Cranial cavity Flashcards

1
Q

Describe the three layers of the meninges?

A

Dura mater: outer, tough, fibrous

Arachnoid mater: More delicate, fibrous

Pia mater: Thin layer

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2
Q

What are each of the three layers of the meninges connected to?

A

Dura mater: Attached to skull
Arachnoid mater: Lines inner of dura

Pia mater: Lines brain tissue

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3
Q

Describe the spaces created by each of the three meninges?

A

Epidural space: between dura and skull, potential space

Subdural space: between dura and arachnoid, potential space

Subarachnoid space: between arachnoid and pia, occupied by CSF

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4
Q

What can accumulate in the epidural space and when?

A

Blood collects here when meningeal artery ruptures

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5
Q

What occupies the subarachnoid space?

A

CSF

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6
Q

What can accumulate in the subdural space and when?

A

Blood collects here as a result of venous bleeding

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7
Q

List the dural petitions that project into the cranial cavity?

A

Falx cerebri

Tentorium cerebelli

Falx cerebelli

Diaphragma sellae

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8
Q

How far into the brain do the dural petitions project into the cranial cavity?

A

Not all the way; don’t cut the brain into component parts

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9
Q

What is the purpose of the dural petitions?

A

Lodge into the brain partway and restrict rotatory displacement of the brain

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10
Q

Describe the shape of the falx cerebri?

A

Sickle shaped

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11
Q

Where does the falx cerebri lie?

A

In midline between the two hemispheres

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12
Q

Describe the attachments of the falx cerebri?

A

Attaches to inside of skull, immediately along line of sagittal suture Pegs to crista galli anteriorly Attaches posteriorly to internal aspect of occipital protuberance

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13
Q

Describe the shape of the tentorium cerebelli?

A

Crescent shaped, tented upwards

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14
Q

Where does the tentorium cerebelli lie?

A

Roofs over posterior cranial fossa, between cerebral hemispheres above and cerebllum below

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15
Q

Where does the falx cerebelli lie?

A

Between cerebellar hemispheres, beneatch tentorium cerebelli

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16
Q

Describe the orientation of the falx cerebelli?

A

Vertical

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17
Q

Where does the diaphragma sellae lie?

A

Roofs over the sella turcica (pituitary) Lines internal aspect of sphenoid bone and goes across pit

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18
Q

How are the projections of the meninges formed?

A

Dura is a double layered structure; layers are usually stuck together Projections are formed when the inner layer separates from the outer layer, and meets with the inner layer from the other side

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19
Q

Where do the veins that drain the brain eventually end up?

A

Dural venous sinuses

20
Q

Describe the structure of the dural venous sinuses?

A

Endothelial lined spaces Between inner and outer layer of dura when they come apart to form projections Walls are dura

21
Q

Where do the dural venous sinuses lie in relation to the dural layers?

A

Between inner and outer layer of dura when they come apart to form projections

22
Q

What do the dural venous sinuses receive?

A

Veins draining the brain

Diploic veins

Emissary veins

23
Q

What do diploic veins drain?

A

The diploie (spongy bone)

24
Q

What do emissary veins drain?

A

Scalp

25
Q

Why are scalp wounds treated with caution?

A

Any infection here can cause meningitis, as it is a very short trip to encephalitis, due to the venous communications

26
Q

What are the major dural venous sinuses?

A

Superior sagittal sinus

Inferior sagittal sinus

Straight sinus

Transverse sinus

Sigmoid sinus

Cavernous sinus

27
Q

What is the confluence of sinuses?

A

Point where the superior and straight sinuses meet

28
Q

How is the straight sinus formed?

A

Where the inferior saggital sinus meets the Great cerebral vein

29
Q

Where does the transverse sinus run?

A

In the root of the attachment of the tentorium cerebelli

30
Q

What happens at the point of confluence?

A

Sometimes venous blood mixes, other times it doesn’t

31
Q

Where does the sigmoid sinus begin?

A

At the point where the tentorium meets the petrous part of the temporal bone

Transverse sinus becomes sigmoid sinus

32
Q

Describe the course of the sigmoid sinus?

A

Snakes down from tentorium cerebelli in an s-shaped fashion towards the jugular foramen

33
Q

What does the sigmoid sinus exit the jugular foramen as?

A

Internal jugular vein

34
Q

Where does the cavernous sinus lie?

A

Either side of body of sphenoid

35
Q

What is important about the cavernous sinus?

A

Important structures run through it to access their foraminae and exit the skull

36
Q

How is the cavernous sinus different to the other dural venous sinuses?

A

It is not associated with any dural septa

37
Q

Which is the most important meningeal artery?

A

Middle meningeal artery

38
Q

What do the meningeal arteries supply?

A

Bone and meninges of skull

39
Q

What is the middle meningeal artery a branch of?

A

Maxillary artery

40
Q

How does the middle meningeal artery enter the skull?

A

Foramen spinosum

41
Q

What happens to the middle meningeal artery after it branches from the maxillary artery?

A

Divides into anterior and posterior divisions, which groove the bone

42
Q

Where does the medial meningeal artery liein relation to the meninges?

A

In the extradural space

43
Q

What is the outcome of a tear in the middle meningeal artery?

A

Extradural haemorrhage

44
Q

Why is an extradural haemorrhage due to a tear in the MMA so dangerous?

A

Pulsing blood from the artery

With every pulse, more blood gathers

No give in skull > pressure builds quickly

45
Q

Where do the superior cerebral veins drain into?

A

Superior sagittal sinus

46
Q

What is the most common cause of a subdural haemorrhage?

A

Tearing of veins at the point where they enter the superior sagittal sinus after a fall or head trauma

47
Q

Why is a subdural haemorrhage due to a tear in the superior cerebral veins less dangerous than an extradural haemrrhage due to a tear in the MMA?

A

Much lower pressure blood