The Thoracic Cavity Flashcards
What level does the upper limit of the heart reach?
3rd costal cartilage of right hand side and 2nd costal cartilage on left hand side
What levels does the right margin of the heart extent from and to?
3rd costal cartilage to 6th costal cartilage on right hand side
What level does the lower limit of the heart reach?
6th costal cartilage on right hand side to apex in 5th intercostal space near midclavicular line
What 2 vessels pass over the first rib?
- Subclavian vein
2. Subclavian artery
Explain the mechanism of inspiration
· Increased volume of pleural cavities
· Lowered pressure
· Higher atmospheric pressure
· Lungs fill with air
How does the mechanism of quiet inspiration work
· Scalene muscle contracts to fix first rib
· Contraction of external intercostal muscles causes ribs drawn together and raise up
· Sternum moves out
· Diaphragm contracts and moves down
What is the main difference between quiet and forced inspiration?
Every muscle is brought into play, including scalenus anterior and medius and sternocleidomastoid
What occurs when scalenus anterior and medius contract during forced inspiration?
First rib is raised
What occurs when sternocleidomastoid contracts during forced inspiration?
Sternum and clavicle are raised
What word best describes normal expiration?
Passive
What occurs during normal expiration?
Respiration muscles relax and elastic recoil forces air out of the lungs
What is the main difference between normal and forced expiration?
Abdominal muscles contract in forced expiration to raise pressure so forcefully expel air from the lungs
What muscle fixes the 12th rib during forced expiration?
Quadratus lumborum
What are lungs surrounded in?
Pleura fluid
What are the two layers of pleura fluid which surrounds the lungs?
- Parietal pleura
2. Visceral pleura
