Development of the skull Flashcards
all slides completed
_________: is the protective case of the brain
neurocranium
The neurocranium is derived from _____ & ____
occipital somites and somitomeres
Somites are derived from ____derm
mesoderm
The membranious portion of the neurocranium is derived from the _____
neural crest
The chondral portion of the neurocranium is derived from the______
neural crest and occipital somites and somitomere
bones of the base of the skull are formed by the _______
cartilaginous neurocranium
What is the main difference btw membraneous and cartilaginous neurocranium
membraneous: mesenchymal stage –> ossification
cartilaginous: mesenchymal –> cartilage –> bone
_____ neurocranium form the sides and roof of the skull
membranous
______: fibrous tissue membrane separating the bones of the calvaria of a newborn
fontanels
_____ are soft membranous gaps between the incompletely formed cranial bones
fontanels
_____ is the last area of the calvaria to under go ossofication.
This occurs at age: _____
anterior fontanelle
closes by 1.5 yrs
The ________ fontanelle closes at 6 months
posterior fontanelle
_____ can tell Dr. the degree of hydration of the infant
fontanel
_____ can tel a Dr. the progress of growth of the frontal and parietal bones
fontanel
_____ can tell a Dr. the level of intracranial pressure
fontanel
C.C. if an infant has severse diarrhea the _____ will be depressed
fontanel
- bc of dehydration
The anterior fontanel is the future site of the ___
bregma
union of the halves of the frontal fontanel begin by the _____ yr
second
complete fusion of the fontanel occurs by the end of the ______ yr
1st year
Name of the anterolateral frontanel
sphenoidal
- fuses with posterlateral frontanel –> less important clinically
name of Posterolateral frontanel
mastoid
The viscerocranium is mainly formed by the _________
THE FIRST TWO PHARYNGEAL ARCHES
bars of mesechymal tis
The dorsal portion of the first pharyngeal arches is called the ___
maxillary process
What three bones does the dorsal portion (maxillary process) of the first pharyngeal arches give rise to?
- maxilla
- zygomatic
- temporal
The ventral portion of the viscerocranium pharyngeal arches gives rise to the _____
meckel’s catilage (aka mandibular process)
What does the ventral portion of the first pharyngeal arch become after birth
sphenomandibular lig –> the dorsal tip of this process froms the incus and malleus
The incus and malleus is formed from the _______
sphenomandibular lig (remanents of the ventral portion of the first pharyngeal arches “meckel’s cartilage”)
The second arch cartilage of the dorsal pharyngeal arches gives rise to ____ & ____
stapes & styloid
The second arch cartilage of the ventral pharyngeal arches gives rise to ____ & ____
lesser horn & superior portion of the body of the hyoid bone
What embrylogical structure is the hyoid formed from
second pharyngeal arch (lesser horn & sup. portion)
third pharyngeal arch
At the center of the pharyngeal arches (center of the ventral and dorsal portion) is the _____
stomodeum
3 reasons that babies have small facial regions
- small size of the jaw
- virtual absence of the paranasal sinuses
- underdevelopment of facial bones at birth
The small size of a babies ____ contributes to their small facial region
jaw
The absence of a _____ in babies contributes to a small facial region
paranasal sinuses
The underdevelopment of the ____ at birth contributes to babies small faces
facial bones
The ___ of the calvaria allow for the growth of the brain (until about the age of 16)
fibrous sutures
The paranasal sinuses reach their max size during ____
puberty
- contributes to the shape of the face
___ & ___ contribute to the structure of a babies face
teeth and paranasal sinuses
Sinuses are important in altering the _____ of the face, _______ the skull, and adding ___ to the voice
shape of face
lightening of skull
resonance to the voice
c.c _____: premature closure of the sutures of the skull
craniosynostosis
cc: ____: premature closure of the sagittal suture
scaphocephaly (dolichocephaly)
cc: ___ : premature closure of coronal or lambdoid suture on ONLY one side
plagiocephaly–> lopsided head
- plagiarism of one side
cc: _____ : premature closure of the entire coronal suture
oxycephaly (turricephaly)
cc______: failure of the cranial end of the neural tube to close during 4th week of development
acrania (meroanencephaly)
____ is the absence of the calvaria & portion of the upper brain
acrania
“a”-without “crania”-head
Acrania occurs when the mother is ____ deficient
follic acid
cc________: abnormal CNS development; usually results in mentally retardation
microcephaly
_______ ossification is when the base of the skulls cartilage ossifies
endochondral ossification
c.c. metopic suture:
failure for the anterior fontanel (frontal bone) to completely fuse
c.c. caput succedaneum
when the scalp/ soft rtissure of the head schanges shape during birth and swells
mechels cartilage gives rise to the ____&____
incus & malleus
