Lecture 16 Flashcards
What is included in the thoracic cavity?
Mediastinum: heart, vessels, pericardium
Pleural cavities: Lungs
What are the boundaries of the thoracic cavity?
Anterior: sternum Posterior: Thoracic Vertebrae Lateral: Ribs Superior: base of neck Inferior: diaphragm
What happens if there is damage in the thoracic cavity?
the whole system will shut down
Role of the Hilum?
Allows things toi enter
Layers of the Pleural cavity?
Parietal pleura
Visceral pleura
How is ventilation driven by pressure changes in thoracic cavity?
- Pressure is inversely proportional to volume.
- breathe in (volume increases)
- breathe out (volume decreases)
What is Boyle’s Law
P = 1/V
Pressure inversely proportional to volume
- measured by collisions
Air will move to lower pressure space.
Why is a pressure gradient important?
For us to breath air needs to move which requires a gradient. Between breaths there is no gradient because pressure inside cavity = pressure outside
What are Anterior thoracic joints?
Areas of costal cartilage (hyaline) that can be synovial or cartilaginous and connects sternum to ribs.
Sternocostal joints?
where they articulate
Synovial (except 1st which is cartilaginous
Costochondral?
ribs-cartilage joint
Cartilaginous
Interchondral?
don’t attach directly only to the cartilage
Synovial
What are posterior thoracic joints?
Articulations between thoracic vertebrae and ribs
Synovial joints
Costotransverse?
Between rib and transverse process of vertebrae
Costovertebral?
Between rib and body of vertebrae
Role of respiratory muscles?
they move the ribcage allowing us to breathe
What are the primary inspiratory muscles?
Diaphragm and intercostals
What are accessory muscles?
Active only when needed
Structure of the diaphragm?
Sheet of skeletal muscle.
Dome shaped when relaxed and flattened when contracted.
Function of diaphragm?
Separates thorax from abdomen.
Contraction expands thoracic cavity, compresses abdominopelvic cavity.
Structure of Intercostal muscles?
Attach diagonally between neighbouring ribs. Internal and external…Internals lie in opposite direction to externals
Function of external intercostals?
Lift ribcage and expands cavity.
Inspiration - quiet and forced
Internal intercostals?
Depress ribcage and decrease cavity.
Expiration forced only.
Difference between Forced and quiet breathing?
Forced = drawing more air in (talking), quiet = normal breathing
What is thr role of accessory muscles?
Involved in forced breathing… some increase volume of cavity and other decrease volume.
What muscles are involved in inspiration?
During quiet breathing the diaphragm contracts and flattens and External intercostals contract which lifts the ribs.
During forced breathing the same occurs but accessory muscles contract further to. expand thoracic cavity.
What muscles are involved in expiration?
During quiet expiration the diaphragm relaxes making a dome shape and external intercostals relax so that ribs are not longer lifted.
During forced expiration the same occurs but internal intercostals lso contract to depress the ribs and accessory muscles contract to further decrease cavity volume.
How do lungs expand as the cavity does?
Lung tissue is elastic and always trying to recoil.
The pleura make the lungs stick to the thoracic wall.
Expand during inspiration and decrease during expiration.
Name the different pleura
Visceral pleura on lungs
Parietal pleura on thoracic cavity.
Where is pleural fluid found?
Slippery surfaces for frictionless movement against other structures.
What causes lungs to stick to the thoracic wall.
