T10 level, though the right crus (acts like a sphincter because of muscle fibres) Oesophagus Both vagus nerves Left gastric vessels

T12, behind the median arcuate ligament Aorta • thoracic duct Azygos Hemiazygos

Diaphragm Flashcards by Orla Mcdonnell

What is the diaphragm?

Thin, musculotendinous
Muscular at its periphery, tendinous centrally
closes the inferior thoracic aperture

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Describe the shape of the diaphragm

Inverted J shape
Right hemidiaphragm is 1cm is higher than the left

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Describe the position of the diaphragm in full expiration

R= 4th intercostal
L = 5th intercostal

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What is the diaphragm attached to anteriorly?

Xiphoid process at vertebral level T8/T9
Deep surface of the last 6 ribs and costal cartilages

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What is the diaphragm attached to posteriorly?

• Lumbar vertebrae and intervertebral discs between them

left crus = L1-L2
right crus = L1-L3

• Median arcuate ligament

forms the aortic hiatus
medial borders of the crura

• Medial arcuate ligament

body - transverse process of L1

• Lateral arcuate ligament

Transverse process of L1 - rib 12

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What is the insertion of the diaphragm?

• Central tendon

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What level is the central tendon?

Xiphosternal synchondrosis

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What is a function of the central tendon

Fused to the pericardium
Halts the descent during forced inspiration
Further contraction of the diaphragmatic muscle pulls ribs 7-10 from the anchored central tendon

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What are the 3 openings of the diaphragm?

Caval opening
Oesophageal opening
Aortic hiatus

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Caval opening

T8, through the central tendon
Inferior vena cava
Right phrenic nerve

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Oesophageal opening

T10 level, though the right crus (acts like a sphincter because of muscle fibres)
Oesophagus
Both vagus nerves
Left gastric vessels

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Aortic hiatus

T12, behind the median arcuate ligament
Aorta • thoracic duct
Azygos
Hemiazygos

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What passes through the crura

Branches of the left phrenic nerve
Splanchnic nerves
Azygos
Hemiazygos

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What passes behind the medial arcuate ligament?

• Sympathetic trunk

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What is the vascular supply to the superior surface of the diaphragm?

Superior phrenic artery (branch of the thoracic aorta)
Branches of musculophrenic arteries
Branches of pericardiacophrenic arteries

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What is the vascular supply to the inferior surface of the diaphragm?

• Inferior phrenic artery - branch of the abdominal aorta

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What is the motor supply to the diaphragm?

Phrenic nerve
C3, 4!, 5

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What is the sensory supply to the diaphragm?

Phrenic: central tendon, parietal pleura and pericardium
Intercostal nerves: sensory from the periphery of the diaphragm (afferent)

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Where would you feel pain from the intercostal nerves?

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Where it is on the side
Does not refer pain

Describe the mechanism of inspiraiton

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Contraction flattens the dome of the diaphragm
Dome descends
Vertical diameter increases
Volume of the thorax increases
Intrathoracic pressure decreases
Air is drawn into the lungs

Describe the pump handle movement

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Body of the rib passes obliquely downwards: the anterior end of the rib is usually lower than the posterior end
Contraction of the external intercostals raise the body of the rib to the one above
This also lifts the sternum and pushes it anteriorly
Increases sagittal diameter, increasing the volume of the thorax

Describe the bucket handle movement

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Only occurs in ribs 8-10 - flat costo transverse joints that allow gliding
Once the central diaphragm is anchored, further muscle contraction pulls on the ribs and causes them to evert like a bucket handle

Accessory muscles

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Pectoralis major and minor (inspiration)
Lastissimus dorsi (inspiration and expiration)
fixate and stabilise ribs

• Abdominal wall muscles (expiration)

Which muscles help to fix the ribs?

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Neck and back muscles:

Trapezius
Sternocleidomastoid
Scalene muscles

Describe the boundaries of the pleura

* Rises to the level of the 1st rib, 2cm above the clavicle * 2nd CC - lies adjacent to the midline * 4th CC - LEFT - cardiac notch * 6th CC deviates laterally * 8th rib - mid clavicular line * 10th rib: mid axillary line * T12: midline (just below 12th rib)

Describe the boundaries of the lung

• Apex projects into the neck - curved line from the sternoclavicular joint to a point 2.5cm above the junction of the medial and intermediate thirds of the clavicle * 2nd CC: adjacent to the midline * 4th LCC: cardiac notch * 6th CC: deviates laterally * 6th rib: midclavicular line * 8th rib: mid axillary line * 10th rib: mid scapular line and mid line

Pleural recesses

* In quiet respiration, the lungs do not entirely fill the pleural cavities * This results in recesses which two layers of parietal pleura become opposed * Potential sites of accumulation of fluid from which they can be aspirated

Why is the intapleural pressure more negative?

* Surface tension between the parietal and visceral pleura pulls the visceral layer (and lung) with the movements of the thoracic wall * Elastic recoil of the lung tissue means the lungs are tending to deflate * This surface tension creates a slight negative pressure that maintains the lung in slight inflation even at the end of expiration

What is the costodiaphragmatic recess?

* Costophrenic recess * Narrow potential space between the periphery of the diaphragm and the ribs

Surface anatomy of the oblique lung fissure

* Curved line * Begins between spinous processes of T3 and T4 * Crosses the mid axillary line at the 5th intercostal space * Then follows the contour of the 6th rib

Surface anatomy of the horizontal lung fissure

* Follows the 4th intercostal space from the sternum * Until it meets the oblique fissure as it crosses rib 5

Where is the triangle of safety?

* Anterior border of latissimus dorsi * Lateral border of pectoralis major muscle * Horizontal level of the nipple (5th intercostal space) * Apex below the axilla * Can be used for fluid or air just depends on if you put catheter up or down

What is flail chest?

* Trauma resulting in fracture of the ribs and the sternum would cause a segment to float freely * On inspiration, this segment would be sucked inwards instead of lifting upwards * Paradoxical respiration

What is the black arrow?