Cranial Cavity Flashcards
what makes up the floor of the cranial cavity?
parts of the frontal, ethmoid, temporal, sphenoid, parietal, and occipital bones
in which cranial fossae does the frontal lobe lie?
anterior cranial fossa
in which cranial fossae does the temporal loeb lie?
middle cranial fossae
what lies in the posterior cranial fossae?
cerebellum and part of the brain stem
what bones is the anterior cranial fossa made up of?
- frontal
- ethmoid
- sphenoid (lesser wings)
what are some of the prominent features of the anterior cranial fossa?
- frontal crest of the frontal bone
- crista galli of ethmoid
- cribiform plate of ethmoid bone
- orbital portion of frontal bone
- lesser wings of sphenoid
- anterior clinoid process of sphenoid
- optic canal (opening in the sphenoid bone)
in which cranial fossa does the frontal crest of the frontal bone lie?
anterior cranial fossa
in which cranial fossa does the crista galli of ethmoid bone lie?
anterior cranial fossa
in which cranial fossa does the cribiform plate of the ethmoid bone lie?
anterior cranial fossa
in which cranial fossa does the orbital portion of frontal bone lie?
Anterior cranial fossa
in which cranial fossa does the lesser wings of sphenoid bone lie?
anterior cranial fossa
in which cranial fossa does the anterior clinoid processes of the sphenoid bone lie?
anterior cranial fossa
in which cranial fossa does the optic canal opening lie?
Anterior cranial fossa
what bones make up the middle cranial fossa?
parts of the
- sphenoid
- temporal
- parietal bones
in which cranial fossa does the cavernous sinus lie?
middle cranial fossa
in which cranial fossa does the body and greater wings of the sphenoid (including the sella turcica) lie?
middle cranial fossa
in which cranial fossa does the anterior portion of the petrous temporal bone (including the tegmen tympani) lie?
middle cranial fossa
in which cranial fossa does the superior orbital fissue lie?
middle cranial fossa
in which cranial fossa does the foramen rotundum lie?
middle cranial fossa
in which cranial fossa does the foramen ovale lie?
middle cranial fossa
in which cranial fossa does the foramen spinosum lie?
middle cranial fossa
in which cranial fossa does the foramen lacerum lie?
middle cranial fossa
in which cranial fossa does the opening of the carotid canal lie?
middle cranial fossa
in which cranial fossa does the groove for middle meningeal artery lie?
middle cranial fossa
in which cranial fossa does the groove and hiatus for greater petrosal nerve lie?
middle cranial fossa
in which cranial fossa does the groove and hiatus for lesser petrosal nerve lie?
middle cranial fossa
what bones make up the posterior cranial fossa?
parts of
- temporal
- occipital
- sphenoid
- parietal bones
in which cranial fossa does the clivus lie?
posterior cranial fossa
in which cranial fossa does the posterior part of the petrous temporal bone lie?
posterior cranial fossa
in which cranial fossa does the internal occipital protuberance lie?
posterior cranial fossa
in which cranial fossa does the foramen magnum lie?
posterior cranial fossa
in which cranial fossa does the internal acoustic meatus lie?
posterior cranial fossa
in which cranial fossa does the jugular foramen lie?
posterior cranial fossa
in which cranial fossa does the hypoglossal canal lie?
posterior cranial fossa
in which cranial fossa does the groove for the inferior petrosal sinus lie?
posterior cranial fossa
in which cranial fossa does the groove for transverse sinus lie?
posterior cranial fossa
in which cranial fossa does the groove for sigmoid sinus lie?
posterior cranial fossa
what are the two layers of the dura mater?
periosteal and meningeal
what are dural sinuses?
venous structures that form where the two layers of the dura mater split
-essentiall a “vein” within the dura (contains venous blood)
is the dura of the brain continuous with the dura of the spinal cord?
you bet it is!
what are dural partitions
formed by the dura, separate parts of the brain
what is the falx cerebri attached to?
crista galli, frontal crest, and tentorium cerebelli
what does the falx cerebri separate?
the right and left cerebral hemispheres
what is the tentorium cerebelli attached to?
occipital bone and petrous ridge of temporal bone
what does the tentorium cerebelli separate?
cerebeullum and occipital lobes
what does the falx cerebelli attach to?
tentorium and internal occipital crest
what does the falx cerebelli separate?
right and left cerebellar hemispheres
what does the diaphragma sellae cover? what passes through it? what type of structure is it?
a dural partition;
covers the hypohyseal fossa and the infundibulum of the pituitary gland passes through a hole in it
between what layers of the skull do the meningeal arteries lie between?
skull + dural
is the dura vascularized?
YES! well supplied by arteries, specifically the middle meningeal artery (from the maxillary artery)
where does the middle meningeal artery enter the skull? what region of the skull does it cross?
enters the skull through the foramen spinosum and crosses the region of the pterion
what nerves innervate the dura?
branches of the trigeminal never (V1 mainly) and upper cervical nerves
what layer (s) of the meninges enter the grooves of the brain?
ONLY PIA (not arachnoid)
what are arachnoid granulations?
They protrude into the dural sinuses of the brain (contain venous blood), and absorb CSF so that CSF can exit the sub-arachnoid space and enter the blood stream.
-large granulations projecting into the superior sagittal sinus
what layer of the skull contains the CSF?
subarachnoid space
where is the pia mater located? what is unique to the pia mater?
right on the surface of the brain
it enters all the grooves and fissures of the brain
where is the extradural space located?
between the skull and dura (potential space)
where is the subdural space located?
between the dura and arachnoid (potential space)
where is the subarachnoid space located?
actual space between arachnoid and pia mater; filled with CSF
what is the course of cerebral spinal fluid (where is it made and to what/through what does it flow)?
formed within in the ventricles of the brain (spaces within the cerebrum and brain stem); leaves the ventricular system through specific foramina and passes into the subarachnoid space; flows around the brain and spinal cord
when does cranial swelling occur?
when CSF can’t drain
what are the little depression in the skull formed by?
arachnoid granulations
what is the purpose of arachnoid granulations?
transfer CSF from the subarachnoid space to the dural sinus (for venous drainage)
describe the path of the vertebral arteries
- arise from the subclavian artery
- pass through the transverse foramen of the cervical vertebrae 6-1
- traverse posterior arch of atlas
- enter the foramen magnum
- right and left vertebral arteries come together to form the basilar artery
what does the vertebral artery supply?
branches supply the spinal cord and cerebellum
what does the basilar artery supply?
cerebeullum and brain stem
what branch does the basilar artery give rise to?
posterior cerebral arteries
describe the path of the internal carotid artery
- enters the skull through carotid canal
- crosses foramen lacerum (DOESNT GO THROUGH IT)
- passes through cavernous sinus
- occupies groove in the sphenoid bone
- turns up and back forming an “S” shaped carotid siphon
what are the branches of the internal carotid artery?
- opthalamic
- posterior communicating
- middle cerebral
- anterior cerebral
(called the internal carotid until it splits totally into the anterior and middle cerebral arteries)
what does the posterior communicating artery connect?
connects the internal carotid artery and the posterior cerebral artery
What does the anterior communicating artery connect?
the two anterior cerebral arteries
what the cerebral arterial circle (of willis) encircle?
pituitary gland
what does the cerebral arterial circle (of willis) contain?
basically an anastomoses between the internal carotid and vertebral artery branches around the pituitary gland (therefore a blockage would not cause a stroke)
-made up of the anterior communicating, anterior cerebral, internal carotid, posterior cerebral, and posterior communicating arteries
what is the carotid siphon?
a portion of the internal carotid artery from the carotid canal until it divides into the medial and anterior cerebral arteries
-it is a site of stenosis and is a landmark on radiological images
what is unique to the structure of the veins in the cranial cavities?
DONT HAVE VALVES
what is the significance of the valve-less veins of the cranial cavity?
allows for blood flow in either direction; thus infection or cancers from elsewhere can spread to the brain easily
what does the cerebral, cerebellar, and brain stem veins drain? where do they empty blood?
they drain the brain and brain stem; empty into the dural sinuses
what is the great cerebral vein (of Galen) drain into?
its a large vein that drains into the straight sinus (drains the brain and the brainstem)
what do the diploic veins drain? where do they empty?
drain the bones of the skull and empty into the dural venous sinuses
**diploic = spongy bone between the two layers of compact bone
what do emissary veins connect?
connect areas outside of the cranial cavity (ie: scalp and pterygoid plexus) to the dural sinuses
where are dural sinuses located?
endothelial lined spaces between the periosteal and meningeal layers of dura
what is the function of the dural sinuses?
a system of valveless veins; the blood and CSF from the sinuses ultimately ends up in the internal jugular vein
where do the dual sinuses empty into?
internal jugular vein
where is the superior sagittal sinus located
in the superior border of the falx cerebri
what drains into the superior sagittal sinus
cerebral, diploic, and emissary veins
also, the arachnoid granulations
what does the superior sagittal sinus drain into?
the confluence of sinuses
where is the inferior sagittal sinus located?
in the lower border of the falx cerebri
what drains into the inferior sagittal sinus
a few cerebral veins
what does the inferior sagittal sinus drain into?
straight sinus
where is the straight sinus located?
at the junction of the falx cerebri and tentorium cerebelli
what drains into the straight sinus?
the great cerebral vein (of galen), and the inferior sagittal sinus
what does the straight sinus drain into?
the confluence of sinuses
where is the occipital sinus located?
falx cerebelli
what drains into the occipital sinus?
vertebral venous plexus
what does the occipital sinus drain into?
confluence of sinuses
where is the confluence of sinuses located?
it is a space at the internal occipital protuberance
what drains into the confluence of sinuses
superior sagittal, straight, and occipital sinuses
what does the confluence of sinuses drain into?
the right and left transverse sinuses
where is the transverse sinuses located?
run along the posterior and lateral attachments of the tentorium cerebelli
what drains into the transverse sinuses?
superior petrosal sinuses, cerebral, and cerebellar veins; superior sagittal sinus goes to right transverse sinus; straight sinus to the left transverse sinus
what does the transverse sinuses drain into?
sigmoid sinuses
where are the sigmoid sinuses located?
between the transverse sinues and internal jugular veins
what drains into the sigmoid sinuses
transverse sinus and other veins
where does the sigmoid sinuses drain into?
the internal jugular vein at the jugular foramen
where are the cavernous sinuses located?
along the lateral side of the body of the sphenoid
what passes through the cavernous sinuses
internal carotid artery and abducent nerve
what drains into the cavernous sinuses
cerebral veins, ophthalmic veins, and emissary veins; also sphenoparietal sinuses
what does the cavernous sinuses drain into?
superior petrosal sinuses and inferior petrosal sinuses
how do infections travel into the cranial cavity via the cavernous sinuses?
because they are connected to each other, to ophthalmic veins and to emissary veins from the pterygoid plexus in the IT fossa (outside of the cranial cavity); Thus infections can pass from outside to the cranial cavity inside
what do the intercavernous sinuses connect?
right and left cavernous sinuses
where are the sphenoparietal sinuses located?
along the lesser wing of the sphenoid bone
what do the sphenoparietal sinuses drain?
diploic veins
where are superior petrosal sinuses located?
along the ridge of the petrous bone and
what do the superior petrosal sinuses drain?
the cavernous sinuses
where do the superior petrosal sinuses drain into?
transverse sinus
where are the inferior petrosal sinuses located?
in the groove between petrous temporal bone and occipital bone
what do the inferior petrosal sinuses drain?
the cavernous sinuses and other veins
where do the inferior petrosal sinuses drain into?
the internal jugular veins
where is the basilar sinus located?
on the clivus of the occipital bone
what does the basilar sinus connect? and what does it communicate with
connects inferior petrosal sinuses and communicates with the vertebral venous plexus
what structures are found in the lateral wall of the cavernous sinus?
oculomotor nerve (III), trochlear nerve (IV), ophthalmic division of the trigeminal (V1) and the maxillary division of the trigeminal (V2)
Extradural Intracranial hemorrhage: where does it occur? what is it usually caused by? symptoms?
bleeding between the dura and the skull
- caused by tearing of middle meningeal artery due to head injury
- symptoms: brief unconscousness, lucid period, then rapid drowsiness and unconscious
Subdural Intracranial hemorrhage: where does it occur? what is it usually caused by? symptoms?
bleeding between the dura and arachnoid
- caused by torn cerebral vein where they enter the superior sagittal sinus
- usually occurs in very young and elderly or due to trauma (weak veins)
- symptoms: injury may seem minor; insidious loss of consciousness/change in personality
subarachnoid Intracranial hemorrhage: where does it occur? what is it usually caused by? symptoms?
between arachnoid and pia mater
- caused by aneurysm of vessels of arterial circle
- due to trauma
