OS III, Ex II, skull, pharyngeal arches and face Flashcards
To main parts of skull
neurocranium- holds brain, and visocranium - face and anterior neck.
How are the cartilagious parts of skull formed?
enchondrol ossification
How aer the membranous bones of skull formed
intramembranous ossification
What parts of neurocranium are cartilaginous?
chondrocranium, the cranial base bones
What parts of viserocranium are cartilaginous?
ossicles, hyoid bone
What parts of viserocranium are membranous?
face bones
what three factors help derive skull bones and cartilage
1) outer epithelial layers, 2) mesodermal somites, 3) neural crest cells migrating from neural tube area
what guides the eventual shape of skull?
the soft tissues of the brain, CT and muscle around it.
What are the membranous parts of the neurocranium
Vault bones (ones over top) and fotanells that span bones
how is the cranial base formed?
cartilage islands fuse , ethmoid, sphenoid, petrous temporal, occipital bones are turned to bone via enchondrial ossification
What type of joints between the bones of the cranial base?
synchondrosis types so that they can grow longer and laterally
when does the spheno ethmoid and spheno- occipital joints close
in mid teens,
What happens in the mid teens?
spheno - ethmoid and spheno occipital joints close making longtudinal growth no longer possible
What bones determine the width of the skull?
temporal and sphenoid bones with their lateral growth.
what forms the cranial base angle between occipital and sphenoid bones
Remodeling of sphenoid bone that alignes with cephalic ancle of neural tube.
What predicts mandible position and susceptibality to malocclusions
cranial base angle between occipital and sphenoid bones
Large angel causes what?
under bite
Small angel causes what?
under bite, angle pushes jaw more forward
Large angle btween Spheno-icc is associated with wat
square jaw ans overbite
Small angle is associated with what?
wide angled mandibles, underbite
What creates pharyngeal arches?
condensation of mesenchyme and neural crest cells
What are the pharyngeal arches associated with?
Cranial nerves, cartilage, and or artery, aortic arch
What gives rise to many structures of the anterior neck and face? (visocranium)
pharyngeal arches
in the pharyngeal arches, what happen to the cartilage?
most of its replaced via intramembranous ossification
What cartilage is replaced via enchondrial ossification?
hyoid and styloid process, the rest of the face is intramembanous ossificaiton
Neural crest cells migrates and interacts with what in pharyngeal arche
Neural crest cells interact with mesenchyme
What does the neural crest cells and mesenchyme form?
bones, cartilage, skin, arteries and nerves of the face.
Where do the pharangeal arches develop, the viso or neuro cranium?
the visocranium is where the pharnygeal arches develop
What arches are we concerned with?
Mandibular arch, Hyoid arch, 3rd, 4th and 6th.
Mandibular arche does what?
Trigenimal nerve, then the bones of the face, ears, and muscles to work chewing and hearing
Hyoind arch does what?
Facial nerve, hyoid, stapes styloid proces, and muscles for swallowing and facial expression
3rd arch is for what?
glossopharyngeal, hyoid and stylopharyngeus
4th and 6th arch?
vagus nerve, larynx, and muscles of pharynx laryns
Groove 1, on the outside is for what?
external acoustic meatus
What are the internal 4 pouches for?
Tympanic cavity autidory tube (ear), Palatine tonsil, thymus parathyroid migration, parathyroid and C cell migration
How does thyroid gland get to where its going?
descents through tongue, through foramen cecum, thyroglossal duct anterior to hyoid bone and lands below larynx
What can go wrong during the thyroids descent?
ectopic thyroid tissue that get stuck along thyroglossal duct
what is a pyramidal lobe?
thyroid tissue that didn’t quite reach target area, looks like a horn in the middle of thyroid pointing up throat
what lobe does face development?
all the arches expand and fuse to form the bones, muscles, and ct of Face
How is face formed by the 1st parangeal arche?
medial migraion and fusion of maxillary, mandibular, nasomedial and nasolateral processes.
what is the cause of a cleft lip?
Maxillary and medial nasal rominences that fail to fuse properly
what causes cleft palate?
failure in fusion of palatine process
what fuse to make palate?
palatine processes of maxilla the fuse with septum
signs of fetal alcohol syndrome?
smooth philtrum, thin upper lip and wide set eyes
what causes facial signes of fetal alcohol syndrome?
incorrect closure of maxillary and nasal prominances
Other problems with FAS?
stunted physical and emotional development, trouble with time, reality, impulse control, remorse. Cause and effect.
