Anatomy- Cranial meninges, and cranial contents Flashcards
What surrounds the brain?
the neurocranium
what are the bones of the face called collectively?
the viscerocranium
What bones of the face come from neural crest, ectoderm?
frontal, nasal, sphenoid, lacrimal, zygomatic, maxilla, incisive, mandible, sq. temporalis, hyoid
What bones of the face come from paraxial mesoderm (somites)?
parietal, pet temporal, occipitals,
What bones are made up of lateral plate mesoderm?
laryngeals
The division between neural crest derives bone and paraxial mesoderm derived bone occurs at the rostral end of the notochord at the (blank)
prechordal plate
The neural crest cells that make up the some of the bones of the skull are also the same neural crest cells that make what?
Heart and heart tube (hence why you sometimes get Craniofacial defects along with CV defects)
Is there paraxial mesoderm in front of the prechordal plate?
no, only neural crest cells
How can the neurocranium be divided?
into a membranous and cartilaginous part
What does the membranous part of the neurocranium consist of?
most of the flat bones that surround the brain (frontal, parietal, parts of temporal and occipital)
the name membranous comes from their method of ossification i.e intramembranous**
the neurocranium develops primarily as (blank) bone
intramembranous
What does the cartilaginous neurocranium consist of?
How do these bones develop?
sphenoid bone, ethmoid bone, part of tempoal bone and part of occipital bone
endochondral bone ossification
Bones of the cranium arise from one source or multiple sources?
multiple sources
What are the exceptions to the rule that all large flat bones of the neurocranium are membranous?
part of occipital bone, part of temporal bone
(blank) develops primarily from membrane and comes from neural crest
viscerocranium
Some parts of the viscerocranium develop from cartilaginous models…. what three bones are these?
middle ear ossicles, laryngeal cartilages and hyoid bone
Why do newborns have such small faces?
they lack teeth which results in small jaw, they have no paranasal sinuses and facial bones are underdeveloped
What are fontanelles?
6 areas where flat bones of skull meet and along with the sutrues, allow for overlap during the birthing process
Premature suture closure results in (blank)
craniosynostosis
Incomplete closure of the anterior neuropore cause the skull bones to fail to grow together and can result in (blank).
crainioschisis
Why is it bad if you have premature suture closure as an infant?
because you limit further brain development
Please explain cranioschisis
failure of neural tube to close-> therfore failure of neurocranium to close which results in brain tissue getting exposed to amniotic fluid which degenerates and results in some type of ancephaly and the fetus is usually not viable.
What is a cranial meningoencephalocele?
The protrusion of the meninges and the brain through a congenital defect in the cranium
What is a meningocele?
the protrusion of the meninges through a congenital defect in the cranium
Is there an epidural space in the brain?
nooo… however there is a potential space
the (blank) forms the periosteum of the interior cranial cavity
dura mater
Where do the meningeal arteries travel in the brain?
within the potential epidural space (i.e lies between the dura and the skull)
Why is there little grooves in the skull?
the meningeal arteries rub against the skull and erode little grooves
Why is the middle meningeal susceptible to damage?
it is superficial and located under a part of the skull that is susceptible to fracture
What are the 2 layers to the dura?
a periosteal layer and a meningeal layer
The 2 layers of the dura sometimes separate on their own to form (blank)
dural sinuses
The diagnostic hallmark of (blank) is:
LUCID INTERVAL.
Patients may have transient unconsciousness.
Patients may regain consciousness, only to relapse suddenly into
unconsciousness (“Talk and Die Syndrome”).
epidural hematoma
What is a potentially deadly condition because of compression of brain and increase in intracranial pressure. 15-20% of patients die of this.
epidural hematoma
What kills you in an epidermal hematoma?
the bleed doesnt, its the fact that it is a space occupying legion which mans there is not place for this legion to go except down through the foramen magnum which will compress the respiratory and cardiovascular center which kills ya :(
(blank) collapses against the brain if the CSF is gone.
arachnoid layer
The transluent membrane on top of the brain is the arachnoid, you can see (blank) piercing through it.
veins
The vessels (cerebral artery and vein) are lining the subarachnoid space until the veins reach the point where they need to penetrate the arachnoid layer and enter into the (blank)
dural sinuses
HOw do the vessels of the brain travel (cerebral artery and vein)?
vessels travel in the subarachnoid space and need to pierce the arachnoid to gain the dural sinuses
(blank) is directly on the surface of the brain, following all sulci and gyri
pia mater
The cerebral veins penetrate the dura to empty into the (blank)
superior sagittal sinus
The subdural space is a potential space that can be filled with a (blank) pressure bleed. The epidural space is a potential space that can be filled with a (blank) pressure bleed.
low
high
What all are dural sinuses made up of?
blood from cerebral veins and CSF from arachnoid granulation
What veins communicate with the scalp and dural sinuses? Why are they important?
emissary veins
can transmit infections from scalp into cranial cavity
What are extensions of meningeal dura called?
dural reflections
The sites where two layers of dura mater split form (blank)
dural sinuses
What are the arachnoid villus?
small protrusions of the arachnoid through the dura mater that protrude into the venous sinuses of the brain, and allow cerebrospinal fluid (CSF) to exit the sub-arachnoid space and enter the blood stream.
What does this describe:
blood occurs quickly in subdural space
occurs mostly in patients with traumatic brain injury (TBI)
often assoc. with other injuries
often assoc. with cerebral edema
poor outcome (50% mortality rate) and sequelae
Acute subdural hematome (acute SDH)
What does this describe: blood appears slowly in subdural space long time course patients often do not remember an injury careful observation or slow drainage outcome is relatively good
Chronic Subdural Hematoma (chronic SDH)
What are the 2 prominant dural reflections in the brain?
Falx (like a mohawk) Tentorium cerebelli (flat across)
What does the Falx cerebri attach to?
part of ethmoid and to the tentorium/cerebellum
Superior sagittal sinus will flow until the (blank)
confluence of sinuses
The inferior sagittal sinus will meet with the (blank).
straight sinus
What is significant about the straight sinus?
it is where the falx meets with the tentorium
Where does the occipital sinus drain into? What is signif about this?
the confluence of sinuses. This is the connection b/w prostate plexus therefore prostate cancer can spread here
Where will the the confluence of sinuses run?
to the transverse sinus into the sigmoid sinus which will ultimately hook up with the internal jugular vein
What is significant about cavernous sinuses?
From top to bottom:
carotid, CN 3, 4, 6, V1, V2
ALl the sinuses ultimately drain into the (blank)
internal jugular vein
What are the 7 sinuses?
superior sagittal inferior sagittal straight conflues transverse sigmoid cavernous
What three things drain to the cavernous sinus? What do we call the collection of these?
opthalamic plexus, pterygoid plexus and facial vein
triangle of death (cuz super prone to infection)
How come the cavernous sinus can drain in different directions?
because it doesnt have valves
You make CSF through the ventricles and this travels out through to the (blank).
subarachnoid space
What are all the ventricle?
2 lateral ventricles
Third ventricle
cerebral aqueduct
fourth ventricle
Which ventricles are C shaped and extend to all lobes of the brain?
the two lateral ventricles
How do you flow from the lateral ventricle to the third ventricle?
via intraventricular foramen of morno
How do you flow from the third ventricle to the fourth?
via the cerebral aqueduct
How do you flow from the fourth ventricle to subarachnoid space?
to the Foramen of Luscka (lateral foramen) and Foramen of Magendie (medial foramen) which let CSF to subarachnoid space
Is the cisterna magna above or below the fourth ventricle?
below the fourth ventricle
Where is the choroid plexus?
above the lat ventricle
How much CSF is produced and where does it go?
What is the capacity for CSF?
400-500 ml/day, most of it is resorbed by the arachnoid granulations.
150 ml
What does CSF do?
functions in buoyancy, nutrition and waste removal
(blank) are places where CNS tissue makes abrupt change in direction and arachnoid follows a smooth course like the Dura creating an enlarged subarachnoid space. (i,e between the pia and the arachnoid)
cisterns
What are the four subarachnoid cisterns?
superior cistern
interpeduncular cistern
pontine cistern
cisterna magna
What is the most important cistern?
cisterna magna
What is hydrocephalus?
excessive accumulation of CSF due to overproduction or inadequate reabsorption reabsorption resulting in dialation of cerebral ventricles and raised intracranial pressure.
What can hydrocephalus cause in infants?
enlargement of cranium and atrophy of brain
What are the 2 blood supplies to the brain?
internal carotid
vertebral
What does the carotid do?
split into external and inernal carotid
What does the internal cartoid artery do?
makes C shaped bend and gives off branches to orbital and contributes to circle of willis
When the verterbal artery busts through the transverse foramina, what does it do?
it merges with the basilar
What are all the components to the circle of willis?
vertebral artery via the basilar and posterior cerebral arteries
posterior communicating
internal cartoid artery via the middle cerebral and anterior cerebral and the anterior communicating
What are the vertebral artery contributions to the circle of willis?
basilar and posterior cerebral artery
What are the internal carotid artery contributions to the circle of willis?
middle cerebral and anterior cerebral
What arteries goes through the middle border of the cerebral fissure? What artery connects these 2?
the anterior cerebral
anterior communicating artery
What is sig about the circle of willis?
it is the last place in the brain where there is potential collateral flow (i,e if block internal carotid or something)
What is a CVA?
cerebrovascular accident
Why do you get a stroke (CVA)?
obstruction or rupture of a cerebral vessel
What are the 2 ischemic strokes?
thrombotic and embolic
What happens if you have a break in a blood vessel in the brain due to an aneurysm?
cerebral hemmorhage (hemorrhagic stroke)
what is crazy about blood and neural tissue?
blood is cytotoxic to neurotissue
What are the three cranial fossae?
anterior
middle
posterior
What is in the anterior cranial fossa?
the frontal lobe
What it is in the middle cranial fossa?
temporal lobe
What is in the posterior cranial fossa?
the occipital lobe and cerebellum
The (blank) is where the brain stem meets up with the cerebral hemispheres
tentorial notch
What is the grayish structure with holes in it at the anterior part of the skull?
cribiform plate
Explain the orientation of the following anterior structures: optic canal foramen rotundum foramen ovale carotid canal superior orbital fissure
optic canal is most anterior with the superior orbital fissure resting on top of that and slightly posteior. The foramen rotundum is just below the superior orbital fissure and slightly posteior. The foramen ovale is the big hole betwee the carotid canal and the foramen spinosum
Which of the following is the largest of the following posterior structures: Which is the deepest? Which is the most superficial? internal acoustic meatus hypoglossal canal jugular foramen
jugular foramen is largest
hypoglossal cana
internal acoustic meatus
What goes through cribiform plate?
tiny oflactory nerves
What goes through the optic canal?
CN 2
What goes through superior orbital fissure?
CN 3 4 6 V1
What goes through the foramen rotundum?
V2
What goes through the foramen ovale?
V3
What goes through the foramen lacerum?
nothing just cartilage
What goes through the internal acoustic meatus?
CN 7 and 8
7 leaves skull, 8 never leaves skull
Wha t passes through the jugular foramen?
CN 9, 10, 11 and jugular vein
Where do the cell bodies of 9 and 10 come from?
medulla
What comes out of the hypoglossal canal?
all roots of CN 12 come out of cranium here
Which cranial nerves are at greatest risk, the ones with a long distance, or the ones with a short distance to travel?
long distance to travel
What nerve exit the brainstem at the skull in the posterior fossa?
Cn 7-12
What nerves exit the brainstem in the posterior fossa and travel intradurally into the middle fossa where they leave the skull?
CN 3-6
Which nerves are very susceptible to damage?
CN 3-6
What can happen at the acoustic meatus?
you can get an acoustic neuroma that will affect your CN 7 and 8 (since they travel in there) and then can further compress 5,6,9,10
