Lecture 4 - Osteology

Question 1

Neurocranium

Answer 1

Calvaria
Cranial floor
Cranial cavity

Question 2

Viscerocranium

Answer 2

Facial skeleton

Question 3

8 bones of the neurocranium

vault bones

Answer 3

Frontal
2 x parietal 
2 x temporal 
Occipital 
Sphenoid
Ethmoid

Question 4

How are vault bones developed

Answer 4

By intramembranous ossification

Question 5

How is the cranial floor developed

Answer 5

Endochondrial ossification

Question 6

What does the viscerocranium develop from?

Answer 6

From the pharyngeal arches 1 and 2 - innervated by the facial and trigeminal nerve

Question 7

Sutures

Answer 7

Coronal - between the frontal and parietal bones
Sagittal - between the parietal bones
Lamboid - between the parietal and occipital bones

Question 8

Names of the fontanelles

Answer 8

Bregma

Lambda

Question 9

What are fontanelles?

Answer 9

Large areas of unossified membranous gaps between the flat bones of the calvaria which enable some mobility

Question 10

Uses of fontanelles

Answer 10

Allow movement of calvaria during delivery

Allows growth and development of the brain

Question 11

When do fontanelles fuse

Answer 11

Bregma- 18 months - 2 years

Lambda- 1 - 3 months

Question 12

Craniosynostosis

Answer 12

Early fusion of the fontanelles

Question 13

Why is the bregma clinically usefull

Answer 13

Gentle palpation

• If bulging - high intracranial pressure unless vomiting or crying
• If sunken - dehydrated

Question 14

Trilaminar arrangement of the calvaria bones

Answer 14

Inner and outer table of compact bone

Diploe spongy bone in between

Question 15

Adaptation of the calvaria bones

Answer 15

Compact inner and outer table - protection as strong

Diploe- light weight

Question 16

Periosteum

Answer 16

Covers the surface of the inner and outer tables of the calvaria bones

Strongly adhered to sutures

Question 17

Cranial fossae

Answer 17

Anterior - mostly frontal bone, ethmoid and lesser wing of sphenoid bone

Middle - greater wing of sphenoid and the petrous part of the temporal bone

Posterior - occipital bone

Question 18

Anterior cranial fossa

Answer 18

Contains the orbital plates

The cribriform plate and formina

Question 19

Crista galli

Answer 19

Attachment site of the flax cerebri

Question 20

Middle cranial fossa

Answer 20

Contains the sella turcica
Foramen rotundum 
Foramen ovale
Superior orbital fissure 
Contains the cochlear and semicircular canals

Question 21

Posterior cranial fossa

Answer 21

Contains the foramen magnum

Question 22

Linear skull fracture

Answer 22

Fairly straight

No displacement

Question 23

Comminuted skull fracture

Answer 23

Multiple fracture lines
+/- displacement
Can be depressed in

Question 24

Fractured pterion

Answer 24

Middle meningeal artery is immediately beneath bone therefore high risk of extra dural haemorrhage

Question 25

Extra dural haemorrhage

Answer 25

Intracranial Blood accumulates between the inner table of bone and the periosteal layer of the dura mater Lucid interval Lemon shaped - periosteum strongly adhered to sutures

Question 26

Presentation of basilar skull fractures

Answer 26

Anterior cranial fossa: - Bi-periorbital ecchymosis - CSF rhinorrhea Middle cranial fossa: - Haemotympanum - Battle's sign - CSF otorrhea

Question 27

Basilar skull fracture

Answer 27

Fracture through the base of the skull

Question 28

Bones of the viscerocranium

Answer 28

``` Zygomatic Maxilla Nasal Mandible Lacrimal ```

Question 29

Le fort classification

Answer 29

Fractures to bone of midface: - seperation of midface from skull base - Problems with the airways

Question 30

Cut eyebrow

Answer 30

Supraorbital ridge is very tough therefore doesn't tend to fracture but skin easily tears

Question 31

Common fractures of the face

Answer 31

Nasal bone Zygomatic bone and arch Mandible - normally fractures in 2 places

Question 32

TMJ

Answer 32

Synovial hinge joint Lined by fibrocartilage therefore articular bones do not come into contact with each other Stabilised by joint capsule and extracapsular ligaments Innervated by auriculotemporal nerve (branch of Vc)

Question 33

TMJ conditions

Answer 33

- TMJ disorder - pain around ear, jaw and lateral side of head. Clicking and locking - Dislocation - Arthritis

Question 34

If open mouth wide

Answer 34

Gliding forward action as the mandibular condyle slides onto the articular tubercle

Question 35

If open mouth slightly

Answer 35

Hinge rotation via the inferior half of the TMJ with the madibular fossa

Question 36

Muscles that elevate the mandible

Answer 36

Masseter Temporalis Medial pterygoid

Question 37

Muscles that depress the mandible

Answer 37

Lateral pterygoid

Question 38

Muscles that protrude the mandible

Answer 38

Lateral pterygoid | Medial pterygoid

Question 39

Muscles that retract the mandible

Answer 39

Posterior fibres if the temporalis

Question 40

Dislocation of the TMJ

Answer 40

Jaw locks in open position - anterior dislocation of condyle over the articular tubercle Muscles of mastication keep jaw locked