Session 2 Flashcards

1
Q

Which suture can be found between the parietal bones?

A

Sagittal Suture

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2
Q

Which suture can be found between the frontal bone and parietal bones?

A

Coronal Suture

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3
Q

What suture can be found between the occipital bone and parietal bone?

A

Lambdoid suture

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4
Q

Which 2 groups can the bones of the skull be broadly divided into?

A

Neurocranium - 8 bones

  • Encase and protect brain
  • Has the Calvaria, Cranial floor base and Cranial cavity

Viscercranium - 14 bones

  • Facial skeleton and the jaw
  • Surround the oral cavity, pharynx and upper respiratory passages
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5
Q

What does the Calvaria begin as and how does it ossify?

A

Begins as membrane and undergoes intramembranous ossification

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6
Q

What does the floor of the neurocranium begin as and by which process does it ossify?

A
  • Cartilage

- Undergoes endochondrial ossification

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7
Q

How do structures within neurocranium communicate with other head and neck structures?

A
  • Cranial floor has holes that enable cranial nerves to allow communication between the brain and brain stem and the structures of the face and neck they innervate.
  • Blood vessels also pass between these holes
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8
Q

What are the 3 bowl shaped depression formed on the cranial floor?

A
  • Anterior Cranial Fossae
  • Middle Cranial Fossae
  • Posterior Cranial Fossae
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9
Q

What is the trilaminar arrangement of the calvaria?

A
Outer Table (compact bone)
Diploeic Cavity (spongy bone)
Inner table (compact bone)
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10
Q

Why are the edges of the bones of the skull serrated?

A

To prevent slippage and movement

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11
Q

When does growth at sutures stop?

A

Puberty

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12
Q

What covers the surface of the outer table of bone?

A

Periosteum

-Strongly adhered at suture line

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13
Q

Periosteum covering the outer table is continuous through to the periosteum covering the inner table. True/False

A

True

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14
Q

Where does a cephalohaematoma occur?

A

Occurs between he periosteum and the bones.

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15
Q

Can bleeding in a cephalohaematoma pass the suture lines?

A

No it cannot.

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16
Q

What are fontanelles?

A

Areas of membrane between bones that are particularly large.

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17
Q

What are the purposes of fontanelles?

A
  • To allow for altering of the skull size and shape during child birth
  • To permit growth of infant brain
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18
Q

When the fontanelles fuse?

A

Posterior - 1 month to 3 months

Anterior - 18 months to 2 years

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19
Q

What is early fusion of fontanelles and sutures called?

A

Craniosyntosis

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20
Q

What is the shape of the fontanelles?

A

Slightly convex shape in a healthy baby

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21
Q

What should be performed in all partients with known or suspected skull fractures?

A

CT scanning should be performed to identify intra cranial injuries

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22
Q

What are the two main types of fractures?

A

Linear - pass full thickness of skull. It is failed strains and involve no bone displacement

Depressed - Fragment is displaced inwards towards the brain

23
Q

What are basilar skull fractures and what are their risks?

A

Fractures involving the cranial base

  • Associated with cranial nerve injuries
  • Prone to causing cerebrospinal fluid leaks
24
Q

Which artery is underlying the Pterion?

A

Middle meningeal artery

25
Q

Why is the pterion particularly at risk of fracture?

A

It is the thinnest area of the skull

26
Q

What is the risk with the pterion?

A

Intracranial Haemorrhage due to the injury to the middle meningeal artery

27
Q

What are some signs of basilar skull fractures?

A
  • Raccoon eyes
  • Battle signs
  • Hemotympanum
28
Q

What the 3 sacs around the brain and their properties?

A

Dura: tough fibrous membrane

Arachnoid: soft translucent membrane

Pia: microscopically thin, delicate and closely adherent to surface of brain

29
Q

Which membranous layers of the brain can be pulled away easily?

A

Dura and Arachanoid

30
Q

The dura is translucent. True/False

A

False. The arachnoid is translucent

31
Q

What are the layers of the dura?

A
Periosteal = endosteum lining the inner bones of skull 
Meningeal = Layers adjacent to arachnoid
32
Q

What is formed by separation of the two layers of the dura?

A
  • Dural folds

- Dural venous sinuses

33
Q

What is the purpose of the dural folds?

A

Helps to stabilise the brain and act as Rigid dividers

34
Q

What are these signs associated with?
A. Sunken fontanelles
B. Bulging fontanelles
C. Enlarged fontanelles

A

A. Sign of dehydration
B. Symptom of serious illness such as meningitits
C. Sign of Down syndrome or premature birth

35
Q

Where can the falx cerebri be found?

A

In the sagittal place. It lies in the midline of the brain

36
Q

Where can the tentorium cerebella be found?

A

In the transverse plane of the brain. It slips between the cerebellum and the brain.

37
Q

What can a rise in pressure inside the skull lead to?

A

Compression and displacement of the brain against the rigid folds and/or through foramen magnum. (herniation)

38
Q

What are the effect of a rise in pressure on the cranial nerves?

A

Their roots have a close relationship with the dural folds so they can get squashed

39
Q

What are dural venous sinuses?

A

Venous blood filled spaces created by separation of meningeal from periosteal layer of the dura.

40
Q

Where do the major venous sinuses lie?

A

At the border of the falx cerebri, falx cerebelli and also on the cranial floor.

41
Q

Where does venous blood from the brain drain to?

A

Venous sinuses via the cerebral veins

42
Q

Where do the dural venous sinuses eventually drain to?

A

Internal jugular vein

43
Q

Which venous sinus runs in the sagittal plane?

A
  • Superior sagital sinus

- Inferior sagital sinus

44
Q

Which venous sinus runs in the transverse plane?

A

-Transverse venous sinus

45
Q

What does the transverse venous sinus change to when it reaches the petrous bone?

A

Sigmoid sinus

46
Q

When does the sigmoid sinus become the internal jugular vein?

A

When it reaches the jugular foramen

47
Q

Where is the confluence of sinuses found?

A

Deep to the protuberance of the occipital bone

48
Q

What is the confluence of sinuses?

A

A meeting point of the straight sinus, superior sagittal sinus and inferior sagittal sinus.

49
Q

How do cerebral veins within the subarachnoid space drain into the dural venous sinuses?

A

Bridging veins

50
Q

What is a common cause of extradural haemorrhage?

A

Arterial bleed via the middle meningeal artery. Bleeding occurs between the bone and periosteal

51
Q

What is a common cause of subdural haemorrhage?

A

Venous bleed through the bridging veins.

52
Q

Why doesn’t the bleed form a subdural haemorrhage spread across the brain?

A

Falx cerebri stops the spread across the side of the brain

53
Q

Why are older people more susceptible to subdural haemorrhage?

A
  • The Brian gets smaller as you get older
  • Increase tension of the bridging veins
  • A slight knock could cause the veins to rupture as a result
54
Q

What usually cause a subarachnoid haemorrhage?

A

-Usually a branch of the circle of willis

Secondary to trauma or spontansous rupture of the blood vessel