Lecure 14: Diaphragm

Question 0

Congenital diaphragmatic hernia

Answer 0

Incidence in WA (1991-2002): 3.8 cases/ 10 000 live births
-only 52% of live born infants with CDH survived to one year old
Slide 5
-basically a hole in the diaphragm which the intestines protrude through.

Question 1

Embryonic development

Answer 1

-Develops during weeks 4-12
-4 structures come together to form the diaphragm
-septum transversum folds underneath developing heart and picks up venal rami of spinal nerves C3-C5
By 8 weeks it descends to thoracic level
Slide 3

Question 2

Normal infant development

Answer 2

Birth: at birth diaphragm is in oblique position.
By 4-months old: the erect posture of kid and stabilising activity of abdominal muscles pull diaphragm into horizontal position :)

Question 3

Diaphragm

Origin, insertion, action, innervation?

Answer 3

Had right dome higher than left due to liver pushing up.
Musculotendinous partition separating thoracic and abdominal cavities.
Chief muscle of inspiration. When it contracts dome flattenes
Dome shaped
Right dome is higher why?
Origin: thoracic outlet: xiphoid process, costal cartilages of ribs 6-12, L1-3
Insertion: converge into central tendon
Motor innervation: left and right phrenic nerves (C3, C4, C5) -keep the diaphragm alive!
Sensory innervation: centre= phrenic nerve, periphery = intercostal nerves T6-T12
Action: draws central tendon down and forward during inspiration

Question 4

Learn image on page 13 of diaphragm

Answer 4

The muscle is out on the periphery. There is a bare area were the pericardial sac sits
3 openings for oesophagus, IVC, and thoracic aorta.
Central tendon in the middle

Question 5

Left and right crus. What do they do?

Answer 5

They Anchor the diaphragm to lumbar vertebrae
Blend with anterior longitudinal ligament of vertebral column,
Right crus: larger and longer, arises from sides of L1-L3 vertebral bodies and IV discs
Left crus: arises from sides of L1-L2 and IV discs
Slide 14

Question 6

Arcuate ligaments. Tell me each and what they do

Answer 6

Median accurate ligament: connects left and right crura
Medial accurate ligament: thickening of fascia covering psoas major muscle
Lateral accurate ligament: thickening of fascia covering quadratus lumborum muscle.
Helping attach the posterior aspect of the diaphragm.

Question 7

Diaphragmatic apertures. We need to get stuff going from the thorax into the abdomen. They have 3 openings which they can go through or squish down the sides.

Answer 7

We have:
T8: most anterior (caval) opening
T10: esophageal opening
T12: aortic opening were aorta pops out left and right crus.
Which is the most susceptible to weakening/ widening?
Esophageal hiatus is penetrating right crus and because aortic has medial arcuate ligament.
Can end up with a hiatal hernia

Question 8

What are the major structures transversing the diaphragm?

Answer 8

What level what traverses it?
T8: caval opening, most superior. Right phrenic nerve also passes through
T10: oesophageal hiatus- oesophagus, right and left vagus nerves
T12: aortic hiatus: posterior to diaphragm but anterior to vertebral column
-aortas thoracic duct, azygos vein
Understand not memorise

Question 9

What are the structure that pass around the diaphragm instead of through?

Answer 9

• greater and less splanchnic nerves (pass through crura on each side)
• hemiazygos vein (passes through left crus)
• least splanchnic nerve and sympathetic trunk (passes posterior to medial arcuate ligament.
• superior epigastric vessels (anterior to diaphragm, just deep to ribs

Question 10

What is a hiatal hernia

Answer 10

Is when we get widening of that right crus, looses slack. So stomach protrudes into the thoracic cavity
-affects 10-50% of population

Question 11

What is the position of the diaphragm during expiration and inspiration

Answer 11

Expiration:

• right dome reaches as high as 5th rib (just under nipple)
• left dome reaches as high as the 5th intercostal space

Inspiration:
-central tendon moved inferiorly and domes “flatten out”

Question 12

Inspiration. What’s diaphragm do?

Answer 12

Caval opening is attached to the central tendon so when the diaphragm contracts it puls open. So it dilates the IVC, which increases venous return.

Question 13

Tell me about referred pain

Answer 13

Because we have 2 different sensory innervation. We have 2 different sites of referral, so pain in the central region of the diaphragm travels back along the visceral afferent fibres of the phrenic nerve and therefore is referred to skin of dermatome of C3, C4, C5 so skin of the supraclavicula region.

Pain from the periphery of the diaphragm will travel along visceral afferent fibres of intercostal nerve and be referred to the skin over the costal margins of anterolateral abdominal wall.

Question 14

Blood supply

Answer 14

Right pericardiophrenic artery and vein (centre)
Right musculophrenic artery and vein (outside)
Slide 24

Right inferior phrenic vein and arty
Left inferior phrenic vein

Question 15

Treatment of lung tuberculosis, they section some of the phrenic nerve

Answer 15

To rest the lower lobes of the lung because every time diaphragm contracts it bumps lower lobe.

Question 16

What is the valsalva manoeuvre

Answer 16

It was used in 17th centry to expel pus from the middle ear.

• forced expiration with a closed glottis and abdominal contraction ie equalising when diving, weight lifting
• your increasing your interthrasic pressure because your blocking air from escaping because your closing your glottis. So increasing intra thoracic pressure therefore traps blood in great veins reducing venous return, so when breath is release massive increase in blood flow, pressure and HR, which stimulates reflex bradycardia so it drops heart rate and blood pressure

Question 17

Synchronous diaphragmatic flutter (hiccups)

Answer 17

Sudden contraction of diaphragm and closure of glottis pulls air rapidly through larynx causing a hic sound.

• relax arc (Vagal afferents; phrenic and intercostal efferents)
• good for babies to strengthen diaphragm.m