The Axial Skeleton

Question 1

Describe the bones that make up the axial skeleton

Answer 1

• there are 80 bones total in the axial skeleton
• skull (22)
• associated bones (7): 2 sets of 3 ear ossicles, hyoid
• post cranial skeleton (51): vertebral column, thoracic cage

Question 2

Describe the function of the human skull

Answer 2

• most complex region of the axial skeleton
• supports and protects the brain and special sense organs
• accommodates the first part of the respiratory and digestive systems
• provides attachment site for muscles of the head and neck

Question 3

Describe the growth of the skull

Answer 3

• ossification is incomplete at birth
• the fontanelles allow for passage through birth canal
• posterior fontanelle closes: 2-9 months
• anterior fontanelle closes: 15-24 months
• timing of closure is highly variable

Question 4

Describe the cranium

Answer 4

• is concurrent with brain development
• brain size at birth = 25% of adult size
• 2 years = 75% by 2 years
• 10 years = adult size

Question 5

Describe the 3 functions of the post cranial axial skeleton

Answer 5

1. Support/transmission of forces
2. Protection of viscera and spinal cord
3. Muscle attachment and movement

Question 6

Describe the hyoid bone

Answer 6

• located at the level of the 3rd cervical vertebra

- muscle attachment

Question 7

Describe the regions of the vertebral column

Answer 7

• Cervical (7), upper C1&C2, lower C3-C7
• Thoracic (12)
• Lumbar (5)
• Sacral (5 fused = sacrum)
• Coccyx ( 4 fused)

Question 8

Describe the 4 types of vertebral curves

Answer 8

Thoracic and Sacral kyphoses = primary curves

Cervical and Lumbar lordoses = secondary curves

Question 9

Describe the 2 types of Intervertebral joints:

Answer 9

Anteriorly = interbody joints 
Posteriorly = zygapophyseal joints

Question 10

Describe the Cervical vertebrae

Answer 10

• small vertebral body
• relatively large vertebral foramen
• transverse foramen (for vertebral artery and vein)
• bifid spinous process
• lateral/ unconvertebral lips on body

Question 11

Describe the Thoracic vertebrae

Answer 11

• medium sized body
• relatively small, round vertebral foramen
• costal facets on the vertebral body
• costal facets on the transverse processes
• long, downward pointing spinous processes

Question 12

Describe the Lumbar vertebrae

Answer 12

• large vertebral body for weight bearing
• relatively small, triangular vertebral foramen
• thick, blunt spinous process

Question 13

Describe the thoracic cage

Answer 13

• ribs, costal cartilages, sternum

- attached posteriorly to vertebral column