Axial skeleton

Question 1

What is the axial skeleton?

Answer 1

Bones of skull, vertebral column, ribs, sternum

Question 2

What is the skull?

Answer 2

A rigid bony box that protects the brain and special sense organs

Question 3

What is the skull composed of?

Answer 3

Calvaria, facial bones (temporal, occipital, frontal and maxilla)
Overall 22 bones

Question 4

What is the calvaria?

Answer 4

Upper domelike portion of the bony skull

Question 5

What is the calvaria composed of?

Answer 5

Flat bones that articulate at Sagittal, coronal and lambdoid sutures via synarthroses (fibrous) joints

Question 6

What is the vertebral column?

Answer 6

Bones that make up the spine

Question 7

What bones make up the vertebral column?

Answer 7

Cervical - 7
Thoracic - 12
Lumbar - 5
Sacrum - 5
Coccyx - 4 fused

Question 8

What lies between the vertebrae? What joint does it form? What is the function of this?

Answer 8

Intervertebral discs
Forms fibrocartilaginous joint
Allows slight movement of vertebrae, acts as a ligament holding vertebrae

Question 9

What is the thoracic cage?

Answer 9

Skeleton of thoracic wall

Formed by thoracic vertebrae, ribs and sternum

Question 10

Function of the thoracic cage

Answer 10

Surrounds thoracic cavity protecting the heart and lungs, supports pectoral (shoulder) girdle

Question 11

What is the sternum?

Answer 11

Flat bone that forms the medial and anterior part of thorax

Question 12

Parts of the sternum

Answer 12

Manubrium, sternum, xiphisternum (xiphoid process)

Question 13

What is the sternal angle?

Answer 13

Important landmark

Question 14

Joint between manubrium and body

What vertebral level is this at?

Answer 14

Manubriosternal joint at t4/5

Question 15

Functions of the sternum

Answer 15

Protects internal thoracic vertebrae eg heart, lungs

Question 16

Bony landmarks and articulations of manubrium

Answer 16

Superior - depression called jugular notch, either side of notch is large fossa lined with cartilage. These articulate with medial end of clavicle forming sternoclavicular joint

Lateral - facet for articulation with costal cartilage of the 1st rib, demifacet for articulation with part of costal cartilage of 2nd rib

Inferior - manubrium articulates with body of sternum forming sternal angle, commonly used as an aid to count ribs as it marks the level of 2nd costal cartilage

Question 17

Bony landmarks and articulations of the body of sternum

Answer 17

Superior - articulates with manubrium (manubriosternal joint)

Lateral - numerous facets for articulation with costal cartilages of ribs 3-6, demifacet for articulation with parts of rib 2 and 7

Inferior - articulate with xiphoid process forming xiphisternal joint

Question 18

Features, bony landmarks and articulations of xiphisternum

Answer 18

Level of t10, largely cartilaginous, ossifies at ~40 years

In some people, it articulates with part of costal cartilage of 7th rib

Superior is xiphisternal joint

Question 35

What are the ribs?

Answer 35

Set of 12 bones which form the protective cage of the thorax

Question 36

Function of ribs

Answer 36

Protect internal thoracic organs

Role in breathing - during chest expansion the rib cage moves to permit lung inflation

Question 37

Articulations of the ribs

Answer 37

Posterior :
All 12 rubs articulate posteriorly with vertebrae of spine. 2 joints:
Costotransverse - between tubercle of ribs and transverse costal facet of corresponding vertebrae
Costovertebral - between head of rib, superior costal facet of corresponding vertebrae and inferior costal facet of vertebrae above

Anterior:
1-7 attach independently to sternum
8-10 attach to costal cartilage superior to them
11 and 12 do not have anterior attachment and end in abdominal musculature = floating ribs

Question 39

Where is the most common site for rib fractures?
What causes ribs to fracture?
Common complication?
Organs most at risk of damage

Answer 39

Commonly occur in middle ribs
Consequence of crushing injuries
Common complication is further soft tissue injury from broken fragments
Structures most at risk are the lungs, spleen or diaphragm

Question 40

Classifications of ribs and their anatomical features

Answer 40

Typical:
Head - 2 articular facets, one facet articulates with the numerically corresponding vertebrae and the other with the vertebrae above
Neck - simply connects head with body, roughed tubercle with a facet for articulation with transverse process of corresponding vertebrae
Shaft - flat and curved, internal surface has a costal groove for intercostal vein, artery and nerve

Atypical:
Rib 1 - shorter and wider, one facet on head for articulation with corresponding vertebrae, superior surface marked by two grooves for subclavian vessels
2 - thunder and longer, 2 articular facets on head, roughened area superior surface where serratus anterior muscle attaches
10 - one facet for articulation with its numerically corresponding vertebrae
11 and 12 - no neck, one facet for articulation with corresponding vertebrae