S2 osteology Flashcards
2 parts of skull
neurocranium (envelops/protects brain):
- calvaria (skull cap/vault)
- cranial floor
- cranial cavity
viscero cranium - facial skeleton and jaw:
neurocranium- how do these bones begin?
calvaria- as membranes (intramembranous ossification)
floor - as cartilage (endochondrial ossification)
flat bones of calvaria
frontal parietal greater wing of sphenoid bone temporal occipital
joints of calvaria
coronal suture- between frontal and parietal
bregma - where coronal suture and sagittal meet
saggital- between two paired parietal
lambdoid- between occipital and parietal
lambda- (previous fontanelle). meeting of saggital and lambdoid
what is fontanelle? function? fuse when?
infant skull
area of unossified membranous gaps between bones of calvaria
> allows for alteration of skull size and shape during birth
permit growth of brain
fuse
anterior - 2yrs
posterior - 1 to 3 months
what is craniosynostosis?
early fusion of fontanelles and sutures (rare condition) require survival intervention to break joint. and allow movement of skull bones
clinical relevance of anterior fontanelle?
convex shape- healthy baby
gentle palpation to assess intracranial pressure and state of hydration
- bulges under high pressure
- depresses when dehydrated
take in context with how baby appears
what is the arrangement of calvaria bones in cross section?
trilaminar arrangement
- compact bone= outer table
- spongy bone= diploe
- compact bone=inner table
> offers protective strength without adding significant weight
-periosteum covers outer and inner table
what depressions form the cranial floor?
anterior, middle and posterior cranial fossae (bowl shaped depressions)
where is ethmoid bone found?
anterior cranial floor
nose part
which bones form cranial floor?
- ethmoid bone
- sphenoid bone ( 2wings)
- temporal bone
- occipital bone
what bone houses middle and inner ear structures?
petrous (very hard bone) part of temporal bone
difference between linear and comminuted skull fractures?
linear- fairy straight, no bone displacement
comminuted-multiple fracture lines. fragments may displace inwards(depressed)
what is the thinnest area of skull? its underlying vessel?
pterion- meeting of 4 bones
underlying blood vessel= middle meningeal artery
what is a basilar fracture? signs and symptoms?
skull base fracture -rarer
SS:
fluid dripping from nose after hard injury (CSF)- ethmoid fracture
periorbital ecchymosis- bruising around eyes > fracture. of orbital plates of anterior cranial fossa
battle sign- bruising around mastoid process- involving petrous bone
blood and CSF leaking from ear- middle cranial fossa involving petrous bone
haemotympanum-blood pooling in middle ear cavity
