The Skull Flashcards

1
Q

Functions of the skull?

A

Enclose and protect brain and special sense organs
Create a specialised environment in which the brain can thrive (cranial cavity)
Attachment of muscle and meninges

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2
Q

What are the three layers of the bones in the cranium?

A

Outer plate - compact bone
Diploe- reduces the weight
Inner plate - compact bone

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3
Q

What can the cranium be divided into?

A

Calvaria aka neurocranium which houses the brain - 8 bones

Facial bones - 14

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4
Q

Which bones form the cap of the cranium?

A

Frontal
Parietal
Occipital
Temporal

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5
Q

What grooves does the parietal bone have?

A

Grooves of:

  • middle meaningeal artery
  • sagittal sulcus
  • granular pits
  • sigmoid sinus
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6
Q

What are the four parts of the occipital bone arranged around?

A

Foramen magnum

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7
Q

Which bones form the floor of the calvaria? (Aka cranial fossa, cranial base)

A

Sphenoidal
Ethmoid
Temporal

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8
Q

Features of the sphenoid bone?

A

Has the sphenoid sinus
Greater and lesser wings
Pterygoid process
Optic groove

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9
Q

What can fracture of the ethmoid bone lead to?

A

Anosmia (loss of sense of smell)

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10
Q

Features of the temporal bone?

A
Squamous portion
Mastoid process 
Mandibular fossa
Zygomatic process
External auditory meatus
Styloid process
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11
Q

Features of the ethmoid bone?

A
Allows passage of olfactory nerve fibres
Cribriform plate
Crista galli
Ethmoid bulla
Ethmoid air cells
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12
Q

What do the bones of the cranial base provide articulation for?

A

C1 (atlas)
Facial bones
Mandible

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13
Q

What can the calvaria be divided into?

A

Cap and floor of calvaria

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14
Q

Name the bones of the facial skeleton

A
Zygomatic
Lacrimal
Nasal
Inferior nasal conchae
Palatine
Vomer
Maxillae
Mandible 
Frontal
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15
Q

How do most of the bones develop?

A

Intramembranous ossification

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16
Q

What are the main sutures in adulthood?

A

Coronal suture - between frontal and parietals
Saggital - between both parietals
Lambdoid - occipital with parietals
Visualise it!

17
Q

What are fontanelles?

A

Incompletely fused suture joints in neonates

18
Q

Name the fontanelles and the sutures in which they are found

A

Frontal fontanelle - junction of coronal and saggital

Occipital fontanelle - saggital and lambdoid

19
Q

Why are sutures helpful in neonates?

A

They are open so allow for cranial bones to be pushed together during labour
Serrated edges of the bones can temporarily interlock to protect the brain from injury

20
Q

What can happen if the baby is premature concerning the skull?

A

Sutures are too wide
Pressure from birthing does not result in interlocking of bones
Chance of brain damage

21
Q

Signs of a cranial fracture?

A
CSF draining from ears/nose - base of skull fracture
Poor balance
Confusion 
Slurred speech
Stiff neck
22
Q

Where is the pterion found?

What can happen if it is fractured?

A

Junction between temporal, parietal, frontal and sphenoid bones

Lacerate Middle meningeal artery causing an extradural haematoma

23
Q

Where are the points of weakness on the skull?

A

Pterion
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa

24
Q

Which bones form each of the cranial fossas?

A

Anterior - depression formed by frontal, ethmoidal and parietal

Middle - depression formed by sphenoid, temporal, parietal

Posterior - squamous, mastoid temporal bone, occipital bone

25
Q

Depressed fracture:

What is it?

Cause?

A

Depression of the bone inwards

Usually by a direct blow

26
Q

What is a linear fracture?

A

A break traversing the full thickness of the skull

Get radiating (stellate) fracture lines away from point of impact

Most common

27
Q

Someone presents with bruising behind ears and eyes - what do you suspect?

A

Basal skull fracture

28
Q

What is a diastatic fracture?

A

One that occurs along the suture line which widens the suture
Most commonly seen in children

29
Q

What is Battle’s sign?

A

Bruising behind ears

30
Q

Clinical features of a facial fracture?

A

Profuse bleeding
Swelling
Deformity
Anaesthesia of the skin

31
Q

What makes the bones of the skull less easily unlocked?

A

The edges are serrated

32
Q

Which bones are most frequently broken in a facial fracture?

A

Nasal

33
Q

What can fracture of the cribriform plate lead to?

A

If it involves the dura mater, leakage of CSF fluid out of the nostrils
Anosmia if it damages CNI