develops the hypobrchial eminence ?

Answer 5

3rd brachial arch

Question 6

what does the hypobrachial eminence give rise too?

Answer 6

mucus covering of posterior 1/3rd of tongue

Question 7

where do the muscles of the tongue originate from ?

Answer 7

occipital somites

Question 8

explain the nerve supply of the tobgue:

Answer 8

anterior 2/3rds:
sensory : lingual branch of trigeminal nerve

taste : chorda tympani branch of facial nerve

posterior 1/3rd:
sensory + taste : glossopharengeal

motor supply : all muscles are supplies by hypoglossal nerve except for palatoglossus which is supplied by the vagus nerve

Question 9

when does meckles cartilage first appear?

Answer 9

at around 6 weeks

Question 10

what kind of cartilage is meckels cartilage ?

Answer 10

hyaline

Question 11

what surrounds meckels cartilage ?

Answer 11

fibrocellular capsule

Question 12

where is the center of ossification of the mandible ?

Answer 12

at division of mental and incisive branch of inferior alveolar

Question 13

what kind of ossification is responsible for formation of mandible ( body and ramus )?

Answer 13

intramembranous ossification

Question 14

what is the point of divergence of ossification from meckles cartilage ?

Answer 14

it is marked by the lingula in adult mandible

Question 15

when is the mandible development finally complete?

Answer 15

week 10

Question 16

what is the fate of meckels cartilage ?

Answer 16

-posterior portion : incus and malleus of inner ear

-anterior portion : contributes to mandible by endochondral ossification

-sphinomandibular ligament comes from fibrocellular fibrous tissue around meckels cartilage

Question 17

what are the secondary cartilages of the mandible ?

Answer 17

condylar (most important):

-appears during 12th week
-endochondral ossification
-stays untill 2nd decade of life

coronoid :
-appears at 4 months and disapears before brith

symphysal :
-2 in number
-disappears before end of 1st year after birth

Question 18

what is the center of ossification of maxilla?

Answer 18

in maxillary process of 1st brachial arch . between antero-superior dental nerve and inferior orbital nerve

Question 19

what are the secondary cartilages of maxilla?

Answer 19

zygomatic cartilage

Question 20

which swelling comes from the forebrain?

Answer 20

frontonasal

Question 21

which mandibular arches did the maxillary and mandibular swellings come from?

Answer 21

from the 1st pharyngeal arch ( mandibular arch )

Question 22

what is the fate of all the parts of Meckel’s cartilage ?

Answer 22

posterior part : incus and malleus

fibro cellular tissue will give rise to Sphenomandibular ligament

anterior part: contribute to mandible by endochondral ossification

main part of cartilage is resorbed completely

Question 23

which brachial arch is responsible for formation of maxilla?

Answer 23

1st