Osteology Flashcards
What is the neurocranium
8 bones that encase and protect the brain
Consists of calvaria, floor, cavity
What is the viscerocranium
14 bones making up the face and skull
Develop from pharyngeal arches 1&2
What ossification does the calvatia do
Membrane to bone by intramembranous
What ossification does the floor do
Cartilage to bone by endochondral
What suture joins occipital and parietal
Lambdoid
What suture joins frontal and parietal
Coronal
Why can you not see sutures on inside of old persons skull
Disappear from inside out
What are the fontanelles and when do they fuse
Unossified membranous gaps between flat bones
Anterior - 18 months - 2 years
Posterior- 1 - 3 months
What is early fusion of fontanelles called
Craniosynostosis
What are the fontanelles called in adults
Bredma and lambda
Why are fontanelles important
Allow shape of head to change during birth and as brain grows
What does bulging fontanelle indicate
Raised ICP
What does sunken fontanelle indicate
Dehydration
What are some features of calvaria bone
Inner spongy (diploe) bone between compact bone
Tri laminar
Protective strength without extra weight
What does the ACF contain
Cribriform plate- CN1 enters
What does the MCF contain
Petrous part of temporal bone
Optic canal
SOF
Why is petrous part of temporal bone important
Hardest bone
Houses middle and inner ear structures
Features of linear skull fracture
No bone displaced, straight
Features of comminuted skull fracture
Multiple fracture lines
Depressed or non-depressed
What is the pterion and significance
Thinnest area of skull
Middle meningeal artery lies under = extradural haemorrhage
If CSF from nose what does it mean
Ethmoid bone fracture
ACF fracture
If CSF from ear what does it mean
MCF fracture involving petrous bone
What does periorbital ecchymosis indicate
ACF fracture- blood pools
What does battles sign indicate
MCF fracture
Features of the TMJ
Two synovial cavities divided by fibrocartilaginous disc
Innervated by auriculotemporal nerve- sensory (Vc)
Stabilised by capsule and extracapsular ligaments
How does the TMJ move
Hinge (inferior half) and gliding forward (Superior half)
Retraction and protraction of mandible
Which muscles help open mouth
Lateral pterygoid- held glide forward
What muscles help close mouth
Masseter
Temporalis
Medial pterygoid
What muscles retract mouth
Posterior fibres of temporalis
What muscles protrude mouth
Lateral pterygoid
Medial pterygoid
How does the TMJ dislocate
Trauma
Yawning
Locks in open due to anterior dislocation of condyle over articular tubule
What keeps a dislocated jaw locked open
Contraction of mastication muscles around joint keep it anteriorly displaced
