Cranium

Question 1

Outline

Answer 1

At birth + during infancy, bony plates making up cranium are separated from each other by two natural membrane-covered spaces called fontanelles - allow growth of brain without bony restriction

Question 2

During growth

Answer 2

the spaces gradually become filled with bone + close together to provide a protective helmet surrounding brain. the bony plates join together like jigsaw at the coronoid sutures

Question 3

By age 18 months

Answer 3

the fontanelles should have closed completely, following natural growth together of bony plates making up the cranium

Question 4

The cranium

Answer 4

is composed of 8 bones which are separated by coronoid sutures - these are visible on dry skull as zig-zagged joints between bony plates

Question 5

Frontal bone

Answer 5

single plate at the front of cranium above eyes, forming the forehead

Question 6

Pariental bones

Answer 6

pair of plates forming top + greater area of the sides of the cranium

Question 7

Temporal bones

Answer 7

pair of fan-shaped plates in temple region of the lower sides of cranium, in front of the ears

Question 8

Occipital bone

Answer 8

single plate at back + partial underside of the cranium

Question 9

Sphenoid bone

Answer 9

single plate forming the majority of the base (underside) of the cranium

Question 10

Ethmoid bone

Answer 10

single plate at the front base section of the cranium, immediately behind the nose

Question 11

All the sensory nerve cells

Answer 11

running from body to brain + motor nerves running from brain to body have to pass in + out of this bony cavity through the natural foramina on the underside of the cranium

Question 12

Similarly, all blood vessels supplying head + neck structures

Answer 12

pass through these same foramina or between natural spaces between adjacent bones called fissures

Question 13

In addition to these bony openings,

Answer 13

some cranial bones also have various bony projections + plates on their outer surfaces, which serve as attachments for ligaments + muscles associated with head + jaw movements or which form part of various facial structures

Question 14

The largest foramen of all in cranium

Answer 14

is the foramen magnum, which opens through the occipital bone + allows exit of spinal cord from the base of the brain + into the vertebral column of the spine

Question 15

The 12 pairs of nerves

Answer 15

that branch of directly from the underside of the brain itself, and which supply head + neck region are called cranial nerves