Development of Face and Palate Flashcards
When does development of the face occur
4-8 weeks IUL
When does formation of the palate occur
6-8 weeks IUL
When is the earliest bone laid down in the skull
6-7 weeks in mandible
What forms from the first pharyngeal arch
trigeminal nerve muscles of mastication malleus incus meckel's cartilage (mandible and part of maxilla)
What is Meckel’s cartilage
mandible forms around it
ear forms from it
What are the pharyngeal arches
consist of a mesenchymal core covered on the outside by ectoderm and separated by a series of clefts and inside they are covered by endoderm and are separated by pouches
What does each pharyngeal arch contain
a central rod of a precartilaignous mesenchyme which will be tranformed into some of the adult skeletal structures
What are the 5 prominences in the face
frontonasal prominence medial nasal prominence lateral nasal prominence maxillary prominence mandibular prominence
What does the frontonasal prominence form
forehead
bridge of nose
What does the medial nasal prominence form
inter maxillary process which forms:
midline of the nose
philtrum upper lip
primary palate
What does the lateral nasal prominence form
alas of nose
What does the maxillary prominence form
cheeks; lateral upper lip
What does the mandibular prominence form
lower lip and jaw
If the mandibular processes don’t fuse what does this result in
a cleft chin or dimple in the chin (if partially fused)
Where the maxillary and mandibular processes fuse what will this result in
the corner of the mouth
What is the stomadeuom
the primitive mouth
Does the frontonasal come from the first pharyngeal arch
no
How are the nasal and oral cavities separated
they are separated into individual cavities during the 7th and 8th week by formation of the palatal shelves
What do the palatal shelves derive from
maxillary prominence
When the palatal shelves form what does this result in
the secondary palate
Where do the primary shelves fuse at
the incisive foramen
What age do we have all the deciduous dentition
2
From what age do we have a mixed dentition
6
From what age do we have all the permanent dentition
12
What can help you determine age
look at FPM look for primary dentition look for permanent dentition look for third molars look for closed/open apices
What is synchondrosis
Primary cartilaginous joint - mainly found in the developing skeleton
What is an ossification centre
Starting point for growth
What is the first ossification centre to appear
the primary ossification centre
What is a fontanelle
Membranous area (‘soft spots’) between bones of the neurocranium
What is the function of a fontanelle
Allows for compression and overlap of bones during birthing
How many fontanelles are there
1 anterior- closes around 2 years
1 posterior - closes around 1-3 months
2 mastoid (posterolateral) - closes around 6-18 months
2 sphenoid (anterolateral) - closes around 6 months
What can be seen in a fetal skull
metric suture
mental symphysis
What is the angle of the mandible in fetal skulls and females
obtuse
What is the tympanic ring
forms the ear
it is a ring rather than a plate in fetus
What does the 2nd pharyngeal arch form
facial nerve
muscles of facial expression
hyoid
What does the 3rd pharyngeal arch form
glossopharyngeal nerve
stylopharyngess
common carotid artery
hyoid
What does the 4th and 6th arch form
vagus nerve
muscles of the pharynx and larynx
aortic arch
laryngeal cartilages
What is a cleft palate due to
failure of the fusion of the palatal shelves at the midline
What is a cleft lip due to
failure of fusion of maxillary prominence and medial nasal process
