Anatomy and Ventilation Flashcards
Can we palpate the first rib?
No
What part of the anatomy allows us to do chest compressions?
Costal cartilages (allow some give)
How many ribs on each side of direct connections to the sternum?
7 ribs
How many ‘false’ ribs do we have on each side?
3
How many floating ribs are there on each side?
2 (ribs 11 and 12)
How far does the diaphragm move in breathing?
Can move one and a half intercostal spaces
Describe the diaphragm
Fibromuscular membrane separating the abdomen from the thorax
Neurovascular structures pass through the central part
The heart sits on the central tendon of the diaphragm
Describe the external intercostal muscles
Fibres run in the direction of putting hands in pockets
Same direction as external obliques in abdomen
Pull the ribs up when they contract
(First rib is tethered by other muscles therefore acts as an anchor point)
Describe the internal intercostals
Fibres run perpendicular to external intercostals
Pull the ribs down on contraction
Describe the innermost intercostal
Thin, weak, hard to see
Mostly found laterally on the thorax
Fibres run parallel to internal intercostals therefore actions are the same - pull ribs down on contraction
Exercise increases the amount of intercostals you need
Where do the structures cross the diaphragm?
Vena cava = T8
Oesophagus = T10
Aorta = T12 (aortic hiatus)
Where are the neurovascular bundles in the ICSs?
Thick bundles at the top of ICS
Therefore insert needles into the bottom of ICS
What do the thick bundles in the ICSs usually contain?
Posterior intercostal artery
Posterior intercostal vein
Intercostal nerve
Describe the venous drainage of the thoracic cavity
Posterior of thoracic cavity we have the azygous venous system
Main azygous vein found to right of vertebral bodies
Collects blood from ICSs via hemiazygous and accessory hemiazygous veins
Drains into SVC
Describe the phrenic nerves
C3, 4 and 5
Control the diaphragm
Motor nerves but also sensory (caused of referred pain)
Run anterior to hilum of the heart
Foreign bodies tend to go in which direction when inhaled and why?
Right lung
Right main bronchus is at a much less acute angle than the left main bronchus
What provides the dual blood supply to the lungs?
Pulmonary arteries
Bronchial arteries
How does the diaphragm move in ventilation?
Contracts (moves down) in inspiration
Relaxes in expiration
Describe the process for how the air enters the lungs
Inspiratory muscles contract
Thoracic cavity expands
Pleural pressure becomes more negative
Lungs inflate
Alveolar pressure becomes subatmospheric
Air flows into the lungs until they equal atmospheric pressure
If everything wasn’t stuck together well, where would the lungs, thoracic cage and diaphragm move?
Lungs - in and up
Thoracic cage - out
Diaphragm - down
What are the stages of the respiratory cycle?
- Inspiration
- Rest
- Expiration
- Pause
What is the average tidal volume?
0.5L (500ml)
The intrapleural pressure is always …
Negative
What is the average air flow?
1 litre per second (decreases with age)
Describe forced expiration
Beyond the resting expiratory level
Use of the abdominal muscles and the internal intercostal
Occurs during exercise, respiratory obstruction and some disease states
Define the residual volume
Amount of air that can never be expelled from the lungs
What percentage of the oxygen you breathe in each breath gets to the alveoli?
20%
Define the inspiratory capacity
Inspiratory reserve volume + tidal volume
Give some reasons why the diaphragm may not be able to move into the abdomen as easily
Pregnancy
Obesity (fat is not compressible)
Corsets
Which muscles are used in forced inspiration?
Diaphragm External intercostals Sternocleidomastoid Scalene Serratus anterior Pectoralis major
What muscles are used in forced expiration?
Internal intercostals
External oblique
Internal oblique
Rectus abdominus
