Osteology and Radiology of the Skull & The TMJ 1 - Terminology + Vault Of Neurocranium

Question 1

How many bones are in the skull?

Answer 1

22

Question 2

What are the two groups of skull bones?
How many bones are in each group?

Answer 2

• neurocranium: 8 bones | encases brain
• viserocrnium: 14 bones | facial skeleton + jaw

Question 3

What are these osteological features?
- fossae
- canal
- foramina
- fissures

Answer 3

• fossae: shallow depressions or hollows
• canal: bony tunnels
• foramina:round holes
• fissures: narrow slits

Question 4

Describe the neurocranium
What are the 3 parts?

Answer 4

• made up of 8 bones
• encase + protect brain

3 parts:
- calvaria: skull cap/vault
- cranial floor: base
- cranial cavity

Question 5

Describe the ossification of the parts of the neurocranium

Answer 5

• intramembranous ossification: vault bones begin as membranes
• endochondrial ossification: floor begins a cartilage

Question 6

Describe the viserocranium

Answer 6

• made of 14 bones
• facial skeleton +jaw
• bones begin as membrane or cartilage >ossify
• structures develop from pharyngeal arches

Question 7

What do vault bones of the neurocranium begin as?
Name this ossification

Answer 7

• membranes
• intramembranous ossification

Question 8

What do floor bones of the neurocranium begin as?
Name this ossification

Answer 8

• cartilage
• endochondrial ossification

Question 9

Name the bones of the calvaria

Answer 9

• frontal bone
• parietal bones
• greater wing of sphenoid bone
• temporal bone
• occipital bones

Question 10

Name the sutures of the neurocanium

Answer 10

• coronal suture
• Sagittal suture
• lambdoid suture

Question 11

What is the coronal suture between?

Answer 11

Frontal bone + paired parietal bones

Question 12

What is the Sagittal suture between?

Answer 12

The two parietal bones

Question 13

What is the lambdoid suture between?

Answer 13

Paired parietal bones + occipital bone

Question 14

What is the bregma?

Answer 14

The intersection between the coronal + Sagittal suture

Question 15

What is the lambda?

Answer 15

The intersection between the Sagittal + lambdoid suture

Question 16

What are fontanelles in the infant skull?

Answer 16

Large areas of unossified membranous gaps between flat bones of calvaria

Question 17

Functions of fontanelles

Answer 17

• allow for alteration of the skull size + shape during childbirth
• permit growth of infant brain

Question 18

Where is the anterior fontanelles located?
When does it fuse?

Answer 18

• Area of the bregma
• 18months - 2 years

Question 19

Where is the posterior fontanelles located?
When does it fuse?

Answer 19

• Area of lambdoid
• 1 - 3 months

Question 20

What is craniosynostosis?

Answer 20

Early fusion of fontanelles + sutures

Question 21

Clinical use of the anterior fontanelles

Answer 21

• slightly convex shape in healthy baby
• gentle palpation can be used to assess intracranial pressure + state of hydration
• high pressure > bulging
• dehydrated > sunken

Question 22

What is a bulging anterior fontanelle a possible sign of?

Answer 22

High intracranial pressure

Question 23

What is a sunken anterior fontanelle a possible sign of?

Answer 23

Dehydration

Question 24

Describe the bones of the calvaria
What is their arrangement?

Answer 24

• mainly flat with a curved surface
• trilaminar arrangement:
• compact bone inner +outer table
• diploe (spongy bone) in middle

Question 25

Describe the trilaminar arrangement of the bones in the calvaria

Answer 25

• compact bone (outer table)
• diploe (spongy bone)
• compact bone (inner table)
• protective strength without adding significant weight

Question 26

What covers the surface of bones?

Answer 26

Periosteum

Question 27

Where does the blood accumulate between when the middle meningeal artery ruptures causing an extra-dural haemorrhage?

Answer 27

Between the inner table of bone + periosteum

Question 28

What features are different in the fetal skull compared with the adult skull?

Answer 28

In the fetal skull:
- fontalles
- absence of erupted teeth
- small nasal cavity, maxilla + mandible
- absence of mastoid + styloid process
- large calvaria relative to face

Question 29

Feature of the sphenoid bone

Answer 29

Sella turcica
Pituitary gland sits within it