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Flashcards in The Skull Deck (33):
1

Functions of the skull?

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

2

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

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

3

What can the cranium be divided into?

Calvaria aka neurocranium which houses the brain - 8 bones
Facial bones - 14

4

Which bones form the cap of the cranium?

Frontal
Parietal
Occipital
Temporal

5

What grooves does the parietal bone have?

Grooves of:
-middle meaningeal artery
-sagittal sulcus
-granular pits
-sigmoid sinus

6

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

Foramen magnum

7

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

Sphenoidal
Ethmoid
Temporal

8

Features of the sphenoid bone?

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

9

What can fracture of the ethmoid bone lead to?

Anosmia (loss of sense of smell)

10

Features of the temporal bone?

Squamous portion
Mastoid process
Mandibular fossa
Zygomatic process
External auditory meatus
Styloid process

11

Features of the ethmoid bone?

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

12

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

C1 (atlas)
Facial bones
Mandible

13

What can the calvaria be divided into?

Cap and floor of calvaria

14

Name the bones of the facial skeleton

Zygomatic
Lacrimal
Nasal
Inferior nasal conchae
Palatine
Vomer
Maxillae
Mandible
Frontal

15

How do most of the bones develop?

Intramembranous ossification

16

What are the main sutures in adulthood?

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

17

What are fontanelles?

Incompletely fused suture joints in neonates

18

Name the fontanelles and the sutures in which they are found

Frontal fontanelle - junction of coronal and saggital
Occipital fontanelle - saggital and lambdoid

19

Why are sutures helpful in neonates?

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

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

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

21

Signs of a cranial fracture?

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

22

Where is the pterion found?
What can happen if it is fractured?

Junction between temporal, parietal, frontal and sphenoid bones

Lacerate Middle meningeal artery causing an extradural haematoma

23

Where are the points of weakness on the skull?

Pterion
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa

24

Which bones form each of the cranial fossas?

Anterior - depression formed by frontal, ethmoidal and parietal

Middle - depression formed by sphenoid, temporal, parietal

Posterior - squamous, mastoid temporal bone, occipital bone

25

Depressed fracture:

What is it?

Cause?

Depression of the bone inwards

Usually by a direct blow

26

What is a linear fracture?

A break traversing the full thickness of the skull

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

Most common

27

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

Basal skull fracture

28

What is a diastatic fracture?

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

29

What is Battle's sign?

Bruising behind ears

30

Clinical features of a facial fracture?

Profuse bleeding
Swelling
Deformity
Anaesthesia of the skin

31

What makes the bones of the skull less easily unlocked?

The edges are serrated

32

Which bones are most frequently broken in a facial fracture?

Nasal

33

What can fracture of the cribriform plate lead to?

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