The Thoracic Cavity Flashcards
What forms the bony thorax
Sternum
Ribs
Thoracic vertebrae
Costovertebral joints
Rib movement
What does the sternum consist of
What features can be found on the ribs
Two articular facets on the head
One articular facet on the tubercle
Costal groove on the inferior aspect of the shaft
What are the types of intercostal muscles
External
Internal
Innermost
Describe the structure and function of the external intercostal muscles
Fibres run anteroinferiorly from rib above onto rib below
30% of chest expansion during quiet respiration - elevates ribs in bucket handle movement
Describe the structure and function of the internal and innermost intercostal muscles
Fibres run inferoposterioly from rib above onto rib below
Pull ribs down from position of chest expansion
Only during forceful expiration
What is the function of the diaphragm - describe its movement
70% of chest expansion during quiet respiration
Diaphragm moves down on contraction - moves down 2 ICSs
What nerve innervates the diaphragm
Phrenic nerve (C3-5)
Where are the openings on the diaphragm and what does it open for
T8 for IVC
T10 for oesophagus
T12 for abdominal aotra
Where is the diaphragm positioned - ICS position
Lies at the level of the 4th ICS on the right
Lies at the level of the 5th ICS on the left
Name two accessory muscles and how they function to aid breathing
Pectoralis - changes origin to be humerus so it can pull on the thorax to aid intercostal muscles
SCM - lifts ribs to increase ventilation. Will appear strained
Describe the neurovasculature of the thorax
Intercostal arteries, veins and nerves run in the costal grooves of ribs
Collateral branches run on the upper surface of ribs
Internal thoracic artery and vein supply the sternum and some intercostal muscle parts
Azygos system drains blood from ICSs
