Intracranial Cavity Flashcards
The intracranial cavity is formed by what bones?
frontal, parietal, temporal, occipital, ethmoid, & sphenoid bones
The intracranial cavity encloses & protects what?
the brain, its meninges, vasculature, & CN
Define the skull, cranium, & calvarium
Skull - full head
Cranium - w/o mandible
Calvarium - bones of the skull excluding the lower jaw & neurocranium (upper & back part of of the skull)
- The roof & base of skull
Label
Label
- Frontal crest
- Crista galli
- Cribriform plate
- Lesser wing
- Anterior clinoid process
- Otic canal
Label
- Superior orbital fissure
- Foramen rotundum
- Formane ovale
- Foramen spinosum
- Foramen lacerum
- Depression for the trigeminal ganglion
- Hiatus of facial canal for the greater petrosal nerve
- Hiatus & groove of the lesser petrosal n.
Label
- Tuberculum sellae
- Hypophyseal fossa
- Dorsum sellae
Describe the sella turcica. What’s the deepest part?
A saddle-shaped depression in the body of sphenoid
Hypophyseal fossa (holds the pituitary gland)
What passes through the superior orbital fissure?
CNs III, IV, VI, V1, ophthalmic veins
What passes through foramen rotundum?
CN V2
What passes through foramen ovale?
CN V3
what passes through foramen spinosum?
Middle meningeal artery
What passes through internal acoustic meatus?
CN VII & VIII
What passes through jugular foramen?
CN IX, X, XI, & internal jugular vein
What passes through hypoglossal canal?
CN XII
What passes through foramen magnum?
CN XI, spinal cord & nerves
Label
- Internal acoustic meatus
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
Label
- Internal acoustic meatus
- Groove for the superior petrosal sinus
- Jugular foramen
- Groove for inferior petrosal sinus
- Hypoglossal canal
What are the 3 layers of the cranial meninges?
Dura mater, arachnoid mater, & pia mater
The dura mater contains
dura mater (periosteal layer), dural sinus, & dura mater (meningeal layer)
The arachnoid mater contains
arachnoid membrane, subarachnoid space, & arachnoid trabeculae
Pia mater is bound to the surface of the brain by
astrocytes
What is within the subarachnoid space?
Cerebrospinal fluid & vessels
CSF nourishes the
CNS
Describe the middle meningeal artery
- Branch of the maxillary artery from external carotid artery
- Supplies cranial bones (calvaria) & dura mater
Where does the middle meningeal artery run through?
Runs through foramen spinosum & lays between dura mater & the calvaria (top part of the skull & covers the cranial cavity)
Rupture of middle meningeal artery leads to
epidural hemorrhage
Anterior branches of the middle meningeal artery runs beneath the
pterion
What is the cranial dura innervation for the following:
- anterior meningeal branches of the anterior ethmoidal nerve
- meningeal branch of maxillary artery
- Nervus spinosum (meningeal branch of mandibular nerve)
- Tentorial nerves (recurent meningeal branch of ophthalmic nerve)
- Anterior ethmoidal nerve
CN V1
CN V2
CN V3
CN V1
CN V1
Function of the dura mater in the cranium
forms the septum & venous system (blood circulation)
What are the 2 layers of the dura?
outer periosteal & inner meningeal layer
What are the 2 vertical dural folds? What do they separate?
- Falx cerebri - separates 2 cerebral hemispheres
- Falx cerebelli - separates 2 cerebellar hemispheres
What are the 2 horizontal dural folds? What do they separate?
- Tentorium cerebelli - separates cerebellum from occipital lobes of cerebrum
- Diaphragma sellae - roof of hypophyseal fossa
Describe an extradural hemorrhage
middle meningeal artery raptured (arterial blood)
Describe a subdural hemorrhage
cerebral veins raptured (venous blood)
Describe a subarachnoid hemorrhage
cerebral arteries rapture (arterial blood)
- blood leaking to CSF
Blood supply to brain comes from
vertebral artery & internal carotid artery
What is the circle of willis?
joining area of several arteries at the bottom (inferior) side of the brain
it forms collateral circulation
What does the circle of willis contain?
anterior communicating artery, anterior cerebral artery, internal carotid artery, posterior communicating artery, posterior cerebral artery
Blood flow within the skull is through
diploic veins
Route of venous blood deep to the skull is from
veins to sinuses
Dural venous sinuses don’t have ___, they only have ___
valves
2 layers
Label
- Superior sagittal sinus
- Inferior sagittal sinus
- Great cerebral vein
- Straight sinus
- Confluence of sinus
Label
- Cavernous sinus
- Sigmoid sinus
- Confluence sinuses
- Transverse sinus
Label
- Cavernous sinus
- Inferior petrosal sinus
- Superior petrosal sinus
Steps from inferior sagittal sinus to internal jugular vein
- Inferior sagittal sinus
- Superior sagittal sinus, OR straight sinus + occipital sinus
- Transverse sinus + superior petrosal sinus (this is from cavernous sinus)
- Sigmoid sinus + infrapetrosal sinus (from cavernous sinus)
Internal jufular sinus
Cavernous sinus drains via the
petrosal sinuses
Define/function of arachnoid granulations
- projections of the arachnoid membrane into the dural sinuses
- allow CSF to pass from subarachnoid space into the venous system
Describe the danger triangle of the face
- Communication between cavernous sinus & surface veins through superior & inferior ophthalmic veins & through pterygoid plexus of veins providing potential routes for an infection from facial area to spread to brain, causing cavernous sinus thrombosis, meningitis & brain abscesses
- Facial vein & cavernous sinus are connected
