Cranial contents- lecture 3

Question 1

What are the wrappings around the brain called

Answer 1

meninges

Question 2

outermost meninge

Answer 2

dura mater

Question 3

middle meninge

Answer 3

arachnoid

Question 4

innermost meninge

Answer 4

pia mater

Question 5

once the ____ is removed, the dura mater is exposed

Answer 5

calvarium (skull cap)

Question 6

branches of what artery are evident on the surface of the dura mater

Answer 6

middle meningeal a.

Question 7

the calvarium has grooves in it from what

Answer 7

from the middle meningeal a. branches being sandwiched between it and the dura mater

Question 8

reflecting the flap of the dura mater exposes what structure

Answer 8

the arachnoid on the surface of the brain

Question 9

why is the arachnoid collapsed onto the brain

Answer 9

due to the loss of CSF contained within the subarachnoid space

Question 10

the dura mater is attached to the midline of the skull near what structure

Answer 10

the superior sagittal sinus

Question 11

the superior sagittal sinus has what structures draining into it near the midline where the dura mater attaches

Answer 11

superficial cerebral vv.

Question 12

what is the largest of the venous sinuses

Answer 12

superior sagittal sinus

Question 13

what forms a venous sinus

Answer 13

the separation of dural layers from one another

Question 14

what are the two layers of the dura mater

Answer 14

endosteal layer and meningeal layer

Question 15

where does the endosteal layer lie

Answer 15

it remains adherent to the bone in all regions

Question 16

where does the meningeal layer of the dura lie

Answer 16

it separates and fuses with its counter part to form a dural fold

look at diagram on page 323

Question 17

what forms the lateral walls of the venous sinus

Answer 17

meningeal layer of dura

Question 18

Through the meningeal walls, there are processes of what that stick out into the lumen of the venus sinus

Answer 18

processes of the arachnoid and they are called the arachnoid villi

Question 19

what is the function of the arachnoid villi

Answer 19

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

Question 20

continued growth of the arachnoid villi through the sinus results in their penetration into what

Answer 20

the overlying bone of the skull

Question 21

what are these depressions from the arachnoid villi called

Answer 21

arachnoid granulations

Question 22

the meningeal layers of the dura are separated at what

Answer 22

at venous sinuses

Question 23

the meningeal layers come together to form a series of ____ ____ that do what

Answer 23

dural folds that either separate or support the various lobes of the brain

Question 24

How many dural folds are there and what are their names

Answer 24

four

1. falx cerebri
2. falx cerebelli
3. tentorium cerebelli
4. diaphragma sellae

Question 25

Falx cerebri attachments

Answer 25

anteriorly to the cristae galli of the ethmoid bone and fuses posteriorly with the horizontal dural fold- the tentorium cerebelli

Question 26

the posterior fusion of the falx cerebri to the tentorium cerebelli creates what

Answer 26

the straight sinus

Question 27

the falx cerebri separates what

Answer 27

the two cerebral hemispheres

Question 28

in the falx cerebris attached margin near the top of the skull is what? and in its free edge located inferiorly?

Answer 28

superior sagittal sinus and inferior sagittal sinus

Question 29

what does the falx cerebelli separate

Answer 29

the two cerebellar hemispheres

Question 30

the falx cerebelli has what in its attached margin

Answer 30

occipital sinus

Question 31

what separates the two cerebral hemispheres from the two underlying cerebellar hemispheres

Answer 31

the tentorium cerebelli

Question 32

the tentorium cerbelli's attached edges form what

Answer 32

left and right transverse sinuses

Question 33

the tentorium cerebelli's free edge makes what

Answer 33

U-shaped tentorial notch

Question 34

tentorium cerebelli attachments

Answer 34

anteriorly to the lateral aspects of the anterior and posterior clinoid processes

Question 35

the tentorium cerebelli forms the lateral wall of what structure

Answer 35

cavernous sinus

Question 36

what is the diaphragma sellae

Answer 36

a dural fold stretched across the sella turcica (hypophyseal fossa)

Question 37

attachments of the diaphragma sellae

Answer 37

the anterior and posterior clinoid processes

Question 38

the diaphragma sellae becomes invaginated by what

Answer 38

the hypophysis that pushes the dura ahead of it as it descends to rest in the hypophyseal fossa of the sphenoid bone

Question 39

the attached margins of each dural fold exhibits what and what is the exception to this

Answer 39

dural venous sinus; falx cerebrum also has a small venous sinus in its free margin

Question 40

the venous sinus system of the cranial cavity collects blood drained from where

Answer 40

scalp, bone of the calvarium, superficial and deep brain areas, and the face

Question 41

what sinuses make up the dural venous sinus system

Answer 41

- superior sagittal sinus - inferior sagittal sinus - left transverse sinus - right transverse sinus - occipital sinus - straight sinus

Question 42

where do the venous sinuses of the dural venous sinus system meet at?

Answer 42

the confluence located opposite the external occipital protuberance

Question 43

what are other venous sinuses not directly associated with the dural folds

Answer 43

- sigmoid sinus - cavernous sius - intercavernous - sphenoparietal (to cavernous) - superior petrosal (cavernous to transverse) - inferior petrosal (cavernous to sigmoid)

Question 44

all of the sinuses groove the ____ with which they are associated

Answer 44

bones

Question 45

how does the cavernous sinus communicate with the superficial venous drainage of the face

Answer 45

via the ophthalmic vein

Question 46

why is the connection between the cavernous sinus with the superficial venous drainage of the face clinically relevant

Answer 46

because infection can spread inward in these valveless vessels

Question 47

infection may also pass from the scalp via the ____ veins into the ____ ___ sinus

Answer 47

emissary veins into the superior sagittal sinus

Question 48

the majority of venous blood leaves via the ____ ___ vein

Answer 48

internal jugular vein

Question 49

the brain is supplied with blood by 4 arteries that leave major vessels in the _______

Answer 49

root of the neck separately

Question 50

what two arteries ascend to the brain through the transverse foramina of the cervical vertebrae

Answer 50

vertebral arteries

Question 51

the vertebral arteries fuse to form what

Answer 51

basilar artery

Question 52

when is the basilar artery formed

Answer 52

after passing into the cranial cavity via the foramen magnum

Question 53

when the internal carotid aa. and basilar artery meets at the base of the brain, they become connected to one another forming what

Answer 53

an anastomotic arterial circle called the circle of willis and it ensures continuous blood supply

Question 54

REMINDER TO LOOK AT DIAGRAMS ON PAGES 326 and 327 TO SEE ARTERIAL CIRCLE

Question 55

how does the internal carotid artery enter the cranial cavity

Answer 55

through the dural roof of the cavernous sinus

Question 56

what is the first branch off the internal carotid artery

Answer 56

ophthalmic artery

Question 57

after giving off the ophthalmic artery, the ICA terminates how

Answer 57

by dividing into anterior and middle cerebral aa.

Question 58

how does the ophthalmic artery enter the orbit

Answer 58

via the optic canal under the optic nerve (CN II)

Question 59

why is the ophthalmic artery clinically relevant

Answer 59

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

Question 60

How does the ICA enter the base of the skull

Answer 60

via the carotid canal and then passes horizontally within the bone to enter the cavernous sinus via the upper opening of the foramen lacerum

Question 61

the inferior opening of the foramen lacerum does not allow the ICA to pass through it why

Answer 61

because it is closed in life by fibrocartilage

Question 62

once inside the cavernous sinus, the ICA exhibits what shape

Answer 62

S-shape (siphon)

Question 63

what nerve lies lateral to the ICA in the cavernous sinus

Answer 63

abducens nerve (CN VI); both are wrapped in endothelium and bathed in venous blood

Question 64

the internal carotid artery has 3 parts in the region of the cavernous sinus, what are they

Answer 64

petrous, cavernous, cerebral (diagram on page 328)