Diaphragm

Diaphragm Key Points

The diaphragm has 3 main apertures or openings:

• Caval at T8
• Oesophageal T10
• Aortic T12

The following structures perforate the diaphragm through these apertures:



Innervation is from C3, C4 and C5 via the phrenic nerve and the intercostal nerves

Memory aid

There are a number of ways of remembering the openings of the diaphragm. One way to remember the levels is simply the number of letters of the main structure passing through:

• vena cava, 8 letters, opening at T8
• oesophagus, 10 letters, opening at T10
• aortic hiatus, 12 letters, opening at T12

Movement of the diaphragm

Surface markings of the diaphragm

• The xiphisternum is anterior to the central tendon of the diaphragm.
• The postero-inferior margin of the diaphragm is the T12 vertebra. This is not the lowest point of attachment as two appendages called the crura descend onto the lumbar vertebrae
• The anteroinferior margin is the costal margin
• Domes of diaphragm said to correspond to the 5th rib in mid-clavicular line during mid respiration
• Right dome slighter higher than left - upper border 5th rib, Left dome lower border 5th rib. During expiration the right dome may be as high as the 4th intercostal space.

With regards to the attachments of the diaphragm it is worth noting that the diaphragm has several points of attachment.

• Anteriorly it is attached to the xiphisternum.
• Posteriorly it has two tendons called the crura (singular =crus). These blend with the anterior longitudinal ligament of the vertebrae at L1-L3 level.
• Laterally onto the lower 6 ribs (ribs 7-12) and costal cartilages.
• Central tendon fuses with fibrous pericardium above