L3: Embryology of head and neck Flashcards
where does the tongue originate from ?
occipital myotomes
when does the tongue begin development >?
around 4th week IUL
What 3 swellings are formed by 1st pharengeal arch ?
tuberculum impar
2 lingual swellings
what does the fusing of tuberculum impar and 2 lingual swellings form ?
mucus covering of anterior 2/3rds of the tobgue
which brachial arch develops the hypobrchial eminence ?
3rd brachial arch
what does the hypobrachial eminence give rise too?
mucus covering of posterior 1/3rd of tongue
where do the muscles of the tongue originate from ?
occipital somites
explain the nerve supply of the tobgue:
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
when does meckles cartilage first appear?
at around 6 weeks
what kind of cartilage is meckels cartilage ?
hyaline
what surrounds meckels cartilage ?
fibrocellular capsule
where is the center of ossification of the mandible ?
at division of mental and incisive branch of inferior alveolar
what kind of ossification is responsible for formation of mandible ( body and ramus )?
intramembranous ossification
what is the point of divergence of ossification from meckles cartilage ?
it is marked by the lingula in adult mandible
when is the mandible development finally complete?
week 10
what is the fate of meckels cartilage ?
-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
what are the secondary cartilages of the mandible ?
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
what is the center of ossification of maxilla?
in maxillary process of 1st brachial arch . between antero-superior dental nerve and inferior orbital nerve
what are the secondary cartilages of maxilla?
zygomatic cartilage
which swelling comes from the forebrain?
frontonasal
which mandibular arches did the maxillary and mandibular swellings come from?
from the 1st pharyngeal arch ( mandibular arch )
what is the fate of all the parts of Meckel’s cartilage ?
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
which brachial arch is responsible for formation of maxilla?
1st
