Lungs and Pleural Cavity Flashcards
What is pleura?
Where does the pleura reflect?
Pleura is the serous membrane that lines the interior walls of the thoracic cavity and the surface of the lungs
The pleura reflects at the lung roots
What is the pleural cavity?
What does it contain?
Why is it called a potential space?
The pleural cavity is the vacuum pleural-fluid filled space between the parietal pleura and visceral pleura surrounding the lungs. Normally the two pleura are attached together by the surface tension of the pleural fluid - so the pleural cavity is called a potential space.
What is the function of pleural fluid?
- Lubricant: Pleural fluid allows the visceral and parietal pleura to slide against each other
- Surface Tension: The surface tension of pleural fluid causes the visceral pleura to stick to the parietal pleura and lifts the lungs causing it to expand when the chest wall expands during inhalation
What is the exceptional area of the pleural cavity?
What happens here?
The costodiaphragmatic recess is an exceptional area where the two pleura do not stick together. There is a space between the visceral pleura and the parietal pleura.
It is referred to as the most dependent part (lowest part) of the pleural cavity since it is where abnormal fluid collects in a standing patient: seen by fuzziness in a radiograph
Label the diagram
Why does the left lung not have a middle lobe?
What does it have instead?
There are many explanations – one of which is that the heart is positioned on the left so takes up that space.
Instead the left lung has a lingula of the superior lobe
What is the root of the lung called?
What structures does it contain?
Hilum
Contains
- main bronchus
- pulmonary artery
- pulmonary veins x(2)
Smaller structures:
- nerves
- pulmonary lymph nodes
Label the diagram
What is the order of the structures at the root of the lung?
What great vessels impress upon the lung in this diagram? (which lung)
The ORDER of structures at the hilum
- Most posteriorly = airway, the primary bronchus
- Most superiorly = pulmonary arteries
- Most anteriorly and inferiorly = pulmonary veins
Label the diagram
What is the order of the structures at the root of the lung?
What great vessels impress upon the lung in this diagram? (which lung)
The ORDER of structures at the hilum
- Most posteriorly = airway, the primary bronchus
- Most superiorly = pulmonary arteries
- Most anteriorly and inferiorly = pulmonary veins
Label the nerve in the diagram
What is its name?
Where does it originate from?
Where is it found (across 2 parts of the body)
What is its function?
Phrenic Nerve
The combined anterior rami of cervical spinal nerves C3, 4, 5
Found in the neck on the anterior surface of scalenus anterior muscle
Found in the chest (thorax) descending over the lateral aspects of the heart (the yellow nerves in the picture)
Supply motor and sensory fibres to the skeletal muscle of the diaphragm: C3, 4 and 5 keep the diaphragm alive
Describe the mechanics of inspiration
-
Diaphragm contracts and descends
* Increases verticalchest dimension -
Intercostal muscles contract elevating ribs
* Increases A-P and lateral chest dimensions - The chest walls (pleura) pull the lungs outwards with them
* Negative pressure: Air flows into the lungs
Describe the mechanics of expiration
- Diaphragm relaxes and rises
* Decreases vertical thoracic dimension - Intercostal muscles relax lowering ribs
* Decreases A-P and lateral chest dimensions - Elastic tissue of lungs recoils
* Air flows out of lungs: tissue recoil pushes air out of lungs
What are the normal muscles of respiration?
When are the accessory muscles of respiration recruited?
What are the accessory muscles of respiration (expiration and inspiration)?
Normal muscles of breathing:
- diaphragm and
- intercostal muscles
Accessory muscles recruited when we are struggling to breathe:
- Exercise
- High altitude
- Asthma
People lean after marathon to fix the accessory muscles that attach to the thoracic cage so they are no longer involved in moving the arms/keeping us upright, but can be recruited for breathing
Accessory muscles can be any muscle attached to the thoracic cage
Forced Inspiration:
- Pec major
- Pec minor
- Scalene muscle
- Sternocleidomastoid
Forced Expiration:
- Rectus Abdominus: used to compress abdominal contents. diaphragm actively pushed back up into its resting position by the compressed abdominal contents
What is pneumothorax?
What does it result in?
How can it be caused?
Pneumothorax: Air in the pleural cavity
- Vacuum lost and lung collapses due to elastic recoil
Causes
- Injury to chest wall: allows air entry into pleural cavity via tear in parietal pleura
- Lung tissue may rupture: causing release of air into the pleural cavity via tear in visceral pleura
In both cases vacuum lost and lung collapses due to elastic recoil
Describe the bronchial tree
The bronchial tree:
- Trachea bifurcates at the level of the sternal angle in the right and left main bronchus
- Main bronchi split into lobar bronchi (1 per lobe)
- Lobar bronchi split into 10 broncho pulmonary segments
- Broncho pulmonary segments supplied by segmental bronchi
