Bones

Question 1

Features of Thoracic Cage

Answer 1

> 12 vertebrae (Kyphotic curve)
> 12 ribs (7 true, 5 false - 2 floating)
> Intercostal spaces 
> Costal cartilages 
> Sternum

Question 2

Function of thoracic cage

Answer 2

> Protect vital organs
Provide muscle attachment
Assists respiration

Question 3

Typical Thoracic vertebrae

Answer 3

> Round body (increasing in size as we descend) with 2 costal demi-facets
Pedicles connect body + arch
Articular facets are more vertically inclined (moving from horizontally sloped in cervical to wrapped in lumbar)
Transverse processes project laterally with facets for the relevant rib
Laminae connect the spinous and transverse processes
Long, slanted spinous process which projects posteriorly and inferiorly

Question 4

Spinous processes - rule of 3

Answer 4

> T1-3: SP is at level of TP (TP is slightly above)
> T4-6: SP is 1/2 level below TP
> T7-9: SP is 1 level below TP
> T10: SP is 1 level below TP
> T11: SP is 1/2 level below TP 
> T12: SP is at level of TP

Question 5

Atypical vertebrae

Answer 5

> T1: single facet on body for articulation with own rib
T10: No inferior demi-facet (Rib 11 is floating)
T11: single facet on body for own rib
: No costal facet on transverse process
T12: Single facet on own body for own rib
: No costal facet on transverse process

Question 6

Ribs

Answer 6

> Upper 7 ribs = True ribs - articulate directly with sternum via own costal cartilage
Lower 5 ribs = False ribs - Don’t directly articulate with sternum
+ Ribs 11 + 12 = Floating ribs - no costal cartilage (free end) + no articulation with transverse process
Costal cartilages = relatively mobile
- connect anterior rib to sternum

Question 7

Typical Ribs

Answer 7

> Ribs 3-9
Head - 2 demi-facets for articulation with vertebra above + at level (crest between facets which has a ligament that connects to the intervertebral disc)
Neck
Tubercle - with articular area (to transverse process of same level) and non-articular area
Angle - changes direction to wrap round thorax
Shaft
Costochondral junction - where rib meets costal cartilage = Primary Cartilaginous joint = Synchondrosis

Question 8

Atypical Ribs

Answer 8

> 1: Shorter and wider 
    : one facet on it's head for T1
    : Superior surface has grooves on surface for subclavian vessels and scalene attachment (between which the brachial plexus exits)
> 2: Twice as long as rib 1
      : 2 facets on its head
> 10 : single facet for T10
> 11+12: single facet + no neck

Question 9

Sternum

Answer 9

> Manubrium (facet for clavicle and rib 1 + demi-facet for rib 2)
- angle of louis - manubriosternal joint = symphysis that will ossify with age but has some movement to aid respiration
-
Body (demi-facet for rib 2, facets for ribs 3-6, demi-facet for rib 7)
(xiphisternal joint - symphysis that ossifies with age)
Xiphoid process - demi-facet for rib 7