Cranial contents- lecture 3 Flashcards
What are the wrappings around the brain called
meninges
outermost meninge
dura mater
middle meninge
arachnoid
innermost meninge
pia mater
once the ____ is removed, the dura mater is exposed
calvarium (skull cap)
branches of what artery are evident on the surface of the dura mater
middle meningeal a.
the calvarium has grooves in it from what
from the middle meningeal a. branches being sandwiched between it and the dura mater
reflecting the flap of the dura mater exposes what structure
the arachnoid on the surface of the brain
why is the arachnoid collapsed onto the brain
due to the loss of CSF contained within the subarachnoid space
the dura mater is attached to the midline of the skull near what structure
the superior sagittal sinus
the superior sagittal sinus has what structures draining into it near the midline where the dura mater attaches
superficial cerebral vv.
what is the largest of the venous sinuses
superior sagittal sinus
what forms a venous sinus
the separation of dural layers from one another
what are the two layers of the dura mater
endosteal layer and meningeal layer
where does the endosteal layer lie
it remains adherent to the bone in all regions
where does the meningeal layer of the dura lie
it separates and fuses with its counter part to form a dural fold
look at diagram on page 323
what forms the lateral walls of the venous sinus
meningeal layer of dura
Through the meningeal walls, there are processes of what that stick out into the lumen of the venus sinus
processes of the arachnoid and they are called the arachnoid villi
what is the function of the arachnoid villi
filter CSF into the blood to prevent its buildup in the subarachnoid space due to its constant production by the choroid plexus of the ventricular system of the brain
continued growth of the arachnoid villi through the sinus results in their penetration into what
the overlying bone of the skull
what are these depressions from the arachnoid villi called
arachnoid granulations
the meningeal layers of the dura are separated at what
at venous sinuses
the meningeal layers come together to form a series of ____ ____ that do what
dural folds that either separate or support the various lobes of the brain
How many dural folds are there and what are their names
four
- falx cerebri
- falx cerebelli
- tentorium cerebelli
- diaphragma sellae
Falx cerebri attachments
anteriorly to the cristae galli of the ethmoid bone and fuses posteriorly with the horizontal dural fold- the tentorium cerebelli
the posterior fusion of the falx cerebri to the tentorium cerebelli creates what
the straight sinus
the falx cerebri separates what
the two cerebral hemispheres
in the falx cerebris attached margin near the top of the skull is what? and in its free edge located inferiorly?
superior sagittal sinus and inferior sagittal sinus
what does the falx cerebelli separate
the two cerebellar hemispheres
the falx cerebelli has what in its attached margin
occipital sinus
what separates the two cerebral hemispheres from the two underlying cerebellar hemispheres
the tentorium cerebelli
the tentorium cerbelli’s attached edges form what
left and right transverse sinuses
the tentorium cerebelli’s free edge makes what
U-shaped tentorial notch
tentorium cerebelli attachments
anteriorly to the lateral aspects of the anterior and posterior clinoid processes
the tentorium cerebelli forms the lateral wall of what structure
cavernous sinus
what is the diaphragma sellae
a dural fold stretched across the sella turcica (hypophyseal fossa)
attachments of the diaphragma sellae
the anterior and posterior clinoid processes
the diaphragma sellae becomes invaginated by what
the hypophysis that pushes the dura ahead of it as it descends to rest in the hypophyseal fossa of the sphenoid bone
the attached margins of each dural fold exhibits what and what is the exception to this
dural venous sinus; falx cerebrum also has a small venous sinus in its free margin
the venous sinus system of the cranial cavity collects blood drained from where
scalp, bone of the calvarium, superficial and deep brain areas, and the face
what sinuses make up the dural venous sinus system
- superior sagittal sinus
- inferior sagittal sinus
- left transverse sinus
- right transverse sinus
- occipital sinus
- straight sinus
where do the venous sinuses of the dural venous sinus system meet at?
the confluence located opposite the external occipital protuberance
what are other venous sinuses not directly associated with the dural folds
- sigmoid sinus
- cavernous sius
- intercavernous
- sphenoparietal (to cavernous)
- superior petrosal (cavernous to transverse)
- inferior petrosal (cavernous to sigmoid)
all of the sinuses groove the ____ with which they are associated
bones
how does the cavernous sinus communicate with the superficial venous drainage of the face
via the ophthalmic vein
why is the connection between the cavernous sinus with the superficial venous drainage of the face clinically relevant
because infection can spread inward in these valveless vessels
infection may also pass from the scalp via the ____ veins into the ____ ___ sinus
emissary veins into the superior sagittal sinus
the majority of venous blood leaves via the ____ ___ vein
internal jugular vein
the brain is supplied with blood by 4 arteries that leave major vessels in the _______
root of the neck separately
what two arteries ascend to the brain through the transverse foramina of the cervical vertebrae
vertebral arteries
the vertebral arteries fuse to form what
basilar artery
when is the basilar artery formed
after passing into the cranial cavity via the foramen magnum
when the internal carotid aa. and basilar artery meets at the base of the brain, they become connected to one another forming what
an anastomotic arterial circle called the circle of willis and it ensures continuous blood supply
REMINDER TO LOOK AT DIAGRAMS ON PAGES 326 and 327 TO SEE ARTERIAL CIRCLE
how does the internal carotid artery enter the cranial cavity
through the dural roof of the cavernous sinus
what is the first branch off the internal carotid artery
ophthalmic artery
after giving off the ophthalmic artery, the ICA terminates how
by dividing into anterior and middle cerebral aa.
how does the ophthalmic artery enter the orbit
via the optic canal under the optic nerve (CN II)
why is the ophthalmic artery clinically relevant
it is the only artery to supply the retina and a tumor of CN II may occlude the blood supply to the retina or an aneurism of the ophthalmic artery may compress the CN II
-either may result in impaired vision or blindness
How does the ICA enter the base of the skull
via the carotid canal and then passes horizontally within the bone to enter the cavernous sinus via the upper opening of the foramen lacerum
the inferior opening of the foramen lacerum does not allow the ICA to pass through it why
because it is closed in life by fibrocartilage
once inside the cavernous sinus, the ICA exhibits what shape
S-shape (siphon)
what nerve lies lateral to the ICA in the cavernous sinus
abducens nerve (CN VI); both are wrapped in endothelium and bathed in venous blood
the internal carotid artery has 3 parts in the region of the cavernous sinus, what are they
petrous, cavernous, cerebral (diagram on page 328)
