Thorax Flashcards
What types of joints are the sterno-manubrial and costo-sternal joints?
These are cartilagenous joints.
However after the age of 40 the sterno-manubrium and sterno-xiphoid joints can become ossified
What are the names of the different ribs
True ribs - 1-7. These have direct attachments to the sternum through cartilage
False ribs - 8-10. Don’t directly articulate with the sternum. Instead their cartilage join together and THEN join with the cartialge of the 7th rib
Floating ribs - 11 and 12 don’t articulate with the sternum at all
How does pectus excavatus come about?
Failure of fusion of the twin fetal sternal bars.
Which rib forms the subcostal margin?
The 10th rib.
The two floating ribs finish too posteriorly to be palpated in the mid axillary line.
Which rib is in line with the lower border of the scapula?
The 7th rib
How do the true and false ribs differ in terms of their movements in relation to increasing intrathoracic volume?
True ribs (Except rib 1) - have a pump handle effect. They Increase the anterio-posterior diameter of the thoracic cage
False ribs - 8-10. have a bucket handle effect. Increase the transverse diameter of the thoracic cage.
Where does the diaphragm originate fetally?
It originates high cervically. The structure known as the septum transversum.
This explains the relatively long route of the phrenic nerve (C3-5)
Which accessory muscles become incoorporated during respiratory distress?
Sternocloidomastoid - Pulls the clavicle up and increases the thoracic volume
Pectoralis major - has attachments on the sternal portion of the clavicle, cartilagenous portions of the true ribs and abdominal aponeurosis. Pulls the thorax anteriorly to provide more volume
Why do late - term pregnant women have increased anterio-posterior chest wall movement during respiration at rest?
The large uterus splints the diaphragm. This prevents much downward movement of the diaphragm when it contracts. So thoracic expansion is achieved through intercostal muscle action.
