1. Thorax Osteology

2. Contents
Overview
Sternum
Ribs
Clavicle
Thoracic Vertebrae

3. Overview Thorax is region of body contained within ribcage
bony thoracic wall, the sternum helps protect the internal thoracic viscera – such as the heart, lungs and oesophagus

4. Overview Superior thoracic aperture Manubrium Ribs 1
Body of T1 vertebrae
Inferior thoracic aperture
Costal margin
Ribs 11 and 12
Xiphoid Process
Body of T12 vertebrae

5. Sternum
Split into 3 parts

6. Sternum Manubrium Trapezoid shape, superior to sternum
Articulation point for:
Clavicle
Rib 1
Half of rib 2
Jugular notch (T2)
Sternal angle (T4/5)
- These fossae articulate with the medial ends of the clavicles, forming the sternoclavicular joints.
- On the lateral edges of the manubrium, there is a facet (cartilage lined depression in the bone), for articulation with the costal cartilage of the 1st rib, and a demifacet (half-facet) for articulation with part of the costal cartilage of the 2nd rib.
- The sternal angle is commonly used as an aid to count ribs, as it marks the level of the 2nd costal cartilage and same level as aortic arch and carina (bifurication of trachea)

7. Sternum Body ‘’Chest Bone’’
Articulation with costal cartilages of ribs 3-6
The lateral edges of the body are marked by numerous articular facets (cartilage lined depressions in the bone). These articular facets articulate with the costal cartilages of ribs 3-6. There are smaller facets for articulation with parts of the second and seventh ribs – known as demifacets

8. Sternum Xiphoid Process
Inferior to the body of sternum
Found at T10
Marks central tendon of diaphragm, inferior border of heart and superior border of liver
The xiphoid process is largely cartilaginous in structure, and completely ossifies late in life – around the age of 40
Xiphesternal joint at T9

9. Ribs Form the protective cage of the thorax 12 ribs
Typical or atypical
True, false or floating
As part of the bony thorax, the ribs protect the internal thoracic organs. They also have a role in breathing – during chest expansion the ribcage moves to permit lung inflation
Atypical – features not typical with other rribs

10. Ribs True Ribs 1-7 (attach to sternum via costal cartilage) False Ribs
8-10 (attach indirectly to sternum via costal cartilage of superior rib)
Floating Ribs
11 & 12 (not attached to sternum)

11. Typical Ribs Ribs 3-9 Consists of head, neck and body Tubercle Angle
Costal Groove
Angle
Crest
- One facet articulates with the numerically corresponding vertebrae, and the other articulates with the vertebrae above
- groove for the neurovascular supply of the thorax, protecting the vessels and nerves from damage
- The smooth part of the tubercle is the articulates with transverse process of corresponding vertebrae.
- The rough part of the tubercle is for attachment of the costotransverse ligament.
- Costochondral joint attaches the rib to the costal cartilages.

13. Atypical Ribs Rib 1 Shorter Only one articular facet (T1)
Grooves for SCA/SCV
Tubercle for anterior scalene
Rib 2
Thinner and longer than rib 1
Rough surface where posterior scalene attaches

14. Atypical Ribs
Rib 10
Only one facet on head
Rib 11 & 12
No neck

15. Clavicle ‘’Collar Bone’’ ‘S’ shaped Extends from manubrium to scapula
2 ends – acromial and sterna
Midclavicular line
Forms part of pectoral girdle
Subclavian groove for attachment of subclavius muscle
Attach the upper limb to the trunk
Transmits forces from the limb to the axial skeleton
The pectoral girdle is made of the clavicle and the scapula. It helps fix and hold the 1st rib in place so that the rest of the rib cage can expand and compress when taking a breath.

16. Thoracic Vertebrae 12 thoracic vertebrae forming thoracic spine
Heart shaped
Circular vertebral foramen
L-P rule:
Lamina are Posterior
Pedicles are Lateral
Laminae form the posterior walls of the vertebral foramen and connect the transverse process to spinous process.
Pedicles form the lateral walls of the vertebral foramen and connect the body to the transverse process.

17. Thoracic Vertebrae 12 thoracic vertebrae forming thoracic spine
Heart shaped
Circular vertebral foramen
L-P rule:
Lamina are Posterior
Pedicles are Lateral
Ribs articulate with same level TV but also with superior one too
Bilateral facets for ribs characteristic of thoracic
Costal facets on T1-10 only

18. Clinical Relevance Flail Chest
Rib breaks in two places
Causes detachment from chest
Prevents proper ventilation
During inhalation, broken rib moves inwards
Prevents proper ventilation thus oxygenation of blood
Vice versa

19. Quiz What is the arrow pointing to? Xiphoid process
What vertebral level does it sit?
T10
What articulates with the manubrium?
Clavicle, and costal cartilage of Rib 1 & 2

20. Summary
Had a look into the bones that make up the thorax – Sternum, ribs, clavicle and thoracic vertebra
Also looked at some clinical relevance towards the osteology of the thorax