sievert cranial cavity Flashcards
two divisions of the skull
neurocranium (bones around brain)
viscerocranium (facebones)
neurocranium formation
large flatbones, most formed INTRAmembranously…
PARAXIAL MESODERM (somites)
laryngeal bones come from what embryo origin?
lateral plate mesoderm
prechordal plate
The division between neural crest derived and paraxial derived occurs at the ROSTRAL end of the notochord
why do you tend to see heart tube defects accompanied w/ skull defects?
the mesenchyme that is neural crest in origin that makes the face is form the same block that makes the heart!!!!
embryo derivative of the viscerocranium?
neural crest and ectoderm
sphenoid bone embryo
everything anterior to the body =ectoderm and neural crest
everything posterior to that = paraxial mesoderm
most of the bone develops by what kinda bone formation?
membranous!
what parts of the neurocranium are referred to the as the chondrochranium coz they do endochondrial ossification?
most of sphenoid, the ethmoid, and part of the temporal and occipital bones
viscerocranium bone dev
- membranous
- neural crest
cartilagenous exceptions: middle ear ossicles, laryngeal cartilages, and hyoid bone
why are craniofacial defects so common?
coz lots of the skull comes form neural crest
why is newborn face so small?
small jaw, no teeth, and no paranasal sinuses… and underdeveloped facial bones
craniostynosis vs cranioschisis
stynosis = premature suture closure schisis= incomplete closure of neural pore (amniotic fluid eats up brain tissue and relts in anencephaly)
cranioschisis results in
ancephaly
additionally can also get: cranial meningoencephalocele (meninges bulging out w/ brain tissue out too) and cranial meningocele (just meninges bulging out)
is there an epidural space in c-cavity?
nope! coz dura is tightly fused to cranial bones
meningeal arteries location
maxillary artery —> middle meningeal traveling through foramen spinosum —-> travel between dura and cranium
note they are not embedded within the dura… though they erode the skull bone and the dura
what forms the periosteum of the int. cranial cavity?
dura mater
two layers of the dura
periosteal and meningeal, but they’re fused together all the way down to the foramen magnum
exception: dural sinus and dural reflections
why is one meningeal artery more important?
middle meningeal is most important coz the anteiror and posterior meningeal arteries go to areas where bone is really thick
epidural hematoma etiology and include hallmark
etio: forms between dura and the bone.. a high pressure bleed can disect the dura from the bone, causing an artificial space where the blood can chill and create pressure in
- increase in pressure will mess up respiratory and cardiovascular centers down by the foramen magnum
- hallmark: lucid interval
arachnoid appearance
and subarachnoid vessel basics
lightish, clearish membrane that has CSF underneath it.
there are vessels (veins) in the subarachnoid… they can pierce the arachnoid, and then pierce the dura to enter dural sinuses
location of pia on brain?
directly on surface of all sucli and gyra
why are high speed changes bad for the brain?
you can shear off the veins that enter the dural sinuses from the subarachnoid space, causing a SUBDURAL hematoma
fxn of arachnoid granulaitons
- they’re modified from arachnoid…
- fxn: one way valvs that pierce into dural venous sinuses and allow CSF to percolate in, giving the brain buoyancy and adding nutrients and stuff
emissary vein pathological fxn
connects scalpt to dural venous sinus
patho: infection form outside can come into the dural sinus… especially bad coz the loose areolar tissue is prone to infections
two types of subdural hematomas
acute (traumatic brain injury, rapid blood flow, poor outcome, surgery a must)
chronic (long and low, usually observation and drainage will cure, and good outcomes)
the big dural reflexions to know fasho
falx cerebri
tentorium cerebelli
falx cerebelli
