Axial Skeleton

Question 1

axial skeleton

Answer 1

80 bones that lie on longitudinal axis

includes: skull, hyoid, vertebrae, ribs, sternum, auditory ossicles

Question 2

bones of the skull

Answer 2

22 separate bones connected by immovable joints
6 auditory ossicles
hyoid bone - not attached

Question 3

cranial bones

Answer 3

8 of 22 bones of the skull
2 parietal
2 temporal
1 frontal
1 occipital
1 sphenoid
1 ethmoid

Question 4

facial bones

Answer 4

14 of 22 bones of the skull
2 maxilla
2 zygomatic
2 palatine
2 lacrimal
2 nasal
2 inferior nasal conchae
1 vomer
1 mandible

Question 5

frontal bone

Answer 5

forehead
roof of orbit
ant portion of cranial floor

Question 6

parietal bones

Answer 6

sides and rood of cranial cavity

Question 7

occipital bone

Answer 7

most of base of cranium

Question 8

temporal bones

Answer 8

lateral aspects and part of floor of cranial cavity

Question 9

sphenoid bone

Answer 9

butterfly shape w greater and lesser wings

lateral skull and cranial floor and portion of orbit

Question 10

external auditory meatus

Answer 10

canal found on temoral bone

reaches inner and middle ear structures

Question 11

mastoid process

Answer 11

attachment point for muscles on temporal bone

Question 12

styloid process

Answer 12

attachment point for muscles on temporal bone

Question 13

zygomatic bones

Answer 13

cheekbones and portions of orbit

Question 14

maxilla bones

Answer 14

upper jaw, floor of orbit, hard palate

cleft palate: maxillary bones don’t fuse together during embryologic development

Question 15

occipital condyles

Answer 15

articulate with C1 vertebrae

allow movements of nodding head and lateral tilting of head side to side

Question 16

hyoid bone

Answer 16

unpaired - does not articulate w any other bone

• floats under mandible
• attachment point for tongue muscles
• attachment point for neck muscles that elevate larynx during speech and swallowing

Question 17

vertebral column

Answer 17

- allows for lots of movements for head and trunk
26 vertebrae:
- 7 cervical (convex)
- 12 thoracic (concave)
- 5 lumbar (convex)
- 1 sacral - 5 fused (concave)
- coccygeal - 4-6 fused (concave)

Question 18

which portions of vertebral column are concave and which portions are convex? why and when does this change occur?

Answer 18

only concave curves when first born

• 3 months when lifting head: cervical become convex
• 6-12 months: sitting and walking: lumbar vertebrae become convex

Question 19

what’s the difference between a concave and convex curve?

Answer 19

concave - curves backwards

convex - curves forwards

Question 20

C1 vertebrae

Answer 20

atlas
- holds skull on vertebrae
- no body or spinous processes
- articulates w occipital condyles at superior articular facet
- very large vertebral foramen
allows for forward and lateral flexion

Question 21

C2 vertebrae

Answer 21

axis
- has small body and spinous process (spinous processes form form here and downwards w exception to C7)
Dens: sticks out of body region like a trailer hitch
- ligaments hold in place w C1
- allows for pivot movements

Question 22

thoracic vertebrae

Answer 22

• spinous processes get much shorter, more square in lower region, limits movement here

Question 23

lumbar vertebrae

Answer 23

body and spinous processes are much larger and thicker in this region bc larger muscles attach here
- vertebrae are locked in place to prevent lateral movement

Question 24

sacrum

Answer 24

starts fusing age 16-20, fully fused by 30
- sacral hiatus: where 5th vertebrae didn’t fuse all the way, spinal cord exits here and filium terminale fuses to coccyx

Question 25

coccyx

Answer 25

starts fusing age 20, fully fused by age 30

vertebrae are really just flattened disks of bone

Question 26

intervertebral disks

Answer 26

outside: annulus fibrosis - fibrocartilage layer
inside: nucleus pulposus - gelatinous mass
- provide support and shock absorption, permit movements
- bc made of water and contain cartilage, disks can get compressed as we age thus we get shorter

Question 27

what does it mean if something is herniated?

Answer 27

structure on the outside is broken and inside structure pushes out

• can occur in intervertebral disks due to squishing of front half as a result of anterior movements
• causes break through annulus fibrosis and pulp squishes out into space where spinal cord and nerves are: can result in impingement = pain and reduced function

Question 28

thoracic cage

Answer 28

surrounds thoracic cavity
semi rigid: can widen to accommodate expansion of lungs
- composed of thoracic vertebrae, sternum, ribs and costal cartilage
12 pairs of ribs

Question 29

explain how the ribs are categorized based on structure

Answer 29

7 true ribs: vertebrosternal ribs attach to sternum via costal cartilage
5 false ribs = don’t directly attach to sternum
- 3 vertebrochondral ribs connect to cartilage of rib 7
- 2 floating ribs only attach at vertebrae