Lecture 4- Osteology and radiology of the brain

Question 1

how many bones does the skull consist of

Answer 1

22

Question 2

shallow depression or hollows

Answer 2

fossae

Question 3

bony tunnels

Answer 3

canals

Question 4

round holes

Answer 4

foramina

Question 5

narrow slit hole

Answer 5

fissues

Question 6

Bones of the skull can be divided into two groups

Answer 6

1) Neurocranium (8 bones)

2) Viscerocranium (14 bones)

Question 7

Neurocranium (8 bones): x

Answer 7

encases/ protects the brain

• Calvaria “skull cap or ‘vault’”, cranial floor (base) and cranial cavity
  *

Question 8

bone formation in the calvaria “skull cap or ‘vauly”

Answer 8

intramembranous ossification

Question 9

bone formation of the cranial floor (base)

Answer 9

endochondrial ossification- starts as cartilage

Question 10

Viscerocranium (14 bones):

Answer 10

facial skeleton and jaw

• bones begin as membrane or cartilage and ossify
• structures develop from pharyngeal arches (1&2)

Question 11

structure of the bones of calvariia

Answer 11

trilaminar arrangement

• Compact (outer table)
• Diploe (spongy bone)
• Compact (inner table)

Question 12

Periosteum covers outer and inner table of skull bones- shrink-wrapped.

Answer 12

Strongly adhere to bone edges at suture line and continuous through suture and outer inner table of same bone

Question 13

• Holes in cranial flood permit

Answer 13

• cranial nerves and blood vessels to enter into and out of neurocranium
  
  • Foramina, fissures and canals

Question 14

bones of the calvaria

Answer 14

• Frontal bone
• Parietal bones
• Greater wing of the sphenoid bone
• Temporal bone
• Occipital bones

Question 15

joints of the calvaria

Answer 15

• coronal suture
• bregma
• sagittal suture
• lamboida suture
• lamda

Question 16

coronal suture

Answer 16

joint qat the front of the skull running horizontally

Question 17

bregma

Answer 17

where the coronal suture and saggital suture meet at the front

Question 18

saggital suture

Answer 18

joint that runs straaight down the skull

Question 19

lamboid suture

Answer 19

equivalent to the coronal suture but at the posterior part of the skull

Question 20

lamda

Answer 20

joint where the lamboidal suture meets the sagittal suture

Question 21

joints of the skull in infants

Answer 21

fontanelles

Question 22

fontanelles

Answer 22

Late areas of unossified membranous gaps between flat bones of calvaria

• Allow for changing skull size and shape during childbirth
• Permit infant brain growth

Question 23

• fontanelles Fuse in …..
  
  • Anterior –
  • Posterior-

Answer 23

• Fuse in early infancy
  
  • Anterior – 18 months- 2 years
  • Posterior- 1-3 months

Question 24

craniosynotosis

Answer 24

• Rare condition= craniosynostosis (early fusion of fontanelles and sutures)

Question 25

why is the anterior fontanelle useful clinically

Answer 25

Clinically useful when examining new-borns and infants

• Slightly convex shape in a healthy baby
• Inspection and gentle palpation of anterior fontanelle can be used to assess intracranial pressure and state of hydration

Question 26

the cranial floor is formed by

Answer 26

• Three bowl shaped depressions form the cranial floor
  
  • Anterior
  • Middle
  • Posterior crania fossae
    *

Question 27

which bones for the cranial floor

Answer 27

• occipital bone- posterior
• temporal
• sphenoid
• ethmoid
• frontal

Question 28

occipital bone forming the posterior cranial floor

Question 29

frontal bone forming the anterior cranial floor

Question 30

ethmoid bone forming the anterior cranial floor

Question 31

sphenoid bone forming the middle cranial floor

Answer 31

Question 32

temporal bone forming the middle cranial floor

Answer 32

Question 33

……. part of temporal bone houses middle and inner ear structures

Answer 33

petrous

Question 34

where is the thinnest part of the brain

Answer 34

pterion

Question 35

pterion

Answer 35

where the different parts of the skull meet

• Important relationship between pterion and underlying blood vessel: middle meningeal (which is between the periosteum and the bone) (Anterior branch)
• Blows to the side of the head can fracture bone in area of pterion and injury blood vessel lying immediately below- intracranial (extra-dural)