2.2 diaphragm and mechanisms of breathing Flashcards
what is the attachment between thoracic cage and diaphragm?
fibres on bottom of thoracic cage project superiorly and attach to the central tendon
what are the three types of arcuate ligaments projecting from the diaphragm?
median arcuate ligament
medial arcuate ligament
lateral arcuate ligament
what is the purpose of the median arcuate ligament?
attaches to vertebral bodies
what is the purpose of the medial and lateral arcuate ligament?
because the psoas major and quadratum lumborum are in front of the posterior thoracic cage, the arcuate ligaments attach to those muscles instead
what is the purpose of the median arcuate ligament
attaches diaphragm to vertebral bodies
where do the crura of the diaphragm attach to the vertebral body?
left crus: L1-L3/4
right crus: L1-L2/3
what is the purpose of the crura?
anchor the diaphragm posteriorly around the aorta
how does diaphragmatic movement affect central tendon?
diaphragm contracts, pulls central tendon down, depresses diaphragm
what are the 3 structures that pierce the diaphragm?
IVC - T8
oesophagus - T10
aorta - T12
what happens to the IVC during inspiration?
- diaphragm depresses
- stretches central tendon and IVC
- intraabdominal pressure increases
- blood rushes through IVC towards thorax
why can’t swallowing and inspiration occur at the same time?
when diaphragm contracts, pulls crura sling around oesophagus
what type of sphincter does the crura act as around the oesophagus
functional sphincter
what nerve innervates the diaphragm, performing motor function?
phrenic nerve
how does the sympathetic trunk pass through the diaphragm?
runs lateral to the crura and through the medial arcuate ligament
what dermatomes is pain from the central diaphragm referred to?
C3, C4, C5 from phrenic nerve
where is pain from the peripheral diaphragm referred to?
dermatomes of the thoracic wall
what innervates the peripheral diaphragm
lower intercostal nerves
how does the phrenic nerve (L and R) descend and access the diaphragm?
- passes anteriorly to root of lung
- descends through thorax
what parts of the thorax does the phrenic nerve supply?
- motor to all diaphragm
- sensory to central diaphragm
- sensory to pericardium
how does air move into lungs?
air moves from high pressure to low pressure to equalise the pressure gradient
what happens during inspiration (in terms of volume and pressure?)
- increases volume
- decreases pressure
- atmospheric pressure is greater than lung pressure
what happens during expiration (in terms of volume and pressure?)
- decreases volume
- increases pressure
- lung pressure is greater than atmospheric pressure
how does the relationship between the visceral and parietal pleura affect lung movement?
- parietal pleura firmly attached to thoracic cage and diaphragm
- visceral pleura on surface of lungs
- the surface tension between these two layers and the fluid inside the pleural cavity pulls the lungs to expand when the thoracic cage expands
what muscle controls quiet breathing, and how does it perform this function (or what controls its contractions)?
diaphragm. rhythmic contractions are controlled by the respiratory centre of the brainstem
explain the pump handle movement of the ribs
elevation of upper ribs (2-6) result in movement forward of sternum because of attachments to sternum
explain the bucket action
elevation of lower ribs pulls ribs laterally outwards
